Ruby Issue Tracking System: Issueshttps://bugs.ruby-lang.org/https://bugs.ruby-lang.org/favicon.ico?17113305112023-06-15T00:44:52ZRuby Issue Tracking System
Redmine Ruby master - Bug #19733 (Feedback): Kernel#Rational does not accept prefix 0https://bugs.ruby-lang.org/issues/197332023-06-15T00:44:52Zsawa (Tsuyoshi Sawada)
<p><code>Integer</code> and <code>Rational</code> literals accept prefix <code>0</code>. There is no difference in this respect.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mb">0b10</span> <span class="c1"># => 2</span>
<span class="mb">0b10</span><span class="n">r</span> <span class="c1"># => (2/1)</span>
</code></pre>
<p>However, when it comes to <code>Kernel#Integer</code> and <code>Kernel#Rational</code>, the former accepts prefix <code>0</code> while the latter does not. This is confusing. And as I do not see any reason they should behave differently, I think it is a bug.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Integer</span><span class="p">(</span><span class="s2">"0b10"</span><span class="p">)</span> <span class="c1"># => 2</span>
<span class="no">Rational</span><span class="p">(</span><span class="s2">"0b10"</span><span class="p">)</span> <span class="c1"># !> ArgumentError</span>
</code></pre> Ruby master - Bug #18765 (Closed): Wrong description introduced by https://github.com/ruby/ruby/p...https://bugs.ruby-lang.org/issues/187652022-05-09T07:44:14Zsawa (Tsuyoshi Sawada)
<p>Commit <a href="https://github.com/ruby/ruby/pull/4938/files" class="external">https://github.com/ruby/ruby/pull/4938/files</a> introduced problems and made the description wrong.</p>
<ol>
<li>
<p>For methods <code>slice_after</code> and <code>slice_when</code>, it introduces expressions like "partition elements into arrays ('slices')", and for method <code>chunk_while</code>, "partition elements into arrays ('chunks')". It suggests to call the resulting elements using different words depending on the name of the method. But that does not make sense. They are all simply arrays, and there is no need to distinguish a "slice array" from a "chunk array". (They can all be called an "array", "slice", or "chunk", or whatever.)</p>
<p>Perhaps, it is attempting to explain where the method names came from, under the assumption that the words "slice" and "chunk" in these method names are nouns. If so, that is wrong. The succeeding parts "when (block)" and "while (block)" are (to correspond to English) adverbial clauses, not adjectival (relative) clauses; hence, these "slice" and "chunk" must be interpreted as verbs, not nouns. In fact, "a slice when y is not a successor of x" or "a chunk while y is a successor of x" does not make sense, whereas "slice it when y is not a successor of x" and "chunk them while y is a successor of x" do make sense.</p>
<p>The difference between the "slice" and "chunk" methods lies in the process, not the return value. If you want to use these words, it can be something like "slice the receiver into arrays when the block returns a truthy value" and "chunk the elements together while the block returns a truthy value".</p>
</li>
<li>
<p>In the description of <code>slice_when</code> and <code>chunk_while</code>, it says "it calls the block with each element and its successor", but that is not true. If you are going to phrase it that way, then it only calls each element except for the last one.</p>
</li>
<li>
<p>In the description of <code>slice_when</code>, it says "begins a new slice if and only if the block returns a truthy value", but that is not true. Regardless of the value of the block, the first element always begins a new "slice".</p>
</li>
<li>
<p>Most crucially, in the description of <code>chunk_while</code>, the expression "begins a new chunk if and only if the block returns a truthy value" is entirely wrong.</p>
</li>
</ol> Ruby master - Feature #18690 (Open): Allow `Kernel#then` to take argumentshttps://bugs.ruby-lang.org/issues/186902022-04-12T09:20:21Zsawa (Tsuyoshi Sawada)
<p><code>Kernel#then</code> passes the receiver to the block as its first positional block parameter.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mf">1.5</span><span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="o">|</span><span class="n">x</span><span class="o">|</span> <span class="no">Math</span><span class="p">.</span><span class="nf">atan</span><span class="p">(</span><span class="n">x</span><span class="p">)}</span>
</code></pre>
<p>I would like to propose to let <code>then</code> take arguments, which would be passed to the block as the other block parameters.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mi">3</span><span class="p">.</span><span class="nf">then</span><span class="p">(</span><span class="mi">4</span><span class="p">){</span><span class="o">|</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="o">|</span> <span class="no">Math</span><span class="p">.</span><span class="nf">hypot</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">)}</span>
</code></pre>
<p>There are two uses. First, to separate bulky or repeated parameters from the routine. Instead of writing:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">honyarara</span><span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="o">|</span><span class="n">x</span><span class="o">|</span>
<span class="n">foo</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">bar</span><span class="p">(</span><span class="n">fugafugafuga</span><span class="p">)</span>
<span class="n">baz</span><span class="p">(</span><span class="n">hogehogehoge</span><span class="p">)</span>
<span class="n">qux</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">fugafugafuga</span><span class="p">,</span> <span class="n">hogehogehoge</span><span class="p">)</span>
<span class="p">}</span>
</code></pre>
<p>we can then write:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">honyarara</span><span class="p">.</span><span class="nf">then</span><span class="p">(</span><span class="n">fugafugafuga</span><span class="p">,</span> <span class="n">hogehogehoge</span><span class="p">){</span><span class="o">|</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">z</span><span class="o">|</span>
<span class="n">foo</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">bar</span><span class="p">(</span><span class="n">y</span><span class="p">)</span>
<span class="n">baz</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">qux</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">z</span><span class="p">)</span>
<span class="p">}</span>
</code></pre>
<p>Second, to use a proc with multiple parameters when, for some reason, you do not want to define a method to do it:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">p</span> <span class="o">=</span> <span class="o">-></span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">z</span><span class="p">){</span>
<span class="n">foo</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">bar</span><span class="p">(</span><span class="n">y</span><span class="p">)</span>
<span class="n">baz</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">qux</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">z</span><span class="p">)</span>
<span class="p">}</span>
<span class="n">honyarara</span><span class="p">.</span><span class="nf">then</span><span class="p">(</span><span class="n">fugafugafuga</span><span class="p">,</span> <span class="n">hogehogehoge</span><span class="p">,</span> <span class="o">&</span><span class="nb">p</span><span class="p">)</span>
</code></pre> Ruby master - Feature #18331 (Open): Kernel.#Timehttps://bugs.ruby-lang.org/issues/183312021-11-13T12:27:30Zsawa (Tsuyoshi Sawada)
<p>I remember that, once, Matz suggested a new literal notation for date/time, but he later withdrew it. It seems like introducing new syntax at this point is less realistic. But I believe that many people have wanted a simple way to create a date/time object.</p>
<p>I propose <code>Kernel.Time</code> or <code>Kernel#Time</code>, in much of the same way as <code>Kernel.#Integer</code>, <code>Kernel.#Float</code>, <code>Kernel.#Complex</code> and others. It should take a string as the first required argument and some optional keyword arguments.</p>
<pre><code class="rb syntaxhl" data-language="rb"><span class="no">Time</span><span class="p">(</span><span class="s2">"2021-11-13T21:21:18.027294 +0900"</span><span class="p">)</span> <span class="c1"># => 2021-11-13 21:21:18.027294 +0900</span>
<span class="no">Time</span><span class="p">(</span><span class="s2">"2021-11-13 21:21:18.027294 +0900"</span><span class="p">)</span> <span class="c1"># => 2021-11-13 21:21:18.027294 +0900</span>
<span class="no">Time</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => nil</span>
</code></pre>
<p>I leave out the specifics. There should be room for debate.</p>
<p>I wish the features nobu implemented in <a href="https://bugs.ruby-lang.org/issues/18033" class="external">https://bugs.ruby-lang.org/issues/18033</a> for <code>Time.new</code> can be carried over to <code>Kernel.#Time</code>.</p> Ruby master - Feature #17773 (Open): Alias `Numeric#zero?` and `Float#zero?` as `Numeric#empty?` ...https://bugs.ruby-lang.org/issues/177732021-04-02T03:49:45Zsawa (Tsuyoshi Sawada)
<p>When dealing with user input fields as in web applications, there are typical values that we want to consider as the default and/or absence of user input. For string/text inputs, list items, and attributes, we have <code>String#empty?</code>, <code>Array#empty?</code>, and <code>Hash#empty?</code> respectively, which seem to correspond to those cases. As for numerics, there are <code>Numeric#zero?</code> and <code>Float#zero?</code>.</p>
<p>However, there is no single term that covers all these cases. In a routine to check through the fields whether there is user input, we have to selectively use <code>empty?</code> or <code>zero?</code> depending on the type of the input field.</p>
<p>Many programming languages other than Ruby typically consider these values as falsy with respect to logical calculation. Ruby handles only <code>nil</code> and <code>false</code> as falsy, and that has clear advantages in many aspects, but with the cost of losing a simple way to handle these default values.</p>
<p>I propose to alias <code>Numeric#zero?</code> as <code>Numeric#empty?</code> and <code>Float#zero?</code> as <code>Float#empty?</code> so that we can simply use <code>empty?</code>. At first, calling zero as empty might sound strange, but at least for non-negative integers, set theoretic definitions usually define zero as the empty set, so it is not that strange after all.</p>
<p>Ruby on Rails' <code>blank?</code> is conceptually similar to this, but <code>0.blank?</code> returns <code>false</code>, so it is a different concept.</p> Ruby master - Feature #17316 (Open): On memoizationhttps://bugs.ruby-lang.org/issues/173162020-11-11T10:22:03Zsawa (Tsuyoshi Sawada)
<p>I have seen so many attempts to memoize a value in the form:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="vi">@foo</span> <span class="o">||=</span> <span class="n">some_heavy_calculation</span><span class="p">(</span><span class="o">...</span><span class="p">)</span>
</code></pre>
<p>improperly, i.e., even when the value can potentially be falsy. This practice is wide spread, and since in most cases memoization is about efficiency and it would not be critical if it does not work correctly, people do not seem to care so much about correcting the wrong usage.</p>
<p>In such case, the correct form would be:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">unless</span> <span class="n">instance_variable_defined?</span><span class="p">(</span><span class="ss">:@foo</span><span class="p">)</span>
<span class="vi">@foo</span> <span class="o">=</span> <span class="n">some_heavy_calculation</span><span class="p">(</span><span class="o">...</span><span class="p">)</span>
<span class="k">end</span>
</code></pre>
<p>but this looks too long, and perhaps that is keeping people away from using it.</p>
<p>What about allowing <code>Kernel#instance_variable_set</code> to take a block instead of the second argument, in which case the assignment should be done only when the instance variable is not defined?</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">instance_variable_set</span><span class="p">(</span><span class="ss">:@foo</span><span class="p">){</span><span class="n">some_heavy_calculation</span><span class="p">(</span><span class="o">...</span><span class="p">)}</span>
</code></pre>
<p>Or, if that does not look right or seems to depart from the original usage of <code>instance_variable_set</code>, then what about having a new method?</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">memoize</span><span class="p">(</span><span class="ss">:foo</span><span class="p">){</span><span class="n">some_heavy_calculation</span><span class="p">(</span><span class="o">...</span><span class="p">)}</span>
</code></pre> Ruby master - Bug #17167 (Closed): Nested numbered parameters are not allowedhttps://bugs.ruby-lang.org/issues/171672020-09-12T15:20:28Zsawa (Tsuyoshi Sawada)
<p>Numbered parameter is allowed in an ordinary block:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">],</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">]].</span><span class="nf">each</span><span class="p">{</span><span class="nb">p</span> <span class="n">_1</span><span class="p">}</span>
<span class="c1"># >> [1, 2]</span>
<span class="c1"># >> [3, 4]</span>
</code></pre>
<p>as well as in a nested block:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">],</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">]].</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">a</span><span class="o">|</span> <span class="n">a</span><span class="p">.</span><span class="nf">each</span><span class="p">{</span><span class="nb">p</span> <span class="n">_1</span><span class="p">}}</span>
<span class="c1"># >> 1</span>
<span class="c1"># >> 2</span>
<span class="c1"># >> 3</span>
<span class="c1"># >> 4</span>
</code></pre>
<p>but not in both at the same time:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">],</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">]].</span><span class="nf">each</span><span class="p">{</span><span class="n">_1</span><span class="p">.</span><span class="nf">each</span><span class="p">{</span><span class="nb">p</span> <span class="n">_1</span><span class="p">}}</span>
<span class="c1"># >> SyntaxError ((irb):2: numbered parameter is already used in) outer block here</span>
<span class="c1"># >> [[1, 2], [3, 4]].each{_1.each{p _1}}</span>
<span class="o">^~</span>
</code></pre>
<p>I feel that this should be a bug.</p>
<p>Note that an error is not raised when an ordinary block parameter with the same name is used in the outer and the inner blocks:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">],</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">]].</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">v</span><span class="o">|</span> <span class="n">v</span><span class="p">.</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">v</span><span class="o">|</span> <span class="nb">p</span> <span class="n">v</span><span class="p">}}</span>
<span class="c1"># >> 1</span>
<span class="c1"># >> 2</span>
<span class="c1"># >> 3</span>
<span class="c1"># >> 4</span>
</code></pre>
<p>If this is not a bug, the specification of numbered parameters is too complex. How am I supposed to use numbered parameters in such use case as above?</p> Ruby master - Feature #17165 (Open): Add `filter` and `flatten` keywords to `Enumerable#map`https://bugs.ruby-lang.org/issues/171652020-09-12T14:46:54Zsawa (Tsuyoshi Sawada)
<p>I had a use case to do <code>map</code> on an enumerable, with 1-level flattening, while skipping <code>nil</code> values.</p>
<p>There are convenient <code>Enumerable#flat_map</code> and <code>Enumerable#filter_map</code> methods, but the problem is that they cannot be used at the same time. I had to chose to do either of the following:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">array</span>
<span class="p">.</span><span class="nf">filter_map</span> <span class="k">do</span> <span class="o">|</span><span class="n">foo</span><span class="o">|</span>
<span class="n">bar</span> <span class="o">=</span> <span class="n">baz</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="k">next</span> <span class="k">unless</span> <span class="n">bar</span>
<span class="n">bar</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">...</span><span class="p">}</span>
<span class="k">end</span>
<span class="p">.</span><span class="nf">flatten</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
</code></pre>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">array</span>
<span class="p">.</span><span class="nf">flat_map</span> <span class="k">do</span> <span class="o">|</span><span class="n">foo</span><span class="o">|</span>
<span class="n">bar</span> <span class="o">=</span> <span class="n">baz</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="k">next</span> <span class="k">unless</span> <span class="n">bar</span>
<span class="n">bar</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">...</span><span class="p">}</span>
<span class="k">end</span>
<span class="p">.</span><span class="nf">compact</span>
</code></pre>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">array</span>
<span class="p">.</span><span class="nf">flat_map</span> <span class="k">do</span> <span class="o">|</span><span class="n">foo</span><span class="o">|</span>
<span class="n">bar</span> <span class="o">=</span> <span class="n">baz</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="k">next</span> <span class="p">[]</span> <span class="k">unless</span> <span class="n">bar</span>
<span class="n">bar</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">...</span><span class="p">}</span>
<span class="k">end</span>
</code></pre>
<p>The last one of the above may not look so bad, but it requires an extra consideration, and is a bit hacky. When you are in a hurry, it just might not come to your mind.</p>
<p>This led me to realize that <code>flat_map</code> and <code>filter_map</code> should not be independent operations, but are rather some different modes of the operation <code>map</code>. There is no reason for the modes to be mutually exclusive of one another, and a use case that I mentioned above may arise.</p>
<p>I propose to add <code>filter</code> and <code>flatten</code> as optional keyword arguments to <code>Enumerable#map</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">array</span>
<span class="p">.</span><span class="nf">map</span><span class="p">(</span><span class="ss">filter: </span><span class="kp">true</span><span class="p">,</span> <span class="ss">flatten: </span><span class="mi">1</span><span class="p">)</span> <span class="k">do</span> <span class="o">|</span><span class="n">foo</span><span class="o">|</span>
<span class="n">bar</span> <span class="o">=</span> <span class="n">baz</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="k">next</span> <span class="k">unless</span> <span class="n">bar</span>
<span class="n">bar</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">...</span><span class="p">}</span>
<span class="k">end</span>
</code></pre>
<p>In fact, even when the two parameters are not used together, I believe it would be easier to the brain and I would feel much more comfortable to pass <code>filter: true</code> or <code>flatten: 1</code> to <code>map</code> when necessary rather than having to deicide whether to use <code>map</code> or <code>flat_map</code> or use <code>map</code> or <code>filter_map</code>.</p>
<p>Furthermore, this would make it possible to do flattening of an arbitrary depth (as specified by the parameter) during map.</p> Ruby master - Feature #17163 (Open): Rename `begin`https://bugs.ruby-lang.org/issues/171632020-09-09T03:04:22Zsawa (Tsuyoshi Sawada)
<p><code>Range#begin</code> is a getter method; it returns a value, and does not have a side effect, or does any calculation. Nevertheless, "begin" is a verb, so there is a mismatch. I would rather expect a noun.</p>
<p>It has a counterpart <code>Range#end</code>, and "end" is a noun as well as a verb, so that is not strange.</p>
<p>I propose to alias <code>Range#begin</code> to a noun or a nominal. "beginning" will work, but it may be too long, so what about "start", which works as a noun (as well as a verb)?</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Range</span><span class="c1">#start</span>
</code></pre> Ruby master - Feature #17097 (Open): `map_min`, `map_max`https://bugs.ruby-lang.org/issues/170972020-07-31T12:33:39Zsawa (Tsuyoshi Sawada)
<p><code>min</code>, <code>min_by</code>, <code>max</code>, <code>max_by</code> return the element that leads to the minimum or the maximum value, but I think it is as, or even more, frequent that we are interested in the minimum or the maximum value itself rather than the element. For example, to get the length of the longest string in an array, we do:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="sx">%w[aa b cccc dd]</span><span class="p">.</span><span class="nf">max_by</span><span class="p">(</span><span class="o">&</span><span class="ss">:length</span><span class="p">).</span><span class="nf">length</span> <span class="c1"># => 4</span>
<span class="sx">%w[aa b cccc dd]</span><span class="p">.</span><span class="nf">map</span><span class="p">(</span><span class="o">&</span><span class="ss">:length</span><span class="p">).</span><span class="nf">max</span> <span class="c1"># => 4</span>
</code></pre>
<p>I propose to have methods that return the minimum or the maximum value. Temporarily calling them <code>map_min</code>, <code>map_max</code>, they should work like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="sx">%w[aa b cccc dd]</span><span class="p">.</span><span class="nf">map_max</span><span class="p">(</span><span class="o">&</span><span class="ss">:length</span><span class="p">)</span> <span class="c1"># => 4</span>
</code></pre>
<p><code>map_min</code>, <code>map_max</code> are implementation-centered names, so perhaps better names should replace them, just like <code>yield_self</code> was replaced by <code>then</code>.</p> Ruby master - Feature #17006 (Open): Let `Kernel#Hash` take a block to provide the default valuehttps://bugs.ruby-lang.org/issues/170062020-07-03T08:09:01Zsawa (Tsuyoshi Sawada)
<p>Sometimes, we need to create a hash that has explicit key-value pairs as well as a default value, but there has not been a way to do that at once. The most naive way is to do like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">h</span> <span class="o">=</span> <span class="p">{</span><span class="ss">a: </span><span class="mi">1</span><span class="p">,</span> <span class="ss">b: </span><span class="mi">2</span><span class="p">}</span>
<span class="n">h</span><span class="p">.</span><span class="nf">default_proc</span> <span class="o">=</span> <span class="o">-></span><span class="p">(</span><span class="n">h</span><span class="p">,</span> <span class="n">k</span><span class="p">){</span><span class="k">raise</span> <span class="s2">"Unknown key </span><span class="si">#{</span><span class="n">k</span><span class="si">}</span><span class="s2">"</span><span class="p">}</span>
<span class="n">h</span> <span class="c1"># => ...</span>
</code></pre>
<p>A more sophisticated way is this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Hash</span><span class="p">.</span><span class="nf">new</span><span class="p">{</span><span class="o">|</span><span class="n">h</span><span class="p">,</span> <span class="n">k</span><span class="o">|</span> <span class="k">raise</span> <span class="s2">"Unknown key </span><span class="si">#{</span><span class="n">k</span><span class="si">}</span><span class="s2">"</span><span class="p">}.</span><span class="nf">merge</span><span class="p">({</span><span class="ss">a: </span><span class="mi">1</span><span class="p">,</span> <span class="ss">b: </span><span class="mi">2</span><span class="p">})</span>
</code></pre>
<p>But that is still not short enough, and it also looks backwards, i.e., we usually want to specify the explicit key-value pairs before the default value.</p>
<p>My proposal is to allow <code>Kernel#Hash</code> to take a block that provides the default value in the same way as the block of <code>Hash.new</code>:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Hash</span><span class="p">({</span><span class="ss">a: </span><span class="mi">1</span><span class="p">,</span> <span class="ss">b: </span><span class="mi">2</span><span class="p">}){</span><span class="o">|</span><span class="n">h</span><span class="p">,</span> <span class="n">k</span><span class="o">|</span> <span class="k">raise</span> <span class="s2">"Unknown key </span><span class="si">#{</span><span class="n">k</span><span class="si">}</span><span class="s2">"</span><span class="p">}</span>
</code></pre> Ruby master - Bug #16842 (Closed): `inspect` prints the UTF-8 character U+0085 (NEXT LINE) verbat...https://bugs.ruby-lang.org/issues/168422020-05-09T14:35:11Zsawa (Tsuyoshi Sawada)
<p>The UTF-8 character U+0085 (NEXT LINE) is not printable, but <code>inspect</code> prints the character verbatim (within double quotation):</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mh">0x85</span><span class="p">.</span><span class="nf">chr</span><span class="p">(</span><span class="no">Encoding</span><span class="o">::</span><span class="no">UTF_8</span><span class="p">).</span><span class="nf">match?</span><span class="p">(</span><span class="sr">/\p{print}/</span><span class="p">)</span> <span class="c1"># => false</span>
<span class="mh">0x85</span><span class="p">.</span><span class="nf">chr</span><span class="p">(</span><span class="no">Encoding</span><span class="o">::</span><span class="no">UTF_8</span><span class="p">).</span><span class="nf">inspect</span>
<span class="c1">#=> "\"</span>
<span class="p">\</span><span class="s2">""</span>
</code></pre>
<p>My understanding is that non-printable characters are not printed verbatim with <code>inspect</code>:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"</span><span class="se">\n</span><span class="s2">"</span><span class="p">.</span><span class="nf">match?</span><span class="p">(</span><span class="sr">/\p{print}/</span><span class="p">)</span> <span class="c1"># => false</span>
<span class="s2">"</span><span class="se">\n</span><span class="s2">"</span><span class="p">.</span><span class="nf">inspect</span> <span class="c1">#=> "\"\\n\""</span>
</code></pre>
<p>while printable characters are:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"a"</span><span class="p">.</span><span class="nf">match?</span><span class="p">(</span><span class="sr">/\p{print}/</span><span class="p">)</span> <span class="c1"># => true</span>
<span class="s2">"a"</span><span class="p">.</span><span class="nf">inspect</span> <span class="c1"># => "\"a\""</span>
</code></pre>
<p>I ran the following script, and found that U+0085 is the only character within the range U+0000 to U+FFFF that behaves like this.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">def</span> <span class="nf">verbatim?</span><span class="p">(</span><span class="n">char</span><span class="p">)</span>
<span class="o">!</span><span class="n">char</span><span class="p">.</span><span class="nf">inspect</span><span class="p">.</span><span class="nf">start_with?</span><span class="p">(</span><span class="sr">%r{</span><span class="se">\"\\</span><span class="sr">[a-z]}</span><span class="p">)</span>
<span class="k">end</span>
<span class="k">def</span> <span class="nf">printable?</span><span class="p">(</span><span class="n">char</span><span class="p">)</span>
<span class="n">char</span><span class="p">.</span><span class="nf">match?</span><span class="p">(</span><span class="sr">/\p{print}/</span><span class="p">)</span>
<span class="k">end</span>
<span class="p">(</span><span class="mh">0x0000</span><span class="o">..</span><span class="mh">0xffff</span><span class="p">).</span><span class="nf">each</span> <span class="k">do</span> <span class="o">|</span><span class="n">i</span><span class="o">|</span>
<span class="k">begin</span>
<span class="n">char</span> <span class="o">=</span> <span class="n">i</span><span class="p">.</span><span class="nf">chr</span><span class="p">(</span><span class="no">Encoding</span><span class="o">::</span><span class="no">UTF_8</span><span class="p">)</span>
<span class="k">rescue</span> <span class="no">RangeError</span>
<span class="k">next</span>
<span class="k">end</span>
<span class="nb">puts</span> <span class="s1">'%#x'</span> <span class="o">%</span> <span class="n">i</span> <span class="k">unless</span> <span class="n">verbatim?</span><span class="p">(</span><span class="n">char</span><span class="p">)</span> <span class="o">==</span> <span class="n">printable?</span><span class="p">(</span><span class="n">char</span><span class="p">)</span>
<span class="k">end</span>
</code></pre> Ruby master - Feature #16818 (Open): Rename `Range#%` to `Range#/`https://bugs.ruby-lang.org/issues/168182020-04-26T02:15:08Zsawa (Tsuyoshi Sawada)
<p><code>Range#%</code> was introduced as an alias of <code>Range#step</code> by 14697, but it is counter-intuitive and confusing.</p>
<p>Iteration in the following:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">((</span><span class="mi">5</span><span class="o">..</span><span class="mi">14</span><span class="p">)</span> <span class="o">%</span> <span class="mi">3</span><span class="p">).</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">i</span><span class="o">|</span> <span class="nb">p</span> <span class="n">i</span><span class="p">}</span>
<span class="c1">#>> 5</span>
<span class="c1">#>> 8</span>
<span class="c1">#>> 11</span>
<span class="c1">#>> 14</span>
</code></pre>
<p>is not based on <code>x % y</code> in any sense. In fact, actually applying <code>% 3</code> to the selected elements returns a unique value <code>2</code>, and it is not obvious how this is related to the iteration.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[</span><span class="mi">5</span><span class="p">,</span> <span class="mi">8</span><span class="p">,</span> <span class="mi">11</span><span class="p">,</span> <span class="mi">14</span><span class="p">].</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="n">i</span><span class="o">|</span> <span class="n">i</span> <span class="o">%</span> <span class="mi">3</span><span class="p">}</span>
<span class="c1"># => [2, 2, 2, 2]</span>
</code></pre>
<p>Rather, the concept seems to be based on <code>/</code>. Applying <code>/ 3</code> to the relevant elements returns a sequence <code>1, 2, 3, 4</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[</span><span class="mi">5</span><span class="p">,</span> <span class="mi">8</span><span class="p">,</span> <span class="mi">11</span><span class="p">,</span> <span class="mi">14</span><span class="p">].</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="n">i</span><span class="o">|</span> <span class="n">i</span> <span class="o">/</span> <span class="mi">3</span><span class="p">}</span>
<span class="c1"># => [1, 2, 3, 4]</span>
</code></pre>
<p>Hence, <code>(5..14).step(3)</code> can be interpreted like this: Iterate over the <a href="https://en.wikipedia.org/wiki/Equivalence_class" class="external">equivalence class</a> (quotient set) of range <code>5..14</code> yielded by <code>/ 3</code>.</p>
<p>Notice that the number of elements in <code>[5, 8, 11, 14]</code> is 4, which is <code>(14 - 5 + 1) / 3.0).ceil</code>, but is not related to <code>%</code>.</p>
<p>So I propose that the alias of <code>Range#step</code> should be <code>Range#/</code>, and <code>Range#%</code> should be deprecated as soon as possible before its use accumulates:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">((</span><span class="mi">5</span><span class="o">..</span><span class="mi">14</span><span class="p">)</span> <span class="o">/</span> <span class="mi">3</span><span class="p">).</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">i</span><span class="o">|</span> <span class="nb">p</span> <span class="n">i</span><span class="p">}</span>
<span class="c1">#>> 5</span>
<span class="c1">#>> 8</span>
<span class="c1">#>> 11</span>
<span class="c1">#>> 14</span>
</code></pre>
<hr>
<p>P.S.</p>
<p>And if <code>Range#%</code> were to be introduced at all, I would rather expect it to behave like the following:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">((</span><span class="mi">5</span><span class="o">..</span><span class="mi">14</span><span class="p">)</span> <span class="o">%</span> <span class="mi">3</span><span class="p">).</span><span class="nf">each</span><span class="p">{</span><span class="o">|</span><span class="n">i</span><span class="o">|</span> <span class="nb">p</span> <span class="n">i</span><span class="p">}</span>
<span class="c1">#>> 5</span>
<span class="c1">#>> 6</span>
<span class="c1">#>> 7</span>
</code></pre>
<p>which is why I claimed above that the current <code>Range#%</code> is confusing.</p> Ruby master - Feature #16703 (Open): Namespace parameter for `Module#name`https://bugs.ruby-lang.org/issues/167032020-03-23T10:57:03Zsawa (Tsuyoshi Sawada)
<p>I often see code that intends to remove a portion of the namespace from a module/class name like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">class</span> <span class="nc">B</span> <span class="k">class</span> <span class="nc">C</span><span class="p">;</span> <span class="k">end</span> <span class="k">end</span> <span class="k">end</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">.</span><span class="nf">delete_prefix</span><span class="p">(</span><span class="s2">"A::"</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">.</span><span class="nf">delete_prefix</span><span class="p">(</span><span class="s2">"A::B::"</span><span class="p">)</span> <span class="c1"># => "C"</span>
</code></pre>
<p>I think a large portion of the use cases of the method <code>String#delete_prefix</code> belongs to such use cases.</p>
<p>I propose to let <code>Module#name</code> take an optional parameter that expresses the name space. The parameter should be either a module, string, or a symbol.</p>
<p>I am not sure whether a positional argument or a keyword argument is better.</p>
<p>Positional argument:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="s2">"A"</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">:A</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="no">A</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="s2">"A::B"</span><span class="p">)</span> <span class="c1"># => "C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">:"A::B"</span><span class="p">)</span> <span class="c1"># => "C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="p">)</span> <span class="c1"># => "C"</span>
</code></pre>
<p>Keyword argument:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: </span><span class="s2">"A"</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: :A</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: </span><span class="no">A</span><span class="p">)</span> <span class="c1"># => "B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: </span><span class="s2">"A::B"</span><span class="p">)</span> <span class="c1"># => "C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: :"A::B"</span><span class="p">)</span> <span class="c1"># => "C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="ss">namespace: </span><span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="p">)</span> <span class="c1"># => "C"</span>
</code></pre>
<p>If the module/class does not belong to the namespace given as the parameter, then perhaps it would be a good idea to prepend the name with <code>::</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">class</span> <span class="nc">B</span><span class="p">;</span> <span class="k">class</span> <span class="nc">D</span> <span class="k">end</span> <span class="k">end</span> <span class="k">end</span>
<span class="k">class</span> <span class="nc">E</span> <span class="k">end</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span> <span class="c1"># => "A::B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">D</span><span class="p">)</span> <span class="c1"># => "::A::B::C"</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">name</span><span class="p">(</span><span class="no">E</span><span class="p">)</span> <span class="c1"># => "::A::B::C"</span>
</code></pre> Ruby master - Bug #16685 (Closed): IRB auto indent does not work for single-line method definitionshttps://bugs.ruby-lang.org/issues/166852020-03-10T21:41:44Zsawa (Tsuyoshi Sawada)
<p>IRB auto indent does not work correctly for single line method definitions within a class. It ends up like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">001</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">class</span> <span class="nc">Foo</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">002</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">def</span> <span class="nf">a</span><span class="p">;</span> <span class="k">end</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">003</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">def</span> <span class="nf">b</span><span class="p">;</span> <span class="k">end</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">004</span><span class="p">:</span><span class="mi">0</span><span class="o">></span> <span class="k">end</span>
<span class="o">=></span> <span class="ss">:b</span>
</code></pre>
<p>I believe it should end up like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">001</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">class</span> <span class="nc">Foo</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">002</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">def</span> <span class="nf">a</span><span class="p">;</span> <span class="k">end</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">003</span><span class="p">:</span><span class="mi">1</span><span class="o">*</span> <span class="k">def</span> <span class="nf">b</span><span class="p">;</span> <span class="k">end</span>
<span class="n">irb</span><span class="p">(</span><span class="n">main</span><span class="p">):</span><span class="mo">004</span><span class="p">:</span><span class="mi">0</span><span class="o">></span> <span class="k">end</span>
<span class="o">=></span> <span class="ss">:b</span>
</code></pre> Ruby master - Feature #16684 (Open): Use the word "to" instead of "from" in backtracehttps://bugs.ruby-lang.org/issues/166842020-03-10T16:00:53Zsawa (Tsuyoshi Sawada)
<p>The most-recent-call-last order of backtrace introduced by <a class="issue tracker-2 status-5 priority-4 priority-default closed" title="Feature: Add option to print backtrace in reverse order (stack frames first and error last) (Closed)" href="https://bugs.ruby-lang.org/issues/8661">#8661</a>:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">def</span> <span class="nf">a</span><span class="p">;</span> <span class="k">raise</span> <span class="k">end</span>
<span class="k">def</span> <span class="nf">b</span><span class="p">;</span> <span class="n">a</span> <span class="k">end</span>
<span class="k">def</span> <span class="nf">c</span><span class="p">;</span> <span class="n">b</span> <span class="k">end</span>
<span class="n">c</span>
</code></pre>
<p><strong>Current</strong></p>
<pre><code>Traceback (most recent call last):
3: from foo.rb:4:in `<main>'
2: from foo.rb:3:in `c'
1: from foo.rb:2:in `b'
foo.rb:1:in `a': unhandled exception
</code></pre>
<p>is intuitive to me, and I hope it is retained. However, there are people complaining that it is confusing. I believe the unnaturalness is (at least partly) due to the fact that the word "from" is used, which made sense when backtrace was displayed in most-recent-call-first order,</p>
<pre><code>foo.rb:1:in `a': unhandled exception
1: from foo.rb:2:in `b'
2: from foo.rb:3:in `c'
3: from foo.rb:4:in `<main>'
</code></pre>
<p>but not any more. Here, my understanding is that "from" means that the previous line was called <strong>from</strong> that line.</p>
<p>I propose that, so long as the most-recent-call-last order is adopted, the word "to" should be used rather than "from", which would mean that the previous line leads <strong>to</strong> that line:</p>
<p><strong>Proposed 1</strong></p>
<pre><code>Traceback (most recent call last):
3: to foo.rb:4:in `<main>'
2: to foo.rb:3:in `c'
1: to foo.rb:2:in `b'
foo.rb:1:in `a': unhandled exception
</code></pre>
<p>Or, as an alternative, if it looks unnatural to have "to" in the first line, and to lack one before the message line, we may put it at the end of a line:</p>
<p><strong>Proposed 2</strong></p>
<pre><code>Traceback (most recent call last)
3: foo.rb:4:in `<main>' to:
2: foo.rb:3:in `c' to:
1: foo.rb:2:in `b' to:
foo.rb:1:in `a': unhandled exception
</code></pre>
<p>By using different words, it would become easier to understand the display order at a glance, and even by just looking at a single line.</p> Ruby master - Feature #16601 (Open): Let `nil.to_a` and `nil.to_h` return a fixed instancehttps://bugs.ruby-lang.org/issues/166012020-01-31T10:11:44Zsawa (Tsuyoshi Sawada)
<p>Now, <code>nil.to_s</code> returns a fixed instance:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="kp">nil</span><span class="p">.</span><span class="nf">to_s</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 440</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_s</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 440</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_s</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 440</span>
<span class="o">...</span>
</code></pre>
<p>This is useful when we have some variable <code>foo</code> which may be either <code>nil</code> or a string, and we want to check its emptiness in a condition:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">if</span> <span class="n">foo</span><span class="p">.</span><span class="nf">to_s</span><span class="p">.</span><span class="nf">empty?</span><span class="p">;</span> <span class="o">...</span> <span class="k">end</span>
</code></pre>
<p>By this feature, we do not (need to) create a new instance of an empty string each time we check <code>foo</code>, even when it happens to be <code>nil</code>.</p>
<p>There are similar situations with arrays and hashes. We may have variable <code>bar</code> which may be either <code>nil</code> or an array, or <code>baz</code> which may be either <code>nil</code> or a hash, and we want to check their emptiness in conditions as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">if</span> <span class="n">bar</span><span class="p">.</span><span class="nf">to_a</span><span class="p">.</span><span class="nf">empty?</span><span class="p">;</span> <span class="o">...</span> <span class="k">end</span>
</code></pre>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">if</span> <span class="n">baz</span><span class="p">.</span><span class="nf">to_h</span><span class="p">.</span><span class="nf">empty?</span><span class="p">;</span> <span class="o">...</span> <span class="k">end</span>
</code></pre>
<p>But unlike <code>nil.to_s</code>, the methods <code>nil.to_a</code> and <code>nil.to_h</code> create new instances of empty array or hash each time they are called:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="kp">nil</span><span class="p">.</span><span class="nf">to_a</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 540</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_a</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 560</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_a</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 580</span>
<span class="o">...</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_h</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 460</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_h</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 480</span>
<span class="kp">nil</span><span class="p">.</span><span class="nf">to_h</span><span class="p">.</span><span class="nf">object_id</span> <span class="c1"># => 500</span>
<span class="o">...</span>
</code></pre>
<p>The fact that this is somewhat inefficient discourages the use of <code>foo.to_a</code> or <code>foo.to_h</code> in such use cases.</p>
<p>I request <code>nil.to_a</code> to <code>nil.to_h</code> to return a fixed empty instance.</p> Ruby master - Bug #16599 (Closed): did_you_mean is not activated for NameError and KeyErrorhttps://bugs.ruby-lang.org/issues/165992020-01-28T20:26:23Zsawa (Tsuyoshi Sawada)
<p><a href="https://www.rubydoc.info/gems/did_you_mean/" class="external">This document</a> claims that the did_you_mean gem responds to NameError, NoMethodError, and KeyError, but it actually seems to only respond to NoMethodError.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">foo</span><span class="p">()</span>
<span class="c1"># >> NoMethodError: undefined method `foo' for main:Object</span>
<span class="c1"># >> Did you mean? for</span>
<span class="n">foo</span>
<span class="c1"># >> NameError: undefined local variable or method `foo' for main:Object</span>
<span class="no">Foo</span>
<span class="c1"># >> NameError: uninitialized constant Foo</span>
<span class="p">{</span><span class="ss">foo: </span><span class="mi">1</span><span class="p">}.</span><span class="nf">fetch</span><span class="p">(</span><span class="ss">:bar</span><span class="p">)</span>
<span class="c1"># >> KeyError: key not found: :bar</span>
</code></pre> Ruby master - Bug #16506 (Closed): Documentation for `Module#const_souce_location` is wronghttps://bugs.ruby-lang.org/issues/165062020-01-12T18:17:28Zsawa (Tsuyoshi Sawada)
<p><a href="https://ruby-doc.org/core-2.7.0/Module.html#method-i-const_source_location" class="external">https://ruby-doc.org/core-2.7.0/Module.html#method-i-const_source_location</a> says:</p>
<blockquote>
<p>Returns the Ruby source filename and line number containing <strong>first</strong> definition of constant specified.</p>
</blockquote>
<p>It should be:</p>
<blockquote>
<p>Returns the Ruby source filename and line number containing the <strong>last</strong> definition (the effective definition) of the constant specified.</p>
</blockquote>
<p>It also has an example line:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">p</span> <span class="no">Object</span><span class="p">.</span><span class="nf">const_source_location</span><span class="p">(</span><span class="s1">'A'</span><span class="p">)</span> <span class="c1"># => ["test.rb", 1] -- note it is first entry, not "continuation"</span>
</code></pre>
<p>but that may give the impression that the first-ness is due to the nature of this method. The reason <code>["test.rb", 1]</code> is returned instead of <code>["test.rb", 14]</code> is because the constant is created at line 1, and is only reopened/modified in line 14. Perhaps, this line can be changed to:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">p</span> <span class="no">Object</span><span class="p">.</span><span class="nf">const_source_location</span><span class="p">(</span><span class="s1">'A'</span><span class="p">)</span> <span class="c1"># => ["test.rb", 1] -- note 'A' is created in line 1, and is only reopened/modified in "continuation"</span>
</code></pre>
<p>Adding something like this may make it clear that it is the last definition that is returned:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">D</span> <span class="o">=</span> <span class="s1">'D1'</span>
<span class="no">D</span> <span class="o">=</span> <span class="s1">'D2'</span>
<span class="no">D</span> <span class="o">=</span> <span class="s1">'D3'</span>
<span class="o">...</span>
<span class="no">Object</span><span class="p">.</span><span class="nf">const_source_location</span><span class="p">(</span><span class="s1">'D'</span><span class="p">)</span> <span class="c1"># => returns the location that corresponds to 'D3'</span>
</code></pre> Ruby master - Feature #16246 (Open): require with an optional block that is evaluated when requir...https://bugs.ruby-lang.org/issues/162462019-10-09T05:54:23Zsawa (Tsuyoshi Sawada)
<p>I have some code like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">begin</span>
<span class="nb">require</span> <span class="s2">"foo"</span>
<span class="k">rescue</span> <span class="no">LoadError</span>
<span class="nb">puts</span> <span class="s2">"You need to install foo in order to have the function A work."</span>
<span class="o">...</span>
<span class="k">end</span>
</code></pre>
<p>I request to allow <code>require</code> to take a block which is executed when requiring fails. When <code>require</code> takes a block, a <code>LoadError</code> would not be raised. The code above would then be written like:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">require</span> <span class="s2">"foo"</span> <span class="k">do</span>
<span class="nb">puts</span> <span class="s2">"You need to install foo in order to have the function A work."</span>
<span class="o">...</span>
<span class="k">end</span>
</code></pre>
<p>If there is no need to particularly do anything, then it can be like</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">require</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">){}</span>
</code></pre>
<p>which will cover the use case in <a href="https://bugs.ruby-lang.org/issues/14565" class="external">https://bugs.ruby-lang.org/issues/14565</a>.</p> Ruby master - Feature #16102 (Open): `Symbol#call`https://bugs.ruby-lang.org/issues/161022019-08-14T06:59:46Zsawa (Tsuyoshi Sawada)
<p>Since symbols have a <code>to_proc</code> method, it is natural to expect that they would appear in a method chain like:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="ss">:some_symbol</span><span class="p">.</span><span class="nf">to_proc</span><span class="p">.</span><span class="nf">call</span><span class="p">(</span><span class="o">...</span><span class="p">)</span>
</code></pre>
<p>In fact, I have use cases like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">arrays</span> <span class="o">=</span> <span class="p">[[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">],</span> <span class="p">[</span><span class="s2">"c"</span><span class="p">],</span> <span class="p">[</span><span class="s2">"d"</span><span class="p">,</span> <span class="s2">"e"</span><span class="p">]]</span>
<span class="n">hashes</span> <span class="o">=</span> <span class="p">[{</span><span class="s2">"a"</span> <span class="o">=></span> <span class="mi">1</span><span class="p">},</span> <span class="p">{</span><span class="s2">"b"</span> <span class="o">=></span> <span class="mi">2</span><span class="p">,</span> <span class="s2">"c"</span> <span class="o">=></span> <span class="mi">3</span><span class="p">},</span> <span class="p">{</span><span class="s2">"d"</span> <span class="o">=></span> <span class="mi">4</span><span class="p">,</span> <span class="s2">"e"</span> <span class="o">=></span> <span class="mi">5</span><span class="p">}]</span>
<span class="ss">:product</span><span class="p">.</span><span class="nf">to_proc</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]</span>
<span class="ss">:zip</span><span class="p">.</span><span class="nf">to_proc</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => [["a", "c", "d"], ["b", nil, "e"]]</span>
<span class="ss">:union</span><span class="p">.</span><span class="nf">to_proc</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => ["a", "b", "c", "d", "e"]</span>
<span class="ss">:merge</span><span class="p">.</span><span class="nf">to_proc</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">hashes</span><span class="p">)</span> <span class="c1"># => {"a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5}</span>
</code></pre>
<p>I request <code>Symbol#call</code> to be defined, which would implicitly call <code>to_proc</code> on the receiver and then the conventional <code>Proc#call</code> on the result. Then, I can do:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="ss">:product</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]</span>
<span class="ss">:zip</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => [["a", "c", "d"], ["b", nil, "e"]]</span>
<span class="ss">:union</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">arrays</span><span class="p">)</span> <span class="c1"># => ["a", "b", "c", "d", "e"]</span>
<span class="ss">:merge</span><span class="o">.</span><span class="p">(</span><span class="o">*</span><span class="n">hashes</span><span class="p">)</span> <span class="c1"># => {"a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5}</span>
</code></pre>
<p>This would solve what proposals <a class="issue tracker-2 status-6 priority-4 priority-default closed" title="Feature: Array::zip (Rejected)" href="https://bugs.ruby-lang.org/issues/6499">#6499</a>, <a class="issue tracker-2 status-7 priority-4 priority-default closed" title="Feature: Add Array#rest (with implementation) (Feedback)" href="https://bugs.ruby-lang.org/issues/6727">#6727</a>, <a class="issue tracker-2 status-1 priority-4 priority-default" title="Feature: Array#product_set (Open)" href="https://bugs.ruby-lang.org/issues/7444">#7444</a>, <a class="issue tracker-2 status-1 priority-4 priority-default" title="Feature: Array.zip and Array.product (Open)" href="https://bugs.ruby-lang.org/issues/8970">#8970</a>, <a class="issue tracker-2 status-1 priority-4 priority-default" title="Feature: Make more objects behave like "Functions" (Open)" href="https://bugs.ruby-lang.org/issues/11262">#11262</a> aim to do.</p>
<p>Notice that proposals <a class="issue tracker-2 status-1 priority-4 priority-default" title="Feature: Add Symbol#call to allow to_proc shorthand with arguments (Open)" href="https://bugs.ruby-lang.org/issues/12115">#12115</a> and <a class="issue tracker-2 status-5 priority-4 priority-default closed" title="Feature: Symbol#call, returning method bound with arguments (Closed)" href="https://bugs.ruby-lang.org/issues/15301">#15301</a> ask for <code>Symbol#call</code>, but they ask for different things (a method that returns a proc), and are irrelevant to the current proposal.</p> Ruby master - Bug #16050 (Rejected): :@ is not parsed correctlyhttps://bugs.ruby-lang.org/issues/160502019-08-07T10:56:02Zsawa (Tsuyoshi Sawada)
<p>Symbol literal allows <code>@</code> as the first character:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="ss">:@foo</span> <span class="c1"># => :@foo</span>
</code></pre>
<p>Nevertheless, it does not allow <code>@</code> by itself:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">:</span><span class="err">@</span> <span class="c1"># >> SyntaxError: `@' without identifiers is not allowed as an instance variable name</span>
</code></pre>
<p>This resembles <a class="issue tracker-2 status-6 priority-4 priority-default closed" title="Feature: :~@ and :!@ are not parsed correctly (Rejected)" href="https://bugs.ruby-lang.org/issues/10463">#10463</a>, but while <a class="issue tracker-2 status-6 priority-4 priority-default closed" title="Feature: :~@ and :!@ are not parsed correctly (Rejected)" href="https://bugs.ruby-lang.org/issues/10463">#10463</a> is related to placeholder in a method name, the issue here is related to instance variable name, so I think they are different issues.</p> Ruby master - Feature #16037 (Open): Allow multiple single/double-splatted variables in `in` patt...https://bugs.ruby-lang.org/issues/160372019-08-02T11:50:30Zsawa (Tsuyoshi Sawada)
<p>Pattern matching in <code>in</code> argument seems to prohibit multiple occurrences of single/double-splatted variables.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">case</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">];</span> <span class="k">in</span> <span class="o">*</span><span class="n">foo</span><span class="p">,</span> <span class="no">Integer</span><span class="p">,</span> <span class="n">bar</span><span class="p">;</span> <span class="k">end</span> <span class="c1"># >> (Not SyntaxError)</span>
<span class="k">case</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">];</span> <span class="k">in</span> <span class="o">*</span><span class="n">foo</span><span class="p">,</span> <span class="no">Integer</span><span class="p">,</span> <span class="o">*</span><span class="n">bar</span><span class="p">;</span> <span class="k">end</span> <span class="c1"># >> SyntaxError: unexpected *</span>
</code></pre>
<p>However, unlike conventional constant/variable assignment, it makes sense to have multiple occurrences of single/double-splatted variables in a single pattern matching provided that we have a definite rule regarding whether the splats are greedy or not.</p>
<p>I propose the following.</p>
<ol>
<li>Relax the syntax for pattern matching in <code>in</code> argument to allow multiple occurrences of single/double-splatted variables, and set up a rule regarding whether the splats are greedy or not; preferably greedy.</li>
<li>Further, introduce new syntax for non-greedy splats <code>*?foo</code>, <code>**?foo</code>. Currently, they are syntactically invalid, so I don't think they would conflict with existing code.</li>
</ol>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">case</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="s2">"e"</span><span class="p">,</span> <span class="s2">"f"</span><span class="p">];</span> <span class="k">in</span> <span class="o">*</span><span class="n">foo</span><span class="p">,</span> <span class="no">Integer</span><span class="p">,</span> <span class="o">*</span><span class="n">bar</span><span class="p">;</span> <span class="n">foo</span> <span class="k">end</span> <span class="c1"># => ["a", "b", 3, "c", "d"]</span>
<span class="k">case</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="s2">"e"</span><span class="p">,</span> <span class="s2">"f"</span><span class="p">];</span> <span class="k">in</span> <span class="o">*</span><span class="p">?</span><span class="n">foo</span><span class="p">,</span> <span class="no">Integer</span><span class="p">,</span> <span class="o">*</span><span class="n">bar</span><span class="p">;</span> <span class="n">foo</span> <span class="k">end</span> <span class="c1"># => ["a", "b"]</span>
</code></pre> Ruby master - Bug #16010 (Rejected): Sole single-splatted variable with an array object in an ass...https://bugs.ruby-lang.org/issues/160102019-07-18T10:44:31Zsawa (Tsuyoshi Sawada)
<p>When a single splatted variable appears as the sole argument on the left side of assignment with an array on the right side, that variable is assigned the object as is on the right side:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="o">*</span><span class="n">foo</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">];</span> <span class="n">foo</span> <span class="c1"># => ["a"]</span>
</code></pre>
<p>This behavior looks inconsistent to me, and I am suspecting it is a bug from the reasons below.</p>
<hr>
<p>First, all other constructions that involve assignment of objects to variables work in the same way to one another, but in a different way from the above. That is, they add another nesting level of an array:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">instance_exec</span><span class="p">([</span><span class="s2">"a"</span><span class="p">]){</span><span class="o">|*</span><span class="n">foo</span><span class="o">|</span> <span class="n">foo</span><span class="p">}</span> <span class="c1"># => [["a"]]</span>
<span class="o">->*</span><span class="n">foo</span><span class="p">{</span><span class="n">foo</span><span class="p">}.</span><span class="nf">call</span><span class="p">([</span><span class="s2">"a"</span><span class="p">])</span> <span class="c1"># => [["a"]]</span>
<span class="k">def</span> <span class="nf">baz</span><span class="p">(</span><span class="o">*</span><span class="n">foo</span><span class="p">);</span> <span class="n">foo</span> <span class="k">end</span><span class="p">;</span> <span class="n">baz</span><span class="p">([</span><span class="s2">"a"</span><span class="p">])</span> <span class="c1"># => [["a"]]</span>
</code></pre>
<p>Second, if the object on the right side of the assignment construction in question is not an array, then another level of nesting is added:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="o">*</span><span class="n">foo</span> <span class="o">=</span> <span class="s2">"a"</span><span class="p">;</span> <span class="n">foo</span> <span class="c1"># => ["a"]</span>
</code></pre>
<p>The splat on a variable can be understood to collect the objects into an array. However, in the first example above in which the right side object is an array, all of a sudden, the additional nesting level of array becomes absent. It is not obvious why it behaves differently when the object to be collected is already an array.</p>
<p>Third, when there is no remaining object for the splatted variable, the variable is assigned an empty array,</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="o">*</span><span class="n">foo</span><span class="p">,</span> <span class="n">bar</span> <span class="o">=</span> <span class="s2">"baz"</span><span class="p">;</span> <span class="n">foo</span> <span class="c1"># => []</span>
</code></pre>
<p>and when more than one objects remain for the splatted variable, the variable is assigned an array that includes those objects, even if they are arrays:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="o">*</span><span class="n">foo</span><span class="p">,</span> <span class="n">bar</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">],</span> <span class="p">[</span><span class="s2">"b"</span><span class="p">],</span> <span class="s2">"c"</span><span class="p">;</span> <span class="n">foo</span> <span class="c1"># => [["a"], ["b"]]</span>
</code></pre>
<p>But when there is exactly one object that corresponds to the splatted variable, that object is not included in an array, but is given as is.</p>
<hr>
<p>In short, I believe the correct behavior should be as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="o">*</span><span class="n">foo</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"a"</span><span class="p">];</span> <span class="n">foo</span> <span class="c1"># => [["a"]]</span>
</code></pre> Ruby master - Bug #15987 (Closed): Let `exception` option in `Kernel#Complex`, `Kernel#Float`, `K...https://bugs.ruby-lang.org/issues/159872019-07-05T03:12:16Zsawa (Tsuyoshi Sawada)
<p>The <code>exception</code> option in <code>Kernel#Complex</code>, <code>Kernel#Float</code>, <code>Kernel#Integer</code>, and <code>Kernel#Rational</code> distinguishes <code>false</code> vs. other values.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Integer</span><span class="p">(</span><span class="s2">"z"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">false</span><span class="p">)</span> <span class="c1">#=> nil</span>
<span class="no">Integer</span><span class="p">(</span><span class="s2">"z"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">nil</span><span class="p">)</span> <span class="c1">#>> ArgumentError: invalid value for Integer(): "z")</span>
</code></pre>
<p>But in most other cases where a boolean notion is concerned (for example, the <code>chomp</code> option in <code>Kernel#gets</code>), the distinction is between falsy vs. truthy values.</p>
<p>I request the distinction to be falsy vs. truthy. In other words, I would like the value <code>nil</code> to work on the falsy side rather than the truthy side like this.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Integer</span><span class="p">(</span><span class="s2">"z"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">false</span><span class="p">)</span> <span class="c1">#=> nil</span>
<span class="no">Integer</span><span class="p">(</span><span class="s2">"z"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">nil</span><span class="p">)</span> <span class="c1">#=> nil</span>
</code></pre> Ruby master - Feature #15945 (Open): Option to truncate in `String#ljust`, `String#rjust`, and `S...https://bugs.ruby-lang.org/issues/159452019-06-20T12:00:24Zsawa (Tsuyoshi Sawada)
<p>Sometimes, I need to adjust a string to an exact length: Pad if shorter, and truncate if longer. To do that, I need to combine two methods like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"12"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span> <span class="c1"># => "12***"</span>
<span class="s2">"1234567"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span> <span class="c1"># => "12345"</span>
<span class="s2">"xyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)[</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span> <span class="c1"># => "**xyz"</span>
<span class="s2">"stuvwxyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)[</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span> <span class="c1"># => "vwxyz"</span>
</code></pre>
<p>But that is messy, and needs a bit of thinking. It becomes even harder with centering.</p>
<p>I request an option on <code>String#ljust</code>, <code>String#rjust</code>, <code>String#center</code> to truncate the string when it is longer than the given length.</p>
<p>One way to do so may be: take a keyword <code>:truncate</code> or <code>:trunc</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"12"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "12***"</span>
<span class="s2">"1234567"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "12345"</span>
<span class="s2">"xyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "**xyz"</span>
<span class="s2">"stuvwxyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "vwxyz"</span>
<span class="s2">"abc"</span><span class="p">.</span><span class="nf">center</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "*abc*"</span>
<span class="s2">"abcdefg"</span><span class="p">.</span><span class="nf">center</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">,</span> <span class="ss">trunc: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => "bcdef"</span>
</code></pre>
<p>Another way is, when the length is negative, interpret it as truncating option.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"12"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "12***"</span>
<span class="s2">"1234567"</span><span class="p">.</span><span class="nf">ljust</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "12345"</span>
<span class="s2">"xyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "**xyz"</span>
<span class="s2">"stuvwxyz"</span><span class="p">.</span><span class="nf">rjust</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "vwxyz"</span>
<span class="s2">"abc"</span><span class="p">.</span><span class="nf">center</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "*abc*"</span>
<span class="s2">"abcdefg"</span><span class="p">.</span><span class="nf">center</span><span class="p">(</span><span class="o">-</span><span class="mi">5</span><span class="p">,</span> <span class="s2">"*"</span><span class="p">)</span> <span class="c1"># => "bcdef"</span>
</code></pre>
<p>But the second way changes the current behavior.</p> Ruby master - Bug #15708 (Rejected): Implicit numbered argument decomposes an arrayhttps://bugs.ruby-lang.org/issues/157082019-03-19T11:08:39Zsawa (Tsuyoshi Sawada)
<p>In the following, <code>@1</code> refers to the entire item iterated:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span> <span class="o">=</span> <span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">]</span>
<span class="n">a</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="n">x</span><span class="o">|</span> <span class="n">x</span><span class="p">}</span> <span class="c1"># => [1, 2, 3]</span>
<span class="n">a</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="err">@</span><span class="mi">1</span><span class="p">}</span> <span class="c1"># => [1, 2, 3]</span>
</code></pre>
<p>whereas in the following, <code>@1</code> refers to the first item achieved by decomposing the item iterated, behaving the same as <code>x</code> given by <code>|(x)|</code> rather than by <code>|x|</code>:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span> <span class="o">=</span> <span class="p">[[</span><span class="mi">1</span><span class="p">],</span> <span class="p">[</span><span class="mi">2</span><span class="p">],</span> <span class="p">[</span><span class="mi">3</span><span class="p">]]</span>
<span class="n">a</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="n">x</span><span class="o">|</span> <span class="n">x</span><span class="p">}</span> <span class="c1"># => [[1], [2], [3]]</span>
<span class="n">a</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="p">(</span><span class="n">x</span><span class="p">)</span><span class="o">|</span> <span class="n">x</span><span class="p">}</span> <span class="c1"># => [1, 2, 3]</span>
<span class="n">a</span><span class="p">.</span><span class="nf">map</span><span class="p">{</span><span class="err">@</span><span class="mi">1</span><span class="p">}</span> <span class="c1"># => [1, 2, 3]</span>
</code></pre>
<p>Is this intended?</p> Ruby master - Feature #15627 (Open): Appearance of custom singleton classeshttps://bugs.ruby-lang.org/issues/156272019-02-28T11:47:27Zsawa (Tsuyoshi Sawada)
<p>When I have a singleton class <code>AClass</code> of an instance <code>a</code> of a custom class <code>A</code>,</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">end</span>
<span class="n">a</span> <span class="o">=</span> <span class="no">A</span><span class="p">.</span><span class="nf">new</span>
<span class="no">AClass</span> <span class="o">=</span> <span class="n">a</span><span class="p">.</span><span class="nf">singleton_class</span>
</code></pre>
<p>i) even though the singleton class of <code>nil</code>, <code>false</code>, and <code>true</code> are referred to by their assigned constant names, the singleton class <code>AClass</code> of <code>a</code> is not:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="kp">nil</span><span class="p">.</span><span class="nf">singleton_class</span> <span class="c1">#=> NilClass</span>
<span class="kp">false</span><span class="p">.</span><span class="nf">singleton_class</span> <span class="c1">#=> FalseClass</span>
<span class="kp">true</span><span class="p">.</span><span class="nf">singleton_class</span> <span class="c1">#=> TrueClass</span>
<span class="n">a</span><span class="p">.</span><span class="nf">singleton_class</span> <span class="c1">#=> #<Class:#<A:0x00007fda832a7eb0>></span>
</code></pre>
<p>ii) even though the singleton class of <code>nil</code>, <code>false</code>, and <code>true</code> appear as their class, the singleton class <code>AClass</code> of <code>a</code> does not:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="kp">nil</span><span class="p">.</span><span class="nf">class</span> <span class="c1">#=> NilClass</span>
<span class="kp">false</span><span class="p">.</span><span class="nf">class</span> <span class="c1">#=> FalseClass</span>
<span class="kp">true</span><span class="p">.</span><span class="nf">class</span> <span class="c1">#=> TrueClass</span>
<span class="n">a</span><span class="p">.</span><span class="nf">class</span> <span class="c1">#=> A</span>
</code></pre>
<p>This contrast between <code>nil</code>, <code>false</code>, and <code>true</code> on the one hand and <code>a</code> on the other is confusing. I am actually not sure if this is intended behaviour It may be related to</p>
<ul>
<li><a href="https://bugs.ruby-lang.org/issues/15608" class="external">https://bugs.ruby-lang.org/issues/15608</a></li>
<li><a href="https://bugs.ruby-lang.org/issues/14895" class="external">https://bugs.ruby-lang.org/issues/14895</a></li>
</ul>
<p>I expect <code>AClass</code> to behave the same as with <code>NilClass</code>, <code>FalseClass</code>, and <code>TrueClass</code>. I expect:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span><span class="p">.</span><span class="nf">singleton_class</span> <span class="c1">#=> AClass</span>
<span class="n">a</span><span class="p">.</span><span class="nf">class</span> <span class="c1">#=> AClass</span>
</code></pre>
<p>If the current behaviour is intended, I would like this to become a feature request.</p> Ruby master - Feature #15562 (Open): `String#split` option to suppress the initial empty substringhttps://bugs.ruby-lang.org/issues/155622019-01-25T07:19:12Zsawa (Tsuyoshi Sawada)
<p><code>String#split</code> returns an empty substring if any at the beginning of the original string, even though it does not return an empty substring at the end of the original string:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">)</span> <span class="c1"># => ["", "b"]</span>
</code></pre>
<p>This is probably heritage from Perl or AWK, and may have some use cases, but in some (if not most) use cases, this looks asymmetric, and the initial empty string is unnatural and often requires some additional code to remove it. I propose to give an option to <code>String#split</code> to suppress it, perhaps like this (with <code>true</code> being the default):</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">initial_empty_string: </span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => ["b"]</span>
<span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">initial_empty_string: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => ["", "b"]</span>
<span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"ba"</span><span class="p">,</span> <span class="ss">initial_empty_string: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => ["b"]</span>
</code></pre>
<p>This does not mean to suppress empty strings in the middle. So it should work like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"aaaba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">initial_empty_string: </span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => ["", "", "b"]</span>
<span class="s2">"aaaba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">initial_empty_string: </span><span class="kp">true</span><span class="p">)</span> <span class="c1"># => ["", "", "", "b"]</span>
</code></pre>
<p>Or may be we can even go on further to control both the initial and the final ones like (with <code>:initial</code> being the default):</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">terminal_empty_string: :none</span><span class="p">)</span> <span class="c1"># => ["b"]</span>
<span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">terminal_empty_string: :initial</span><span class="p">)</span> <span class="c1"># => ["", "b"]</span>
<span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">terminal_empty_string: :final</span><span class="p">)</span> <span class="c1"># => ["b", ""]</span>
<span class="s2">"aba"</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="ss">terminal_empty_string: :both</span><span class="p">)</span> <span class="c1"># => ["", "b", ""]</span>
</code></pre> Ruby master - Feature #15557 (Open): A new class that stores a condition and the previous receiverhttps://bugs.ruby-lang.org/issues/155572019-01-23T09:15:54Zsawa (Tsuyoshi Sawada)
<p>I often see code like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">foo</span> <span class="o">=</span> <span class="n">default_definition</span>
<span class="n">foo</span> <span class="o">=</span> <span class="n">some_method</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span> <span class="k">if</span> <span class="n">some_condition</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="n">foo</span> <span class="o">=</span> <span class="n">another_method</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span> <span class="k">if</span> <span class="n">another_condition</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span>
<span class="o">...</span>
</code></pre>
<p>It would be nice if we can write this as a method chain. Since we now have the method <code>then</code>, I thought it would be a nice fit to introduce a method called <code>when</code>, such that putting it right in front of <code>then</code> would execute the <code>then</code> method as ordinarily only when the condition is satisfied, and returns the previous receiver otherwise so that the code above can be rewritten as:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">foo</span> <span class="o">=</span>
<span class="n">default_definition</span>
<span class="p">.</span><span class="nf">when</span><span class="p">{</span><span class="o">|</span><span class="n">foo</span><span class="o">|</span> <span class="n">some_condition</span><span class="p">(</span><span class="n">foo</span><span class="p">)}</span>
<span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="o">|</span><span class="n">foo</span><span class="o">|</span> <span class="n">some_method</span><span class="p">(</span><span class="n">foo</span><span class="p">)}</span>
<span class="p">.</span><span class="nf">when</span><span class="p">{</span><span class="o">|</span><span class="n">foo</span><span class="o">|</span> <span class="n">another_condition</span><span class="p">(</span><span class="n">foo</span><span class="p">)}</span>
<span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="o">|</span><span class="n">foo</span><span class="o">|</span> <span class="n">another_method</span><span class="p">(</span><span class="n">foo</span><span class="p">)}</span>
</code></pre>
<p>This proposal is also a generalization of what I intended to cover by <a href="https://bugs.ruby-lang.org/issues/13807" class="external">https://bugs.ruby-lang.org/issues/13807</a>. That is,</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span><span class="p">.</span><span class="nf">some_condition</span> <span class="p">?</span> <span class="n">a</span> <span class="p">:</span> <span class="n">b</span>
</code></pre>
<p>would rewritten as:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span><span class="p">.</span><span class="nf">when</span><span class="p">(</span><span class="o">&</span><span class="ss">:some_condition</span><span class="p">).</span><span class="nf">then</span><span class="p">{</span><span class="n">b</span><span class="p">}</span>
</code></pre>
<p>The proposal can be implemented by introducing a class called <code>Condition</code>, which stores a condition and the previous receiver, and works with <code>then</code> in a particular way.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">Object</span>
<span class="k">def</span> <span class="nf">when</span>
<span class="no">Condition</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="nb">self</span><span class="p">,</span> <span class="k">yield</span><span class="p">(</span><span class="nb">self</span><span class="p">))</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="k">class</span> <span class="nc">Condition</span>
<span class="k">def</span> <span class="nf">initialize</span> <span class="n">default</span><span class="p">,</span> <span class="n">condition</span>
<span class="vi">@default</span><span class="p">,</span> <span class="vi">@condition</span> <span class="o">=</span> <span class="n">default</span><span class="p">,</span> <span class="n">condition</span>
<span class="k">end</span>
<span class="k">def</span> <span class="nf">then</span>
<span class="vi">@condition</span> <span class="p">?</span> <span class="k">yield</span><span class="p">(</span><span class="vi">@default</span><span class="p">)</span> <span class="p">:</span> <span class="vi">@default</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>And additionally, if we introduce a negated method <code>unless</code> (or <code>else</code>) as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">Object</span>
<span class="k">def</span> <span class="nf">unless</span>
<span class="no">Condition</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="nb">self</span><span class="p">,</span> <span class="o">!</span><span class="k">yield</span><span class="p">(</span><span class="nb">self</span><span class="p">))</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>then we can use that for purposes such as validation of a variable as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">bar</span> <span class="o">=</span>
<span class="nb">gets</span>
<span class="p">.</span><span class="nf">unless</span><span class="p">{</span><span class="o">|</span><span class="n">bar</span><span class="o">|</span> <span class="n">some_validation</span><span class="p">(</span><span class="n">bar</span><span class="p">)}</span>
<span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="k">raise</span> <span class="s2">"The input is bad."</span><span class="p">}</span>
<span class="p">.</span><span class="nf">unless</span><span class="p">{</span><span class="o">|</span><span class="n">bar</span><span class="o">|</span> <span class="n">another_validation</span><span class="p">(</span><span class="n">bar</span><span class="p">)}</span>
<span class="p">.</span><span class="nf">then</span><span class="p">{</span><span class="k">raise</span> <span class="s2">"The input is bad in another way."</span><span class="p">}</span>
</code></pre> Ruby master - Feature #15523 (Open): Let `Range#begin` and `Range#end` be aliases of Range#first ...https://bugs.ruby-lang.org/issues/155232019-01-11T04:44:48Zsawa (Tsuyoshi Sawada)
<p>My understanding is that <code>Range#begin</code> and <code>Range#end</code>'s features are just subsets of <code>Range#first</code> and <code>Range#last</code>, respectively. And since they are slightly confusing with the keywords <code>begin</code> and <code>end</code>, I propose to either:</p>
<ul>
<li>Let <code>Range#begin</code> and <code>Range#end</code> be aliases of <code>Range#first</code> and <code>Range#last</code>, respectively, or</li>
<li>Let <code>Range#begin</code> and <code>Range#end</code> be obsolete after a migration path of waning against their use and recommending the use of <code>Range#first</code> and <code>Range#last</code> instead.</li>
</ul> Ruby master - Feature #15381 (Open): Let double splat call `to_h` implicitlyhttps://bugs.ruby-lang.org/issues/153812018-12-05T08:25:04Zsawa (Tsuyoshi Sawada)
<p>The single splat calls <code>to_a</code> implicitly on the object (if it is not an array already) so that, for example, we have the convenience of writing conditions in an array literal:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span> <span class="o">=</span> <span class="p">[</span>
<span class="o">*</span><span class="p">(</span><span class="ss">:foo</span> <span class="k">if</span> <span class="n">some_condition</span><span class="p">),</span>
<span class="o">*</span><span class="p">(</span><span class="ss">:bar</span> <span class="k">if</span> <span class="n">another_condition</span><span class="p">),</span>
<span class="p">]</span>
</code></pre>
<p>And the ampersand implicitly calls <code>to_proc</code> on the object (if it is not a proc already) so that we can substitute a block with an ampersand followed by a symbol:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">some_method</span><span class="p">(</span><span class="o">&</span><span class="ss">:some_method_name</span><span class="p">)</span>
</code></pre>
<p>Unlike the single splat and ampersand, the double splat does not seem to implicitly call a corresponding method. I propose that the double splat should call <code>to_h</code> implicitly on the object if it not already a Hash so that we can, for example, write a condition in a hash literal as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">h</span> <span class="o">=</span> <span class="p">{</span>
<span class="o">**</span><span class="p">({</span><span class="ss">a: </span><span class="mi">1</span><span class="p">}</span> <span class="k">if</span> <span class="n">some_condition</span><span class="p">),</span>
<span class="o">**</span><span class="p">({</span><span class="ss">b: </span><span class="mi">2</span><span class="p">)</span> <span class="k">if</span> <span class="n">another_condition</span><span class="p">),</span>
<span class="p">}</span>
</code></pre>
<p>There may be some other benefits of this feature that I have not noticed yet.</p> Ruby master - Feature #13314 (Open): dig=https://bugs.ruby-lang.org/issues/133142017-03-14T06:38:37Zsawa (Tsuyoshi Sawada)
<p>We have <code>Hash#dig</code>, and when we want to assign a key-value at a deep level, it is tempting to do:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">hash</span><span class="p">.</span><span class="nf">dig</span><span class="p">(</span><span class="ss">:key1</span><span class="p">,</span> <span class="ss">:key2</span><span class="p">,</span> <span class="ss">:key3</span><span class="p">,</span> <span class="ss">:key4</span><span class="p">)</span> <span class="o">=</span> <span class="s2">"value
</span></code></pre>
<p>when we actually needed to do:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">hash</span><span class="p">.</span><span class="nf">dig</span><span class="p">(</span><span class="ss">:key1</span><span class="p">,</span> <span class="ss">:key2</span><span class="p">,</span> <span class="ss">:key3</span><span class="p">)</span><span class="o">&</span><span class="p">.</span><span class="nf">[</span><span class="p">]</span><span class="o">=</span><span class="p">(</span><span class="ss">:key4</span><span class="p">,</span> <span class="s2">"value"</span><span class="p">)</span>
</code></pre>
<p>I propose a method <code>Hash#dig=</code>, which should be equivalent to the following:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">Hash</span>
<span class="k">def</span> <span class="nf">dig</span><span class="o">=</span><span class="p">(</span><span class="o">*</span><span class="n">keys</span><span class="p">,</span> <span class="n">final_key</span><span class="p">,</span> <span class="n">value</span><span class="p">)</span>
<span class="n">dig</span><span class="p">(</span><span class="o">*</span><span class="n">keys</span><span class="p">)</span><span class="o">&</span><span class="p">.</span><span class="nf">[</span><span class="p">](</span><span class="n">final_key</span><span class="p">,</span> <span class="n">value</span><span class="p">)</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre> Ruby master - Feature #13259 (Open): Kernel#Datehttps://bugs.ruby-lang.org/issues/132592017-02-28T02:17:56Zsawa (Tsuyoshi Sawada)
<p>I often see a piece of code like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="nb">require</span> <span class="s2">"date"</span>
<span class="k">begin</span>
<span class="no">Date</span><span class="p">.</span><span class="nf">strptime</span><span class="p">(</span><span class="n">some_string</span><span class="p">,</span> <span class="n">some_format</span><span class="p">)</span>
<span class="k">rescue</span>
<span class="kp">nil</span>
<span class="k">end</span>
</code></pre>
<p>Since we now have (<a href="https://bugs.ruby-lang.org/issues/12732" class="external">https://bugs.ruby-lang.org/issues/12732</a>) <code>Kernel#Integer</code> with a parameter to avoid raising an error in case of an invalid string, I think that having a counterpart of it in <code>Date</code> would be convenient. I propose <code>Kernel#Date</code>, which works like <code>Date.strptime</code> except that it takes an optional keyword argument, and works as follows:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Date</span><span class="p">(</span><span class="s2">"2017/02/02"</span><span class="p">,</span> <span class="s2">"%Y/%m/%d"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">nil</span><span class="p">)</span> <span class="c1"># => #<Date: 2017-02-02 ((2457787j,0s,0n),+0s,2299161j)></span>
<span class="no">Date</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">,</span> <span class="ss">exception: </span><span class="kp">nil</span><span class="p">)</span> <span class="c1"># => nil</span>
</code></pre> Ruby master - Bug #13162 (Rejected): tr does not recognize multi-byte characters correctlyhttps://bugs.ruby-lang.org/issues/131622017-01-27T05:33:47Zsawa (Tsuyoshi Sawada)
<p>This looks as expected:</p>
<pre><code>"\\".tr('\\', '\') # => "\"
</code></pre>
<p>but this doesn't:</p>
<pre><code>"\\".tr("\\¥'", "\¥'") # => "\\"
</code></pre>
<p>I confirmed the strings are UTF-8.</p> Ruby master - Feature #12648 (Open): `Enumerable#sort_by` with descending optionhttps://bugs.ruby-lang.org/issues/126482016-08-02T09:57:26Zsawa (Tsuyoshi Sawada)
<p>I would like to pass an optional argument to <code>Enumerable#sort_by</code> or <code>Enumerable#sort_by!</code> to allow descending sort. When the sort key is singular, this could be done by passing a single optinal boolean variable that represents ascending when <code>false</code> (default) and descending when <code>true</code>:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="o">&</span><span class="ss">:itself</span><span class="p">)</span> <span class="c1"># => [1, 2, 3]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">false</span><span class="p">,</span> <span class="o">&</span><span class="ss">:itself</span><span class="p">)</span> <span class="c1"># => [1, 2, 3]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">true</span><span class="p">,</span> <span class="o">&</span><span class="ss">:itself</span><span class="p">)</span> <span class="c1"># => [3, 2, 1]</span>
</code></pre>
<p>When there are multiple sort keys, corresponding numbers of arguments should be passed:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="n">e</span> <span class="o">%</span> <span class="mi">2</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [0, 2, 1, 3]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">false</span><span class="p">,</span> <span class="kp">false</span><span class="p">){</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="n">e</span> <span class="o">%</span> <span class="mi">2</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [0, 2, 1, 3]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">false</span><span class="p">,</span> <span class="kp">true</span><span class="p">){</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="n">e</span> <span class="o">%</span> <span class="mi">2</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [2, 0, 3, 1]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">true</span><span class="p">,</span> <span class="kp">false</span><span class="p">){</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="n">e</span> <span class="o">%</span> <span class="mi">2</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [1, 3, 0, 2]</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">(</span><span class="kp">true</span><span class="p">,</span> <span class="kp">true</span><span class="p">){</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="n">e</span> <span class="o">%</span> <span class="mi">2</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [3, 1, 2, 0]</span>
</code></pre> Ruby master - Feature #12523 (Open): `Object#values_at`https://bugs.ruby-lang.org/issues/125232016-06-27T14:59:57Zsawa (Tsuyoshi Sawada)
<p>It might be convenient to have a method that returns multiple attributes of an object.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span>
<span class="n">attr_accessors</span> <span class="ss">:foo</span><span class="p">,</span> <span class="ss">:bar</span><span class="p">,</span> <span class="ss">:baz</span>
<span class="k">def</span> <span class="nf">initialize</span> <span class="n">foo</span><span class="p">,</span> <span class="n">bar</span><span class="p">,</span> <span class="n">baz</span><span class="p">;</span> <span class="vi">@foo</span><span class="p">,</span> <span class="vi">@bar</span><span class="p">,</span> <span class="vi">@baz</span> <span class="o">=</span> <span class="n">foo</span><span class="p">,</span> <span class="n">bar</span><span class="p">,</span> <span class="n">baz</span> <span class="k">end</span>
<span class="k">end</span>
<span class="n">a</span> <span class="o">=</span> <span class="no">A</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">,</span> <span class="s2">"c"</span><span class="p">)</span>
<span class="n">a</span><span class="p">.</span><span class="nf">values_at</span><span class="p">(</span><span class="ss">:baz</span><span class="p">,</span> <span class="ss">:foo</span><span class="p">)</span> <span class="c1"># => ["c", "a"]</span>
</code></pre> Ruby master - Feature #12380 (Open): `Struct` as a subclass of `Class`https://bugs.ruby-lang.org/issues/123802016-05-14T06:22:27Zsawa (Tsuyoshi Sawada)
<p>This issue is somewhat of the same flavor as <a class="issue tracker-2 status-5 priority-4 priority-default closed" title="Feature: SingletonClass (Closed)" href="https://bugs.ruby-lang.org/issues/12374">#12374</a>.</p>
<p><code>Struct</code> has a constructor that creates a class:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Struct</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="ss">:foo</span><span class="p">)</span>
<span class="c1"># => #<Class:0x007f605f892cb0></span>
</code></pre>
<p>and this is the same situation with <code>Class</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Class</span><span class="p">.</span><span class="nf">new</span>
<span class="c1"># => #<Class:0x007f605f70c788></span>
</code></pre>
<p>Hence, most naturally, <code>Struct</code> should be a subclass of <code>Class</code>. But in reality, it isn't:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">Struct</span><span class="p">.</span><span class="nf">ancestors</span>
<span class="c1"># => [Struct, Enumerable, Object, Kernel, BasicObject]</span>
</code></pre>
<p>The current structure around <code>Struct</code> is counter-intuitive to me.</p>
<p>I propose that either <code>Struct</code> should be redefined as a subclass of <code>Class</code>, or a new class <code>StructClass</code> should be introduced as a subclass of <code>Class</code>, and take over the functionality of <code>Struct</code>.</p> Ruby master - Bug #12345 (Closed): A module's private constants are given with `Module#constant(f...https://bugs.ruby-lang.org/issues/123452016-05-03T22:05:25Zsawa (Tsuyoshi Sawada)
<p>A module's private constants are given with <code>Module#constant(false)</code>.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">A</span>
<span class="no">X</span> <span class="o">=</span> <span class="mi">1</span>
<span class="no">Y</span> <span class="o">=</span> <span class="mi">2</span>
<span class="n">private_constant</span> <span class="ss">:Y</span>
<span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span>
<span class="no">Z</span> <span class="o">=</span> <span class="mi">3</span>
<span class="no">W</span> <span class="o">=</span> <span class="mi">4</span>
<span class="n">private_constant</span> <span class="ss">:W</span>
<span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">constants</span> <span class="c1"># => [:X]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">constants</span><span class="p">(</span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => [:X, :Y]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span>
<span class="no">A</span><span class="p">.</span><span class="nf">constants</span> <span class="c1"># => [:X, :Z]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">constants</span><span class="p">(</span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => [:X, :Y]</span>
</code></pre>
<p>Besides this, I request a way to get the private constants of a module. I want:</p>
<pre><code class="ruby syntaxhl" data-language="ruby">
<span class="no">A</span><span class="p">.</span><span class="nf">private_constants</span> <span class="c1"># => [:Y]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">private_constants</span><span class="p">(</span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => [:Y]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span>
<span class="no">A</span><span class="p">.</span><span class="nf">private_constants</span> <span class="c1"># => [:Y, :W]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">private_constants</span><span class="p">(</span><span class="kp">false</span><span class="p">)</span> <span class="c1"># => [:Y]</span>
</code></pre> Ruby master - Feature #12319 (Open): `Module#const_get` does not accept symbol with nested namehttps://bugs.ruby-lang.org/issues/123192016-04-26T01:25:39Zsawa (Tsuyoshi Sawada)
<p><code>Module#const_get</code> accepts non-nested string, nested string, and non-nested symbol:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">class</span> <span class="nc">B</span><span class="p">;</span> <span class="k">class</span> <span class="nc">C</span> <span class="k">end</span> <span class="k">end</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">const_get</span><span class="p">(</span><span class="s2">"B"</span><span class="p">)</span> <span class="c1"># => A::B</span>
<span class="no">A</span><span class="p">.</span><span class="nf">const_get</span><span class="p">(</span><span class="s2">"B::C"</span><span class="p">)</span> <span class="c1"># => A::B::C</span>
<span class="no">A</span><span class="p">.</span><span class="nf">const_get</span><span class="p">(</span><span class="ss">:B</span><span class="p">)</span> <span class="c1"># => A::B</span>
</code></pre>
<p>but does not accept nested symbol:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">A</span><span class="p">.</span><span class="nf">const_get</span><span class="p">(</span><span class="ss">:"B::C"</span><span class="p">)</span> <span class="c1"># => NameError: wrong constant name B::C</span>
</code></pre>
<p>I would like this to be made possible.</p> Ruby master - Feature #12317 (Open): Name space of a modulehttps://bugs.ruby-lang.org/issues/123172016-04-26T00:15:58Zsawa (Tsuyoshi Sawada)
<p>I want a method to return the name space of a module, something like:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">module</span> <span class="nn">C</span> <span class="k">end</span> <span class="k">end</span> <span class="k">end</span>
<span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">.</span><span class="nf">namespace</span> <span class="o">=></span> <span class="p">[</span><span class="no">A</span><span class="p">,</span> <span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="p">,</span> <span class="no">A</span><span class="o">::</span><span class="no">B</span><span class="o">::</span><span class="no">C</span><span class="p">]</span>
</code></pre>
<p>There is <code>nesting</code> method that is similar, but that only returns the lexical nesting information.</p>
<p>There are also some known hacks for this, converting the module to the string representation using <code>to_s</code> or <code>name</code>, and then splitting it by <code>::</code>. But that easily breaks if the module is anonymous, or is a singleton module. I would like a more robust, core method.</p> Ruby master - Feature #12272 (Open): Accepting HTML entity name in string literalhttps://bugs.ruby-lang.org/issues/122722016-04-12T13:00:03Zsawa (Tsuyoshi Sawada)
<p>String literal allows the escape character <code>\u</code> to describe a character using UTF-8 character code like this:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"</span><span class="se">\u</span><span class="s2">201c"</span> <span class="c1"># left double quote</span>
<span class="s2">"</span><span class="se">\u</span><span class="s2">2191"</span> <span class="c1"># up arrow</span>
</code></pre>
<p>This is useful in typing characters that are not easy to input from the keyboard. However, normal people do not memorize the UTF-8 codes by heart.</p>
<p>The HTML symbol entity name is the place where we can compromise (although it is not available for the entire UTF-8), I think. I would like the string literal to be extended to accept HTML entity names and interpret them as the corresponding UTF-8 characters. I do not have a definite idea for the syntax, but a candidate can be an escape character <code>\& ... ;</code>, so that we can type:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"</span><span class="se">\&</span><span class="s2">ldquo;"</span> <span class="c1"># left double quote</span>
<span class="s2">"</span><span class="se">\&</span><span class="s2">uarr;"</span> <span class="c1"># up arrow</span>
</code></pre>
<p>Currently, <code>"\&"</code> is interpreted as <code>"&"</code>, so this will be a compatibility breaking change, and if that is not desirable, perhaps a different syntax may be considered.</p> Ruby master - Feature #12262 (Open): Anti-loophttps://bugs.ruby-lang.org/issues/122622016-04-08T07:21:19Zsawa (Tsuyoshi Sawada)
<p>The <code>loop</code> method continues by default, and requires the keyword <code>break</code> to escape. This is good when the continuing cases are the norm and the escaping cases are exceptional:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="kp">loop</span> <span class="k">do</span>
<span class="o">...</span>
<span class="k">if</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">break</span> <span class="c1"># breaks on exceptional cases</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">else</span>
<span class="o">...</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>But when the continuing cases are exceptional and the escaping cases are the norm, the construction requires a lot of <code>break</code>, and it becomes cumbersome:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="kp">loop</span> <span class="k">do</span>
<span class="o">...</span>
<span class="k">if</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">break</span> <span class="c1"># lot of breaks</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">break</span> <span class="c1"># lot of breaks</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">break</span> <span class="c1"># lot of breaks</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">else</span>
<span class="o">...</span>
<span class="k">break</span> <span class="c1"># lot of breaks</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>I actually see this use case a lot when user input is asked with validation on a command line script.</p>
<p>I request a <code>loop</code>-like method that works in the opposite way to <code>loop</code>, that is, it escapes (i.e., runs only once) by default, and requires a keyword to continue (perhaps <code>next</code>). The second code above would then be written like:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">some_loop_like_method</span> <span class="k">do</span>
<span class="o">...</span>
<span class="k">if</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">elsif</span> <span class="o">...</span>
<span class="o">...</span>
<span class="k">next</span> <span class="c1"># continues on exceptional cases</span>
<span class="k">else</span>
<span class="o">...</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre> Ruby master - Bug #12186 (Third Party's Issue): /snapshot/lib/rubygems/installer.rb:233https://bugs.ruby-lang.org/issues/121862016-03-17T09:03:34Zsawa (Tsuyoshi Sawada)
<p>I downloaded the nightly snapshot (<a href="https://cache.ruby-lang.org/pub/ruby/snapshot.tar.gz" class="external">https://cache.ruby-lang.org/pub/ruby/snapshot.tar.gz</a>), and did:</p>
<pre><code>./configure
make
sudo make install
</code></pre>
<p>and got:</p>
<pre><code>.../snapshot/lib/rubygems/installer.rb:233:in `check_executable_overwrite': no implicit conversion of nil into String (TypeError)
</code></pre>
<p>The offending line installer.rb:233 looks like this,</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">question</span> <span class="o"><<</span> <span class="n">existing</span>
</code></pre>
<p>and the values seem to be:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">question</span> <span class="c1"># => "rake's executable \"rake\" conflicts with "</span>
<span class="n">existing</span> <span class="c1"># => nil</span>
</code></pre>
<p>Is this a bug, or is there something wrong with my environment?</p>
<hr>
<p>Also, I am looking forward for Ruby 2.3.1. Is there a place where the schedule for the release of teeny versions are announced? Or is it is not announced until release?</p> Ruby master - Bug #12174 (Rejected): Interpolation ignores `to_s` (and `inspect`) when `to_s` is ...https://bugs.ruby-lang.org/issues/121742016-03-14T17:36:01Zsawa (Tsuyoshi Sawada)
<p>When <code>to_s</code> is defined to return <code>nil</code>, interpolation prints the original inspection.</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="k">class</span> <span class="nc">A</span>
<span class="k">def</span> <span class="nf">to_s</span><span class="p">;</span> <span class="k">end</span>
<span class="k">end</span>
<span class="nb">puts</span> <span class="s2">"</span><span class="si">#{</span><span class="no">A</span><span class="p">.</span><span class="nf">new</span><span class="si">}</span><span class="s2">"</span> <span class="c1"># => #<A:0x007f4edf19d720></span>
</code></pre>
<p>It even ignores an overwritten <code>inspect</code> definition.</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="k">class</span> <span class="nc">A</span>
<span class="k">def</span> <span class="nf">to_s</span><span class="p">;</span> <span class="k">end</span>
<span class="k">def</span> <span class="nf">inspect</span><span class="p">;</span> <span class="s2">"foo"</span> <span class="k">end</span>
<span class="k">end</span>
<span class="nb">puts</span> <span class="s2">"</span><span class="si">#{</span><span class="no">A</span><span class="p">.</span><span class="nf">new</span><span class="si">}</span><span class="s2">"</span> <span class="c1"># => #<A:0x007f8176c09050></span>
</code></pre> Ruby master - Feature #12173 (Open): `Time#till_now`https://bugs.ruby-lang.org/issues/121732016-03-14T16:57:25Zsawa (Tsuyoshi Sawada)
<p>It is very frequent to have a time instance:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">t</span> <span class="o">=</span> <span class="no">Time</span><span class="p">.</span><span class="nf">now</span>
</code></pre>
<p>and then after some operations, do:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="no">Time</span><span class="p">.</span><span class="nf">now</span> <span class="o">-</span> <span class="n">t</span>
</code></pre>
<p>I propose <code>Time#till_now</code>, which is equivalent to:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="k">class</span> <span class="nc">Time</span>
<span class="k">def</span> <span class="nf">till_now</span><span class="p">;</span> <span class="nb">self</span><span class="p">.</span><span class="nf">class</span><span class="p">.</span><span class="nf">now</span> <span class="o">-</span> <span class="nb">self</span> <span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>and similar methods can perhaps be defined on <code>Date</code> and <code>DateTime</code> classes as well. Another candidate for the method name is <code>until_now</code>.</p>
<p>Then we can do:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">t</span> <span class="o">=</span> <span class="no">Time</span><span class="p">.</span><span class="nf">now</span>
<span class="c1"># some heavy operation</span>
<span class="nb">puts</span> <span class="s2">"It took </span><span class="si">#{</span><span class="n">t</span><span class="p">.</span><span class="nf">till_now</span><span class="si">}</span><span class="s2"> secs."</span>
</code></pre> Ruby master - Feature #12145 (Open): Aliashood between `size` and `length` is not consistenthttps://bugs.ruby-lang.org/issues/121452016-03-05T19:12:01Zsawa (Tsuyoshi Sawada)
<p>When <code>size</code> and <code>length</code> have the same implementation, depending on the class, they are either independently defined methods, or the former is an alias of the latter. Particularly for <code>Array</code>:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="p">[].</span><span class="nf">method</span><span class="p">(</span><span class="ss">:size</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :length</span>
<span class="p">[].</span><span class="nf">method</span><span class="p">(</span><span class="ss">:length</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :length</span>
</code></pre>
<p>but for <code>Hash</code>, <code>String</code>, and <code>Symbol</code>:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="p">{}.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:size</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :size</span>
<span class="p">{}.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:length</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :length</span>
<span class="s2">""</span><span class="p">.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:size</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :size</span>
<span class="s2">""</span><span class="p">.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:length</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :length</span>
<span class="ss">:""</span><span class="p">.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:size</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :size</span>
<span class="ss">:""</span><span class="p">.</span><span class="nf">method</span><span class="p">(</span><span class="ss">:length</span><span class="p">).</span><span class="nf">original_name</span> <span class="c1"># => :length</span>
</code></pre>
<p>This might be a big issue, but since there is a standard Ruby method <code>original_name</code>, which returns different results, whether this being one way or another should matter. And I see no reason why they should behave differently. They should be unified in one way. Perhaps <code>Hash</code>, <code>String</code>, and <code>Symbol</code> should be made in the same way as with <code>Array</code>.</p> Ruby master - Feature #12134 (Open): Comparison between `true` and `false`https://bugs.ruby-lang.org/issues/121342016-03-02T10:56:01Zsawa (Tsuyoshi Sawada)
<p>There are some needs to sort elements depending on whether they satisfy certain condition expressed as a predicate. For example, to place prime numbers before others:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="nb">require</span> <span class="s2">"prime"</span>
<span class="p">[</span><span class="mi">7</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="no">Prime</span><span class="p">.</span><span class="nf">prime?</span><span class="p">(</span><span class="n">e</span><span class="p">)</span> <span class="p">?</span> <span class="mi">0</span> <span class="p">:</span> <span class="mi">1</span><span class="p">}</span> <span class="c1"># => [7, 5, 3, 2, 6, 4, 1]</span>
</code></pre>
<p>or to do such sort with the secondary condition to sort by the size:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="p">[</span><span class="mi">7</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="no">Prime</span><span class="p">.</span><span class="nf">prime?</span><span class="p">(</span><span class="n">e</span><span class="p">)</span> <span class="p">?</span> <span class="mi">0</span> <span class="p">:</span> <span class="mi">1</span><span class="p">,</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [2, 3, 5, 7, 1, 4, 6]</span>
</code></pre>
<p>Here, the temporal assignment of magic numbers <code>0</code> and <code>1</code> is ad hoc, but ordering between <code>true</code> and <code>false</code> makes sense. And given that there are <code>if</code> construction (which is unmarked case compared to the <code>unless</code> construction) and the ternary operator, in which the truthy branch is placed before the falsy branch, I think it makes sense to assume an inherent ordering of <code>true</code> being placed before <code>false</code>.</p>
<p>So I propose comparison between <code>true</code> and <code>false</code>:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="kp">true</span> <span class="o"><=></span> <span class="kp">false</span> <span class="c1"># => -1</span>
<span class="kp">false</span> <span class="o"><=></span> <span class="kp">true</span> <span class="c1"># => 1</span>
</code></pre>
<p>Using this, the cases above can be written more directly as:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="p">[</span><span class="mi">7</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="no">Prime</span><span class="p">.</span><span class="nf">prime?</span><span class="p">(</span><span class="n">e</span><span class="p">)}</span> <span class="c1"># => [7, 5, 3, 2, 6, 4, 1]</span>
<span class="p">[</span><span class="mi">7</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">sort_by</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="p">[</span><span class="no">Prime</span><span class="p">.</span><span class="nf">prime?</span><span class="p">(</span><span class="n">e</span><span class="p">),</span> <span class="n">e</span><span class="p">]}</span> <span class="c1"># => [2, 3, 5, 7, 1, 4, 6]</span>
</code></pre>
<hr>
<p>Please do not confuse this with the common proposal to map booleans to integers, particularly <code>true.to_i # => 1</code> and <code>false.to_i # => 0</code>. That is arbitrary, and does not make sense. In fact, my proposal goes against such proposal (under the proposal to map booleans, <code>true.to_i <=> false.to_i</code> translates to <code>1 <=> 0 # => 1</code>, which goes against my proposal <code>true <=> false # => 01</code>).</p> Ruby master - Bug #12128 (Rejected): Strings in `ARGV` are frozenhttps://bugs.ruby-lang.org/issues/121282016-02-29T18:08:15Zsawa (Tsuyoshi Sawada)
<p>It is not clear how the frozen status of strings in <code>ARGV</code> are to be described, but regardless of what I try to do (i.e. set frozen string pragma as false, which is probably irrelevant because the strings are already created at the time of file load), the strings appear frozen. I ran the following file <code>foo.rb</code> as <code>ruby foo.rb bar</code>:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="c1">#!/usr/bin/env ruby</span>
<span class="c1"># frozen_string_literal: false</span>
<span class="no">ARGV</span><span class="p">.</span><span class="nf">first</span><span class="p">.</span><span class="nf">frozen?</span> <span class="c1">#=> true</span>
<span class="no">ARGV</span><span class="p">.</span><span class="nf">first</span><span class="p">.</span><span class="nf">upcase!</span> <span class="c1">#=> can't modify frozen String (RuntimeError)</span>
</code></pre>
<p>I believe this is a bug. If not, I would like to know what determines the frozen status of the strings in <code>ARGV</code>. Is it a feature that they are always frozen?</p> Ruby master - Feature #12116 (Open): `Fixnum#divmod`, `Bignum#divmod` with multiple argumentshttps://bugs.ruby-lang.org/issues/121162016-02-26T18:04:45Zsawa (Tsuyoshi Sawada)
<p>Sometimes, I need to apply <code>divmod</code> repeatedly. For example, in order to convert a number expressing seconds into approx year, day, hour, minutes, seconds (approx in the sense of ignoring leap day and leap second), I can repeatedly apply <code>divmod</code>:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">seconds</span> <span class="o">=</span> <span class="mi">289342751</span>
<span class="n">minutes</span><span class="p">,</span> <span class="n">seconds</span> <span class="o">=</span> <span class="n">seconds</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">60</span><span class="p">)</span> <span class="c1"># => [4822379, 11]</span>
<span class="n">hours</span><span class="p">,</span> <span class="n">minutes</span> <span class="o">=</span> <span class="n">minutes</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">60</span><span class="p">)</span> <span class="c1"># => [80372, 59]</span>
<span class="n">days</span><span class="p">,</span> <span class="n">hours</span> <span class="o">=</span> <span class="n">hours</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">24</span><span class="p">)</span> <span class="c1"># => [3348, 20]</span>
<span class="n">years</span><span class="p">,</span> <span class="n">days</span> <span class="o">=</span> <span class="n">days</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">365</span><span class="p">)</span> <span class="c1"># => [9, 63]</span>
</code></pre>
<p>so that I get that 289342751 seconds is approx 9 years 63 days 20 hours 59 minutes and 11 seconds. But it is cumbersome to do all that. It would be convenient if <code>divmod</code> can take multiple arguments so that the conventional <code>divmod</code> is applied from the right-most argument to the left, returning the above result at once:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="mi">289342751</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">365</span><span class="p">,</span> <span class="mi">24</span><span class="p">,</span> <span class="mi">60</span><span class="p">,</span> <span class="mi">60</span><span class="p">)</span> <span class="c1"># => [9, 63, 20, 59, 11]</span>
</code></pre>
<p>In general, when <code>n</code> arguments are passed to the proposed <code>divmod</code>, an array of <code>n + 1</code> elements should be returned.</p>
<p>Another use case is nested arrays. Some people tend to express a matrix as a nested array, and try to access the innermost elements using multiple indices. To list the coordinates of the occurrences of <code>1</code>, one may do:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">m</span> <span class="o">=</span> <span class="p">[</span>
<span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">],</span>
<span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">],</span>
<span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">],</span>
<span class="p">]</span>
<span class="n">a</span> <span class="o">=</span> <span class="p">[]</span>
<span class="n">m</span><span class="p">.</span><span class="nf">each_with_index</span> <span class="k">do</span> <span class="o">|</span><span class="n">row</span><span class="p">,</span> <span class="n">i</span><span class="o">|</span>
<span class="n">row</span><span class="p">.</span><span class="nf">each_with_index</span> <span class="k">do</span> <span class="o">|</span><span class="n">e</span><span class="p">,</span> <span class="n">j</span><span class="o">|</span>
<span class="n">a</span><span class="p">.</span><span class="nf">push</span><span class="p">([</span><span class="n">i</span><span class="p">,</span> <span class="n">j</span><span class="p">])</span> <span class="k">if</span> <span class="n">e</span> <span class="o">==</span> <span class="mi">1</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="n">a</span> <span class="c1"># => [[0, 0], [1, 1], [2, 2]]</span>
</code></pre>
<p>But it is often easier to have a flat array and use <code>divmod</code> with it:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">m</span> <span class="o">=</span> <span class="p">[</span>
<span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span>
<span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span>
<span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span>
<span class="p">]</span>
<span class="n">m</span><span class="p">.</span><span class="nf">each</span><span class="p">.</span><span class="nf">with_index</span><span class="p">.</span><span class="nf">select</span><span class="p">{</span><span class="o">|</span><span class="n">e</span><span class="p">,</span> <span class="n">_</span><span class="o">|</span> <span class="n">e</span> <span class="o">==</span> <span class="mi">1</span><span class="p">}.</span><span class="nf">map</span><span class="p">{</span><span class="o">|</span><span class="n">_</span><span class="p">,</span> <span class="n">i</span><span class="o">|</span> <span class="n">i</span><span class="p">.</span><span class="nf">divmod</span><span class="p">(</span><span class="mi">3</span><span class="p">)}</span> <span class="c1"># => [[0, 0], [1, 1], [2, 2]]</span>
</code></pre>
<p>However, once the nesting achieves another level, it becomes cumbersome. Instead of using a nested array:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="n">t</span> <span class="o">=</span> <span class="p">[</span>
<span class="p">[</span>
<span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">],</span>
<span class="p">[</span><span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">],</span>
<span class="p">],</span>
<span class="p">[</span>
<span class="p">[</span><span class="s2">"a"</span><span class="p">,</span> <span class="s2">"b"</span><span class="p">],</span>
<span class="p">[</span><span class="s2">"c"</span><span class="p">,</span> <span class="s2">"d"</span><span class="p">],</span>
<span class="p">],</span>
<span class="p">]</span>
</code></pre>
<p>one can keep using a flat array, but that would require repeated application of <code>divmod</code> to covert between the flat index and the nested index. The proposed feature would also help in such case.</p> Ruby master - Bug #12108 (Rejected): Splitting an empty string returns an empty arrayhttps://bugs.ruby-lang.org/issues/121082016-02-24T15:56:15Zsawa (Tsuyoshi Sawada)
<p>Splitting an empty string returns an empty array.</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="s2">""</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">""</span><span class="p">)</span> <span class="c1"># => []</span>
<span class="s2">""</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="s2">"a"</span><span class="p">)</span> <span class="c1"># => []</span>
<span class="s2">""</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="sr">//</span><span class="p">)</span> <span class="c1"># => []</span>
<span class="s2">""</span><span class="p">.</span><span class="nf">split</span><span class="p">(</span><span class="sr">/a/</span><span class="p">)</span> <span class="c1"># => []</span>
</code></pre> Ruby master - Bug #12090 (Closed): `Range#cover` does not raise an exception when comparison failshttps://bugs.ruby-lang.org/issues/120902016-02-19T15:37:32Zsawa (Tsuyoshi Sawada)
<p>The documentation for <code>Range#cover?</code> says,</p>
<pre><code>cover?(obj) → true or false
Returns true if obj is between the begin and end of the range.
This tests begin <= obj <= end when exclude_end? is false and begin <= obj < end when exclude_end? is true.
</code></pre>
<p>which implies that, when comparison fails, <code>cover?</code> should raise an error. But actually, it doesn't:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="s2">"a"</span> <span class="o"><=</span> <span class="mi">1</span> <span class="c1"># => ArgumentError: comparison of String with 1 failed</span>
<span class="mi">1</span> <span class="o"><=</span> <span class="s2">"a"</span> <span class="c1"># => ArgumentError: comparison of Fixnum with String failed</span>
<span class="p">(</span><span class="s2">"a"</span><span class="o">..</span><span class="s2">"z"</span><span class="p">).</span><span class="nf">cover?</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="c1"># => false</span>
</code></pre>
<p>It silently returns <code>false</code> instead of raising an error.</p>
<p>Either <code>Range#cover?</code> should raise an error when comparison fails, or the documentation should be changed to correctly describe this behaviour.</p> Ruby master - Feature #12059 (Open): `Array#single?`, `Hash#single?`https://bugs.ruby-lang.org/issues/120592016-02-09T15:37:03Zsawa (Tsuyoshi Sawada)
<p>There are some use cases when one wants to check if an array or a hash has exactly one element. I propose <code>Array#single?</code> and <code>Hash#single?</code> that checks for such cases and returns either <code>true</code> or <code>false</code>. This is an analogy from the <code>empty?</code> method on the respective class.</p>
<ul>
<li>When creating an inflectional form out of an array:</li>
</ul>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">a</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"object1"</span><span class="p">,</span> <span class="s2">"object2"</span><span class="p">]</span>
<span class="s2">"There </span><span class="si">#{</span><span class="n">a</span><span class="p">.</span><span class="nf">single</span> <span class="p">?</span> <span class="s2">"is"</span> <span class="p">:</span> <span class="s2">"are"</span><span class="si">}</span><span class="s2"> </span><span class="si">#{</span><span class="n">a</span><span class="p">.</span><span class="nf">length</span><span class="si">}</span><span class="s2"> </span><span class="si">#{</span><span class="n">a</span><span class="p">.</span><span class="nf">single?</span> <span class="p">?</span> <span class="s2">"object"</span> <span class="p">:</span> <span class="s2">"objects"</span><span class="si">}</span><span class="s2">."</span>
<span class="c1"># => "There are 2 objects."</span>
</code></pre>
<ul>
<li>When checking if all elements of the array are the same:</li>
</ul>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">uniq</span><span class="p">.</span><span class="nf">single?</span> <span class="c1"># => false</span>
<span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">].</span><span class="nf">uniq</span><span class="p">.</span><span class="nf">single?</span> <span class="c1"># => true</span>
</code></pre> Ruby master - Bug #11991 (Closed): `Symbol#match` returns the match position, unlike `String#matc...https://bugs.ruby-lang.org/issues/119912016-01-14T22:20:45Zsawa (Tsuyoshi Sawada)
<p><code>String#match</code> and <code>Regexp#match</code> return a <code>MatchData</code> when match succeeds:</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="s2">""</span><span class="p">.</span><span class="nf">match</span><span class="p">(</span><span class="sr">//</span><span class="p">)</span> <span class="c1"># => #<MatchData ""></span>
<span class="sr">//</span><span class="p">.</span><span class="nf">match</span><span class="p">(</span><span class="s2">""</span><span class="p">)</span> <span class="c1"># => #<MatchData ""></span>
<span class="sr">//</span><span class="p">.</span><span class="nf">match</span><span class="p">(</span><span class="ss">:""</span><span class="p">)</span> <span class="c1"># => #<MatchData ""></span>
</code></pre>
<p>But <code>Symbol#match</code> returns the match position (like <code>String#=~</code>):</p>
<pre><code class="RUBY syntaxhl" data-language="RUBY"><span class="ss">:""</span><span class="p">.</span><span class="nf">match</span><span class="p">(</span><span class="sr">//</span><span class="p">)</span> <span class="c1"># => 0</span>
</code></pre>
<p>Thus, <code>Symbol#match</code> behaves differently from <code>String#match</code> and <code>Regexp#match</code>. This is the documented behavior, but it may be a bug (together with the documentation).</p>
<p>On the other hand, if it is not a bug, what is the rationale?</p> Ruby master - Feature #11939 (Open): Syntax sugar to apply a method replace a variablehttps://bugs.ruby-lang.org/issues/119392016-01-02T13:59:28Zsawa (Tsuyoshi Sawada)
<p>There is frequent use case to modify the value of a variable and keep it referred to by the same variable name. When method chaining cannot be done (for example, when the method is conditionally called), the same variable name would have to be repeated:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="n">var</span> <span class="o">=</span> <span class="n">var</span><span class="p">.</span><span class="nf">some_method</span><span class="p">(</span><span class="n">some_args</span><span class="p">)</span> <span class="k">if</span> <span class="n">some_condition</span>
<span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="o">...</span>
</code></pre>
<p>I would like to propose a syntax sugar for this kind of situation. I have two options in mind.</p>
<p>(1) <code>=.</code></p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="n">var</span> <span class="o">=</span><span class="p">.</span><span class="nf">some_method</span><span class="p">(</span><span class="n">some_args</span><span class="p">)</span> <span class="k">if</span> <span class="n">some_condition</span>
<span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="o">...</span>
</code></pre>
<p>(2) <code>.=</code></p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="n">var</span> <span class="p">.</span><span class="nf">=</span> <span class="n">some_method</span><span class="p">(</span><span class="n">some_args</span><span class="p">)</span> <span class="k">if</span> <span class="n">some_condition</span>
<span class="n">var</span> <span class="o">=</span> <span class="o">...</span>
<span class="o">...</span>
</code></pre>
<p>Notation (2) seems to be in line with syntax sugar like <code>+=</code>, but option (1) has the advantage that the period comes together with the method name.</p> Ruby master - Feature #11927 (Open): Return value for `Module#include` and `Module#prepend`https://bugs.ruby-lang.org/issues/119272015-12-30T11:40:36Zsawa (Tsuyoshi Sawada)
<p>Currently, <code>Module#include</code> and <code>Module#prepend</code> return the receiver, regardless of whether the ancestor chain has been modified. It is not straightforward to know whether it actually had effect.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">A</span><span class="p">;</span> <span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span> <span class="c1"># => A</span>
<span class="no">A</span><span class="p">.</span><span class="nf">ancestors</span> <span class="c1"># => [A, B]</span>
<span class="no">A</span><span class="p">.</span><span class="nf">prepend</span> <span class="no">B</span> <span class="c1"># => A</span>
<span class="no">A</span><span class="p">.</span><span class="nf">ancestors</span> <span class="c1"># => [A, B]</span>
</code></pre>
<p>I propose that, when <code>Module#include</code> and <code>Module#prepend</code> have no effect, they should either:</p>
<p>(1) return <code>nil</code><br>
(2) return <code>false</code>, or<br>
(3) raise an exception</p>
<p>This is similar to <code>Kernel#require</code>, which returns <code>false</code> when it has no effect. To make it parallel with <code>Kernel#require</code>, it might be even better to return <code>true</code> when <code>Module#include</code> and <code>Module#prepend</code> have effect, and <code>false</code> otherwise. It makes no sense to return the receiver because that is known.</p>
<p>Some relevant cases with expectations are:</p>
<ul>
<li>prepend after include</li>
</ul>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">A</span><span class="p">;</span> <span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span> <span class="c1"># => A/true</span>
<span class="no">A</span><span class="p">.</span><span class="nf">prepend</span> <span class="no">B</span> <span class="c1"># => nil/false/exception</span>
</code></pre>
<ul>
<li>include after prepend</li>
</ul>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">A</span><span class="p">;</span> <span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">prepend</span> <span class="no">B</span> <span class="c1"># => A/true</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span> <span class="c1"># => nil/false/exception</span>
</code></pre>
<ul>
<li>include/prepend after include/include at superclass</li>
</ul>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">A</span><span class="p">;</span> <span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">M</span> <span class="c1"># => A/true</span>
<span class="k">class</span> <span class="nc">B</span> <span class="o"><</span> <span class="no">A</span><span class="p">;</span> <span class="k">end</span>
<span class="no">B</span><span class="p">.</span><span class="nf">include</span> <span class="no">M</span> <span class="c1"># => nil/false/exception</span>
</code></pre> Ruby master - Bug #11878 (Rejected): Comparison of prepended moduleshttps://bugs.ruby-lang.org/issues/118782015-12-26T14:44:08Zsawa (Tsuyoshi Sawada)
<p>Including module <code>B</code> to class/module <code>A</code> gives the following results (as expected):</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">A</span><span class="p">;</span> <span class="k">end</span>
<span class="k">module</span> <span class="nn">B</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">include</span> <span class="no">B</span>
<span class="no">A</span> <span class="o"><</span> <span class="no">B</span> <span class="c1"># => true</span>
<span class="no">B</span> <span class="o"><</span> <span class="no">A</span> <span class="c1"># => false</span>
<span class="no">A</span> <span class="o"><=></span> <span class="no">B</span> <span class="c1"># => -1</span>
</code></pre>
<p>And prepending module <code>C</code> to <code>A</code> gives the following results:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">module</span> <span class="nn">C</span><span class="p">;</span> <span class="k">end</span>
<span class="no">A</span><span class="p">.</span><span class="nf">prepend</span> <span class="no">C</span>
<span class="no">A</span> <span class="o"><</span> <span class="no">C</span> <span class="c1"># => true</span>
<span class="no">C</span> <span class="o"><</span> <span class="no">A</span> <span class="c1"># => nil</span>
<span class="no">A</span> <span class="o"><=></span> <span class="no">C</span> <span class="c1"># => -1</span>
</code></pre>
<p>It looks like including and prepending almost do not make difference with respect to module comparison, i.e., <code>A < B</code> and <code>A < C</code> are the same, and <code>A <=> B</code> and <code>A <=> C</code> are the same. However, then, the difference between <code>B < A</code> and <code>C < A</code> stands out unexplained. I suppose this is a bug. If <code>C < A</code> were to return <code>false</code>, then it would be at least consistent.</p>
<p>However, if that was what was intended, then at least to me, it is strange. In that case, I would like to make this a feature request. I would rather expect:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">A</span> <span class="o"><</span> <span class="no">C</span> <span class="c1"># => false</span>
<span class="no">C</span> <span class="o"><</span> <span class="no">A</span> <span class="c1"># => true</span>
<span class="no">A</span> <span class="o"><=></span> <span class="no">C</span> <span class="c1"># => 1</span>
</code></pre> Ruby master - Bug #11871 (Closed): Heredoc unindentation with <<~ with single-quoted identifier f...https://bugs.ruby-lang.org/issues/118712015-12-25T16:20:10Zsawa (Tsuyoshi Sawada)
<p>Heredoc unindentation with <code><<~</code> works as expected when the identifier is bare or double-quoted:</p>
<pre><code>s = <<~_
fiwfewifjf
iofwejfweifwe
fjiofwejfweiof f
fiwejfweof
_
puts s
</code></pre>
<p>or</p>
<pre><code>s = <<~"_"
fiwfewifjf
iofwejfweifwe
fjiofwejfweiof f
fiwejfweof
_
puts s
</code></pre>
<p>Output:</p>
<pre><code>fiwfewifjf
iofwejfweifwe
fjiofwejfweiof f
fiwejfweof
</code></pre>
<p>But with a single-quoted identifier, the content is flushed left:</p>
<pre><code>s = <<~'_'
fiwfewifjf
iofwejfweifwe
fjiofwejfweiof f
fiwejfweof
_
puts s
</code></pre>
<p>Output:</p>
<pre><code>fiwfewifjf
iofwejfweifwe
fjiofwejfweiof f
fiwejfweof
</code></pre> Ruby master - Bug #11861 (Closed): `zip` with `&symbol` causes segmentation errorhttps://bugs.ruby-lang.org/issues/118612015-12-22T11:33:59Zsawa (Tsuyoshi Sawada)
<p>This code (<code>:foo</code> can be replaced with a different method, defined or not defined):</p>
<pre><code>[].zip([], &:foo)
</code></pre>
<p>causes a segmentation error:</p>
<pre><code>(irb):1: [BUG] Segmentation fault at 0x00000000e1112c
ruby 2.3.0preview2 (2015-12-11 trunk 53028) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0019 p:---- s:0076 e:000075 CFUNC :zip
c:0018 p:0012 s:0072 e:000071 EVAL (irb):1 [FINISH]
c:0017 p:---- s:0070 e:000069 CFUNC :eval
c:0016 p:0025 s:0063 e:000062 METHOD /usr/local/lib/ruby/2.3.0/irb/workspace.rb:86
c:0015 p:0027 s:0056 e:000054 METHOD /usr/local/lib/ruby/2.3.0/irb/context.rb:379
c:0014 p:0024 s:0050 e:000049 BLOCK /usr/local/lib/ruby/2.3.0/irb.rb:488
c:0013 p:0041 s:0042 e:000041 METHOD /usr/local/lib/ruby/2.3.0/irb.rb:622
c:0012 p:0011 s:0037 e:000036 BLOCK /usr/local/lib/ruby/2.3.0/irb.rb:485
c:0011 p:0128 s:0033 e:000032 BLOCK /usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:245 [FINISH]
c:0010 p:---- s:0030 e:000029 CFUNC :loop
c:0009 p:0009 s:0027 e:000026 BLOCK /usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:231 [FINISH]
c:0008 p:---- s:0025 e:000024 CFUNC :catch
c:0007 p:0018 s:0021 e:000020 METHOD /usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:230
c:0006 p:0037 s:0018 E:000570 METHOD /usr/local/lib/ruby/2.3.0/irb.rb:484
c:0005 p:0009 s:0015 e:000014 BLOCK /usr/local/lib/ruby/2.3.0/irb.rb:394 [FINISH]
c:0004 p:---- s:0013 e:000012 CFUNC :catch
c:0003 p:0177 s:0009 E:002630 METHOD /usr/local/lib/ruby/2.3.0/irb.rb:393
c:0002 p:0023 s:0004 E:000960 EVAL /usr/local/bin/irb:11 [FINISH]
c:0001 p:0000 s:0002 E:002480 (none) [FINISH]
-- Ruby level backtrace information ----------------------------------------
/usr/local/bin/irb:11:in `<main>'
/usr/local/lib/ruby/2.3.0/irb.rb:393:in `start'
/usr/local/lib/ruby/2.3.0/irb.rb:393:in `catch'
/usr/local/lib/ruby/2.3.0/irb.rb:394:in `block in start'
/usr/local/lib/ruby/2.3.0/irb.rb:484:in `eval_input'
/usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:230:in `each_top_level_statement'
/usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:230:in `catch'
/usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:231:in `block in each_top_level_statement'
/usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:231:in `loop'
/usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb:245:in `block (2 levels) in each_top_level_statement'
/usr/local/lib/ruby/2.3.0/irb.rb:485:in `block in eval_input'
/usr/local/lib/ruby/2.3.0/irb.rb:622:in `signal_status'
/usr/local/lib/ruby/2.3.0/irb.rb:488:in `block (2 levels) in eval_input'
/usr/local/lib/ruby/2.3.0/irb/context.rb:379:in `evaluate'
/usr/local/lib/ruby/2.3.0/irb/workspace.rb:86:in `evaluate'
/usr/local/lib/ruby/2.3.0/irb/workspace.rb:86:in `eval'
(irb):1:in `irb_binding'
(irb):1:in `zip'
-- Machine register context ------------------------------------------------
RIP: 0x00007f4f42c9eb09 RBP: 0x00007fff37becf50 RSP: 0x00007fff37bece90
RAX: 0x0000000000000000 RBX: 0x00007f4f4312ebb0 RCX: 0x00000000ffffffff
RDX: 0x0000000000e1110c RDI: 0x00007f4f4312eb50 RSI: 0x0000000000002007
R8: 0x00007f4f4438a960 R9: 0x00007f4f44325a00 R10: 0x00000000ffffffff
R11: 0x00007f4f4312ebb3 R12: 0x0000000000000000 R13: 0x0000000000000001
R14: 0x00007f4f4302f260 R15: 0x00007f4f4302f258 EFL: 0x0000000000010206
-- C level backtrace information -------------------------------------------
/usr/local/bin/ruby(rb_vm_bugreport+0x51f) [0x7f4f42e83d5f] vm_dump.c:688
/usr/local/bin/ruby(rb_bug_context+0xd0) [0x7f4f42e5fca0] error.c:423
/usr/local/bin/ruby(sigsegv+0x3e) [0x7f4f42d5c9ee] signal.c:890
/lib/x86_64-linux-gnu/libpthread.so.0 [0x7f4f4283b340]
/usr/local/bin/ruby(rb_block_arity+0x59) [0x7f4f42c9eb09] proc.c:958
/usr/local/bin/ruby(rb_ary_zip+0x176) [0x7f4f42e17326] array.c:3333
/usr/local/bin/ruby(vm_call_cfunc+0xf6) [0x7f4f42dddc96] vm_insnhelper.c:1709
/usr/local/bin/ruby(vm_call_method+0xe3) [0x7f4f42deaf23] vm_insnhelper.c:2241
/usr/local/bin/ruby(vm_exec_core+0x2026) [0x7f4f42de5786] insns.def:964
/usr/local/bin/ruby(vm_exec+0x81) [0x7f4f42de9361] vm.c:1637
/usr/local/bin/ruby(eval_string_with_cref+0x38c) [0x7f4f42dec63c] vm_eval.c:1359
/usr/local/bin/ruby(rb_f_eval+0x7f) [0x7f4f42decb0f] vm_eval.c:1398
/usr/local/bin/ruby(vm_call_cfunc+0xf6) [0x7f4f42dddc96] vm_insnhelper.c:1709
/usr/local/bin/ruby(vm_call_method+0xe3) [0x7f4f42deaf23] vm_insnhelper.c:2241
/usr/local/bin/ruby(vm_exec_core+0x20f9) [0x7f4f42de5859] insns.def:995
/usr/local/bin/ruby(vm_exec+0x81) [0x7f4f42de9361] vm.c:1637
/usr/local/bin/ruby(loop_i+0x14f) [0x7f4f42dec01f] vm.c:961
/usr/local/bin/ruby(rb_rescue2+0xc9) [0x7f4f42c97669] eval.c:799
/usr/local/bin/ruby(vm_call_cfunc+0xf6) [0x7f4f42dddc96] vm_insnhelper.c:1709
/usr/local/bin/ruby(vm_call_method+0xe3) [0x7f4f42deaf23] vm_insnhelper.c:2241
/usr/local/bin/ruby(vm_exec_core+0x2026) [0x7f4f42de5786] insns.def:964
/usr/local/bin/ruby(vm_exec+0x81) [0x7f4f42de9361] vm.c:1637
/usr/local/bin/ruby(catch_i+0x177) [0x7f4f42debd07] vm.c:961
/usr/local/bin/ruby(rb_catch_protect+0xaf) [0x7f4f42de061f] vm_eval.c:2013
/usr/local/bin/ruby(rb_f_catch+0x31) [0x7f4f42de07b1] vm_eval.c:1992
/usr/local/bin/ruby(vm_call_cfunc+0xf6) [0x7f4f42dddc96] vm_insnhelper.c:1709
/usr/local/bin/ruby(vm_call_method+0xe3) [0x7f4f42deaf23] vm_insnhelper.c:2241
/usr/local/bin/ruby(vm_exec_core+0x2026) [0x7f4f42de5786] insns.def:964
/usr/local/bin/ruby(vm_exec+0x81) [0x7f4f42de9361] vm.c:1637
/usr/local/bin/ruby(catch_i+0x177) [0x7f4f42debd07] vm.c:961
/usr/local/bin/ruby(rb_catch_protect+0xaf) [0x7f4f42de061f] vm_eval.c:2013
/usr/local/bin/ruby(rb_f_catch+0x31) [0x7f4f42de07b1] vm_eval.c:1992
/usr/local/bin/ruby(vm_call_cfunc+0xf6) [0x7f4f42dddc96] vm_insnhelper.c:1709
/usr/local/bin/ruby(vm_call_method+0xe3) [0x7f4f42deaf23] vm_insnhelper.c:2241
/usr/local/bin/ruby(vm_exec_core+0x2026) [0x7f4f42de5786] insns.def:964
/usr/local/bin/ruby(vm_exec+0x81) [0x7f4f42de9361] vm.c:1637
/usr/local/bin/ruby(ruby_exec_internal+0xc4) [0x7f4f42c930e4] eval.c:244
/usr/local/bin/ruby(ruby_run_node+0x2d) [0x7f4f42c96c4d] eval.c:309
/usr/local/bin/ruby(main+0x4b) [0x7f4f42c92d4b] addr2line.c:179
-- Other runtime information -----------------------------------------------
* Loaded script: irb
* Loaded features:
0 enumerator.so
1 thread.rb
2 rational.so
3 complex.so
4 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/encdb.so
5 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/trans/transdb.so
6 /usr/local/lib/ruby/2.3.0/unicode_normalize.rb
7 /usr/local/lib/ruby/2.3.0/x86_64-linux/rbconfig.rb
8 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/compatibility.rb
9 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/defaults.rb
10 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/deprecate.rb
11 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/errors.rb
12 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/version.rb
13 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/requirement.rb
14 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/platform.rb
15 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/basic_specification.rb
16 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/stub_specification.rb
17 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/util/list.rb
18 /usr/local/lib/ruby/2.3.0/x86_64-linux/stringio.so
19 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb
20 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/exceptions.rb
21 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_gem.rb
22 /usr/local/lib/ruby/2.3.0/monitor.rb
23 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb
24 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems.rb
25 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/path_support.rb
26 /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/dependency.rb
27 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/version.rb
28 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/core_ext/name_error.rb
29 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/levenshtein.rb
30 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/jaro_winkler.rb
31 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkable.rb
32 /usr/local/lib/ruby/2.3.0/delegate.rb
33 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
34 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
35 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkers/name_error_checkers.rb
36 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkers/method_name_checker.rb
37 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/spell_checkers/null_checker.rb
38 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean/formatter.rb
39 /usr/local/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0.rc1/lib/did_you_mean.rb
40 /usr/local/lib/ruby/2.3.0/e2mmap.rb
41 /usr/local/lib/ruby/2.3.0/irb/init.rb
42 /usr/local/lib/ruby/2.3.0/irb/workspace.rb
43 /usr/local/lib/ruby/2.3.0/irb/inspector.rb
44 /usr/local/lib/ruby/2.3.0/irb/context.rb
45 /usr/local/lib/ruby/2.3.0/irb/extend-command.rb
46 /usr/local/lib/ruby/2.3.0/irb/output-method.rb
47 /usr/local/lib/ruby/2.3.0/irb/notifier.rb
48 /usr/local/lib/ruby/2.3.0/irb/slex.rb
49 /usr/local/lib/ruby/2.3.0/irb/ruby-token.rb
50 /usr/local/lib/ruby/2.3.0/irb/ruby-lex.rb
51 /usr/local/lib/ruby/2.3.0/irb/src_encoding.rb
52 /usr/local/lib/ruby/2.3.0/irb/magic-file.rb
53 /usr/local/lib/ruby/2.3.0/x86_64-linux/readline.so
54 /usr/local/lib/ruby/2.3.0/irb/input-method.rb
55 /usr/local/lib/ruby/2.3.0/irb/locale.rb
56 /usr/local/lib/ruby/2.3.0/irb.rb
* Process memory map:
7f4f3f744000-7f4f405c3000 r--s 00000000 08:03 1441793 /usr/local/bin/ruby
7f4f405c3000-7f4f405d9000 r-xp 00000000 08:03 3014702 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4f405d9000-7f4f407d8000 ---p 00016000 08:03 3014702 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4f407d8000-7f4f407d9000 rw-p 00015000 08:03 3014702 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4f407d9000-7f4f407fe000 r-xp 00000000 08:03 3015032 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f4f407fe000-7f4f409fd000 ---p 00025000 08:03 3015032 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f4f409fd000-7f4f40a01000 r--p 00024000 08:03 3015032 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f4f40a01000-7f4f40a02000 rw-p 00028000 08:03 3015032 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f4f40a02000-7f4f40a3f000 r-xp 00000000 08:03 3014923 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f4f40a3f000-7f4f40c3f000 ---p 0003d000 08:03 3014923 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f4f40c3f000-7f4f40c41000 r--p 0003d000 08:03 3014923 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f4f40c41000-7f4f40c47000 rw-p 0003f000 08:03 3014923 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f4f40c47000-7f4f40c48000 rw-p 00000000 00:00 0
7f4f40c48000-7f4f40c4f000 r-xp 00000000 08:03 1628302 /usr/local/lib/ruby/2.3.0/x86_64-linux/readline.so
7f4f40c4f000-7f4f40e4f000 ---p 00007000 08:03 1628302 /usr/local/lib/ruby/2.3.0/x86_64-linux/readline.so
7f4f40e4f000-7f4f40e50000 r--p 00007000 08:03 1628302 /usr/local/lib/ruby/2.3.0/x86_64-linux/readline.so
7f4f40e50000-7f4f40e51000 rw-p 00008000 08:03 1628302 /usr/local/lib/ruby/2.3.0/x86_64-linux/readline.so
7f4f40e51000-7f4f40e58000 r-xp 00000000 08:03 1628305 /usr/local/lib/ruby/2.3.0/x86_64-linux/stringio.so
7f4f40e58000-7f4f41058000 ---p 00007000 08:03 1628305 /usr/local/lib/ruby/2.3.0/x86_64-linux/stringio.so
7f4f41058000-7f4f41059000 r--p 00007000 08:03 1628305 /usr/local/lib/ruby/2.3.0/x86_64-linux/stringio.so
7f4f41059000-7f4f4105a000 rw-p 00008000 08:03 1628305 /usr/local/lib/ruby/2.3.0/x86_64-linux/stringio.so
7f4f4105a000-7f4f4105c000 r-xp 00000000 08:03 1755447 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/trans/transdb.so
7f4f4105c000-7f4f4125c000 ---p 00002000 08:03 1755447 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/trans/transdb.so
7f4f4125c000-7f4f4125d000 r--p 00002000 08:03 1755447 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/trans/transdb.so
7f4f4125d000-7f4f4125e000 rw-p 00003000 08:03 1755447 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/trans/transdb.so
7f4f4125e000-7f4f41260000 r-xp 00000000 08:03 1755438 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/encdb.so
7f4f41260000-7f4f4145f000 ---p 00002000 08:03 1755438 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/encdb.so
7f4f4145f000-7f4f41460000 r--p 00001000 08:03 1755438 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/encdb.so
7f4f41460000-7f4f41461000 rw-p 00002000 08:03 1755438 /usr/local/lib/ruby/2.3.0/x86_64-linux/enc/encdb.so
7f4f41461000-7f4f41d23000 r--p 00000000 08:03 1183304 /usr/lib/locale/locale-archive
7f4f41d23000-7f4f41ede000 r-xp 00000000 08:03 3034899 /lib/x86_64-linux-gnu/libc-2.19.so
7f4f41ede000-7f4f420dd000 ---p 001bb000 08:03 3034899 /lib/x86_64-linux-gnu/libc-2.19.so
7f4f420dd000-7f4f420e1000 r--p 001ba000 08:03 3034899 /lib/x86_64-linux-gnu/libc-2.19.so
7f4f420e1000-7f4f420e3000 rw-p 001be000 08:03 3034899 /lib/x86_64-linux-gnu/libc-2.19.so
7f4f420e3000-7f4f420e8000 rw-p 00000000 00:00 0
7f4f420e8000-7f4f421ed000 r-xp 00000000 08:03 3014710 /lib/x86_64-linux-gnu/libm-2.19.so
7f4f421ed000-7f4f423ec000 ---p 00105000 08:03 3014710 /lib/x86_64-linux-gnu/libm-2.19.so
7f4f423ec000-7f4f423ed000 r--p 00104000 08:03 3014710 /lib/x86_64-linux-gnu/libm-2.19.so
7f4f423ed000-7f4f423ee000 rw-p 00105000 08:03 3014710 /lib/x86_64-linux-gnu/libm-2.19.so
7f4f423ee000-7f4f423f7000 r-xp 00000000 08:03 3014789 /lib/x86_64-linux-gnu/libcrypt-2.19.so
7f4f423f7000-7f4f425f7000 ---p 00009000 08:03 3014789 /lib/x86_64-linux-gnu/libcrypt-2.19.so
7f4f425f7000-7f4f425f8000 r--p 00009000 08:03 3014789 /lib/x86_64-linux-gnu/libcrypt-2.19.so
7f4f425f8000-7f4f425f9000 rw-p 0000a000 08:03 3014789 /lib/x86_64-linux-gnu/libcrypt-2.19.so
7f4f425f9000-7f4f42627000 rw-p 00000000 00:00 0
7f4f42627000-7f4f4262a000 r-xp 00000000 08:03 3014763 /lib/x86_64-linux-gnu/libdl-2.19.so
7f4f4262a000-7f4f42829000 ---p 00003000 08:03 3014763 /lib/x86_64-linux-gnu/libdl-2.19.so
7f4f42829000-7f4f4282a000 r--p 00002000 08:03 3014763 /lib/x86_64-linux-gnu/libdl-2.19.so
7f4f4282a000-7f4f4282b000 rw-p 00003000 08:03 3014763 /lib/x86_64-linux-gnu/libdl-2.19.so
7f4f4282b000-7f4f42844000 r-xp 00000000 08:03 3034900 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f42844000-7f4f42a43000 ---p 00019000 08:03 3034900 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f42a43000-7f4f42a44000 r--p 00018000 08:03 3034900 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f42a44000-7f4f42a45000 rw-p 00019000 08:03 3034900 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f42a45000-7f4f42a49000 rw-p 00000000 00:00 0
7f4f42a49000-7f4f42a6c000 r-xp 00000000 08:03 3015621 /lib/x86_64-linux-gnu/ld-2.19.so
7f4f42aa9000-7f4f42c6b000 r--s 00000000 08:03 3034899 /lib/x86_64-linux-gnu/libc-2.19.so
7f4f42c6b000-7f4f42c6c000 r--p 00022000 08:03 3015621 /lib/x86_64-linux-gnu/ld-2.19.so
7f4f42c6c000-7f4f42c6d000 rw-p 00023000 08:03 3015621 /lib/x86_64-linux-gnu/ld-2.19.so
7f4f42c6d000-7f4f42c6e000 rw-p 00000000 00:00 0
7f4f42c6e000-7f4f42f55000 r-xp 00000000 08:03 1441793 /usr/local/bin/ruby
7f4f42f65000-7f4f4300c000 r--s 00000000 08:03 1198073 /usr/lib/debug/lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f4300c000-7f4f4302f000 r--s 00000000 08:03 3034900 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f4f4302f000-7f4f43134000 rw-p 00000000 00:00 0
7f4f43144000-7f4f43147000 rw-p 00000000 00:00 0
7f4f43147000-7f4f4314e000 r--s 00000000 08:03 1457857 /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
7f4f4314e000-7f4f4314f000 ---p 00000000 00:00 0
7f4f4314f000-7f4f43154000 rw-p 00000000 00:00 0 [stack:7161]
7f4f43154000-7f4f43159000 r--p 002e6000 08:03 1441793 /usr/local/bin/ruby
7f4f43159000-7f4f4315a000 rw-p 002eb000 08:03 1441793 /usr/local/bin/ruby
7f4f4315a000-7f4f4316c000 rw-p 00000000 00:00 0
7f4f44324000-7f4f44856000 rw-p 00000000 00:00 0 [heap]
7fff373a2000-7fff37bf1000 rw-p 00000000 00:00 0
7fff37bf4000-7fff37bf6000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
</code></pre> Ruby master - Bug #11860 (Closed): Double splat does not work on empty hash assigned via variablehttps://bugs.ruby-lang.org/issues/118602015-12-22T08:33:54Zsawa (Tsuyoshi Sawada)
<p>When an empty hash is given as a literal, the double splat operates on it, and leaves nothing, which is expected.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">String</span>
<span class="k">def</span> <span class="nf">foo</span><span class="p">;</span> <span class="k">end</span>
<span class="k">end</span>
<span class="p">[</span><span class="o">**</span><span class="p">{}]</span> <span class="c1"># => []</span>
<span class="s2">"foo"</span><span class="p">.</span><span class="nf">foo</span><span class="p">(</span><span class="o">**</span><span class="p">{})</span> <span class="c1"># => nil</span>
<span class="s2">"foo"</span><span class="p">.</span><span class="nf">send</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">,</span> <span class="o">**</span><span class="p">{})</span> <span class="c1"># => nil</span>
</code></pre>
<p>However, when an empty hash is given via variable, the double splat retains an empty hash in place.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">h</span> <span class="o">=</span> <span class="p">{}</span>
<span class="p">[</span><span class="o">**</span><span class="n">h</span><span class="p">]</span> <span class="c1"># => [{}]</span>
<span class="s2">"foo"</span><span class="p">.</span><span class="nf">foo</span><span class="p">(</span><span class="o">**</span><span class="n">h</span><span class="p">)</span> <span class="c1"># => wrong number of arguments (given 1, expected 0)</span>
<span class="s2">"foo"</span><span class="p">.</span><span class="nf">send</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">,</span> <span class="o">**</span><span class="n">h</span><span class="p">)</span> <span class="c1"># => wrong number of arguments (given 1, expected 0)</span>
</code></pre> Ruby master - Bug #11805 (Closed): Cannot run Rubyhttps://bugs.ruby-lang.org/issues/118052015-12-11T10:24:09Zsawa (Tsuyoshi Sawada)
<p>I installed the new Ruby, and tried to run Ruby, but it raises the following error.</p>
<p>(Since I installed Ruby 2.3.0preview1, it had a bug, and I had not been able to run Ruby, and now, after having waited for a month, I installed the new one, and there still is a bug. Disappointed a little bit.)</p>
<pre><code>/usr/local/lib/ruby/site_ruby/2.3.0/rubygems/stub_specification.rb:112:in `initialize': Permission denied @ rb_sysopen - /usr/local/lib/ruby/gems/2.3.0/specifications/did_you_mean-1.0.0.beta3.gemspec (Errno::EACCES)
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/stub_specification.rb:112:in `open'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/stub_specification.rb:112:in `data'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/stub_specification.rb:203:in `valid?'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:748:in `select'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:748:in `gemspec_stubs_in'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:773:in `block in map_stubs'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:770:in `each'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:770:in `flat_map'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:770:in `map_stubs'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:762:in `installed_stubs'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:830:in `stubs'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:1035:in `find_by_path'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems.rb:188:in `try_activate'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:124:in `rescue in require'
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:39:in `require'
from <internal:gem_prelude>:6:in `<internal:gem_prelude>'
</code></pre> Ruby master - Bug #11691 (Closed): Permission denied @ rb_sysopen did_you_mean-1.0.0.beta3.gemspechttps://bugs.ruby-lang.org/issues/116912015-11-15T16:47:07Zsawa (Tsuyoshi Sawada)
<p>When I ruby Ruby, I get this error:</p>
<pre><code>/usr/local/lib/ruby/2.3.0/rubygems/stub_specification.rb:80:in `initialize': Permission denied @ rb_sysopen - /usr/local/lib/ruby/gems/2.3.0/specifications/did_you_mean-1.0.0.beta3.gemspec (Errno::EACCES)
from /usr/local/lib/ruby/2.3.0/rubygems/stub_specification.rb:80:in `open'
from /usr/local/lib/ruby/2.3.0/rubygems/stub_specification.rb:80:in `data'
from /usr/local/lib/ruby/2.3.0/rubygems/stub_specification.rb:186:in `valid?'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:749:in `select'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:749:in `gemspec_stubs_in'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:755:in `block in map_stubs'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:755:in `each'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:755:in `flat_map'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:755:in `map_stubs'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:806:in `stubs'
from /usr/local/lib/ruby/2.3.0/rubygems/specification.rb:1009:in `find_by_path'
from /usr/local/lib/ruby/2.3.0/rubygems.rb:188:in `try_activate'
from /usr/local/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:126:in `rescue in require'
from /usr/local/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:39:in `require'
from <internal:gem_prelude>:4:in `<compiled>'
</code></pre> Ruby master - Bug #11471 (Closed): min, min_by, max, max_by with optional parameter return a wron...https://bugs.ruby-lang.org/issues/114712015-08-20T17:51:06Zsawa (Tsuyoshi Sawada)
<p>This is reported in StackOverflow: <a href="http://stackoverflow.com/questions/32121749/why-20-13-14-min2-13-20" class="external">http://stackoverflow.com/questions/32121749/why-20-13-14-min2-13-20</a>. Sometimes <code>min</code>, <code>min_by</code>, <code>max</code>, <code>max_by</code> with an optional parameter return a wrong value.</p>
<pre><code>[20, 32, 32, 21, 30, 25, 29, 13, 14].min(2) # => [13, 20]
[20, 32, 32, 21, 30, 25, 29, 13, 14].min_by(2, &:itself) # => [13, 20]
[0, 0, 0, 0, 0, 0, 1, 3, 2].max(2) # => [3, 1]
[0, 0, 0, 0, 0, 0, 1, 3, 2].max_by(2, &:itself) # => [3, 1]
</code></pre> Ruby master - Feature #11309 (Open): Iterator over string matcheshttps://bugs.ruby-lang.org/issues/113092015-06-26T14:55:43Zsawa (Tsuyoshi Sawada)
<p>This was hinted from a problem in stackoverflow (<a href="http://stackoverflow.com/questions/31074050/build-list-of-strings-containing-substrings-separated-by-an-from-a-string/31075511#31075511" class="external">http://stackoverflow.com/questions/31074050/build-list-of-strings-containing-substrings-separated-by-an-from-a-string/31075511#31075511</a>).</p>
<p>Suppose there is a string:</p>
<pre><code>s = "a_b_c_d_e"
</code></pre>
<p>To get an array of pre-matches that result from matching <code>s</code> with <code>"_"</code>, I can do this:</p>
<pre><code>a = []
s.scan("_"){a.push($`)}
a # => ["a", "a_b", "a_b_c", "a_b_c_d"]
</code></pre>
<p>But this looks too Perlish. I thought it would be nice if there is a method on <code>String</code> that creates an enumerator over matches so that I can do something like this:</p>
<pre><code>"a_b_c_d_e".some_method("_").with_object([]){|m, a| a.push(m.post_match)}
# => ["a", "a_b", "a_b_c", "a_b_c_d"]
</code></pre>
<p>where <code>m</code> is the last matchdata instance at that point. I believe such method would have wider application.</p> Ruby master - Bug #10845 (Closed): Subclassing Stringhttps://bugs.ruby-lang.org/issues/108452015-02-10T23:41:25Zsawa (Tsuyoshi Sawada)
<p>If I make a subclass of <code>String</code>, the method <code>*</code> returns an instance of that class.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">MyString</span> <span class="o"><</span> <span class="no">String</span>
<span class="k">end</span>
<span class="no">MyString</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">).</span><span class="nf">*</span><span class="p">(</span><span class="mi">2</span><span class="p">).</span><span class="nf">class</span> <span class="c1">#=> MyString</span>
</code></pre>
<p>This is different from other similar operations like <code>+</code> and <code>%</code>, which return a <code>String</code> instance.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="no">MyString</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">).</span><span class="nf">+</span><span class="p">(</span><span class="s2">"bar"</span><span class="p">).</span><span class="nf">class</span> <span class="c1">#=> String</span>
<span class="no">MyString</span><span class="p">.</span><span class="nf">new</span><span class="p">(</span><span class="s2">"%{foo}"</span><span class="p">).</span><span class="nf">%</span><span class="p">(</span><span class="ss">foo: </span><span class="s2">"bar"</span><span class="p">).</span><span class="nf">class</span> <span class="c1">#=> String</span>
</code></pre>
<p>I don't see clear reason why <code>*</code> is to be different from <code>+</code> and <code>%</code>, and thought that perhaps either the behaviour with <code>*</code> is a bug, or the behaviour with <code>+</code> and <code>%</code> is a bug.</p>
<p>Or, is a reason why they are different?</p> Ruby master - Feature #10729 (Open): Array method to subtract in placehttps://bugs.ruby-lang.org/issues/107292015-01-10T22:36:02Zsawa (Tsuyoshi Sawada)
<p>I request a method on array that takes another array, subtract that from self in place (= destructively), and return the subtracted elements:</p>
<pre><code>a = [1, 2, 3, 4, 5]
a.some_method([2, 4, 6]) #=> [2, 4]
a #=> [1, 3, 5]
</code></pre>
<p>Ideally, it should also allow a block:</p>
<pre><code>a = [1, 2, 3, 4, 5]
a.some_method(&:even?) #=> [2, 4]
a #=> [1, 3, 5]
</code></pre>
<p>This operation is quite frequent, but at the moment, it requires several steps to do.</p> Ruby master - Feature #10426 (Open): A predicate to express congruencehttps://bugs.ruby-lang.org/issues/104262014-10-26T00:55:20Zsawa (Tsuyoshi Sawada)
<p>I occasionally felt the necessity of a predicate that checks congruence with respect to some operations:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">Object</span>
<span class="k">def</span> <span class="nf">equal_by?</span> <span class="n">other</span><span class="p">,</span> <span class="o">&</span><span class="n">pr</span>
<span class="n">pr</span><span class="p">.</span><span class="nf">call</span><span class="p">(</span><span class="nb">self</span><span class="p">)</span> <span class="o">==</span> <span class="n">pr</span><span class="p">.</span><span class="nf">call</span><span class="p">(</span><span class="n">other</span><span class="p">)</span>
<span class="k">end</span>
<span class="k">alias</span> <span class="n">congruent?</span> <span class="n">equal_by?</span>
<span class="k">end</span>
<span class="mi">5</span><span class="p">.</span><span class="nf">congruent?</span><span class="p">(</span><span class="mi">2</span><span class="p">){</span><span class="o">|</span><span class="n">e</span><span class="o">|</span> <span class="n">e</span> <span class="o">%</span> <span class="mi">3</span><span class="p">}</span> <span class="c1">#=> true</span>
<span class="s2">"HELLO"</span><span class="p">.</span><span class="nf">equal_by?</span><span class="p">(</span><span class="s2">"Hello"</span><span class="p">,</span> <span class="o">&</span><span class="ss">:downcase</span><span class="p">)</span> <span class="c1">#=> true</span>
</code></pre> Ruby master - Feature #10425 (Open): A predicate method to tell if a number is near anotherhttps://bugs.ruby-lang.org/issues/104252014-10-26T00:38:58Zsawa (Tsuyoshi Sawada)
<p>A method <code>near?</code> like the following would be useful.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="k">class</span> <span class="nc">Numeric</span>
<span class="k">def</span> <span class="nf">near?</span> <span class="n">other</span><span class="p">,</span> <span class="ss">delta: </span><span class="no">Float</span><span class="o">::</span><span class="no">EPSILON</span>
<span class="p">(</span><span class="n">other</span><span class="p">.</span><span class="nf">to_f</span> <span class="o">-</span> <span class="n">to_f</span><span class="p">).</span><span class="nf">abs</span> <span class="o"><=</span> <span class="n">delta</span><span class="p">.</span><span class="nf">to_f</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="k">class</span> <span class="nc">Time</span>
<span class="k">def</span> <span class="nf">near?</span> <span class="n">other</span><span class="p">,</span> <span class="ss">delta: </span><span class="no">Float</span><span class="o">::</span><span class="no">EPSILON</span>
<span class="n">to_f</span><span class="p">.</span><span class="nf">near?</span><span class="p">(</span><span class="n">other</span><span class="p">.</span><span class="nf">to_f</span><span class="p">,</span> <span class="ss">delta: </span><span class="n">delta</span><span class="p">)</span>
<span class="k">end</span>
<span class="k">end</span>
</code></pre>
<p>It can be used to check errors, or whether something is around something.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mf">23.24324</span><span class="p">.</span><span class="nf">near?</span><span class="p">(</span><span class="mf">23.23</span><span class="p">,</span> <span class="ss">delta: </span><span class="mf">0.5</span><span class="p">)</span> <span class="c1"># => true</span>
<span class="n">t1</span> <span class="o">=</span> <span class="n">t2</span> <span class="o">=</span> <span class="no">Time</span><span class="p">.</span><span class="nf">now</span>
<span class="n">t3</span> <span class="o">=</span> <span class="no">Time</span><span class="p">.</span><span class="nf">now</span>
<span class="n">t1</span><span class="p">.</span><span class="nf">near?</span><span class="p">(</span><span class="n">t2</span><span class="p">)</span> <span class="c1">#=> true</span>
<span class="n">t1</span><span class="p">.</span><span class="nf">near?</span><span class="p">(</span><span class="n">t3</span><span class="p">)</span> <span class="c1">#=> false</span>
<span class="mi">5</span><span class="p">.</span><span class="nf">near?</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="ss">delta: </span><span class="mi">1</span><span class="p">)</span> <span class="c1">#=> true</span>
</code></pre>
<p>Some testing frameworks have something similar to this, but I think this is an elementary concept that Ruby should support at it core.</p> Ruby master - Bug #10422 (Closed): RDoc for BasicObject has methods that do not existhttps://bugs.ruby-lang.org/issues/104222014-10-23T07:44:37Zsawa (Tsuyoshi Sawada)
<p>RDoc for BasicObject (<a href="http://www.ruby-doc.org/core-2.1.3/BasicObject.html" class="external">http://www.ruby-doc.org/core-2.1.3/BasicObject.html</a>) has descriptions for methods <code>object_id</code> and <code>send</code>, which do not exist. Also, <code>send</code> and <code>__send__</code> are listed twice.</p> Ruby master - Feature #10366 (Open): New inspection form for rationalhttps://bugs.ruby-lang.org/issues/103662014-10-11T00:50:15Zsawa (Tsuyoshi Sawada)
<p>Currently, rational inspection is expressed with parentheses:</p>
<pre><code>(2/51)
</code></pre>
<p>If this were taken as a Ruby expression, it would mean integer division, whose value is <code>0</code> in this case. It does not make much sense to express that it is indeed not integer division and that it is rational by using parentheses. Now that we have rational literal using <code>r</code>, we can make the inspection form as:</p>
<pre><code>2/51r
</code></pre>
<p>This would be much less confusing.</p> Ruby master - Feature #10332 (Open): Rational literal for mixed fractionshttps://bugs.ruby-lang.org/issues/103322014-10-06T14:55:48Zsawa (Tsuyoshi Sawada)
<p>Current behavior of rational literal and <code>String#to_r</code> does not recognize mixed fractions. Mixed fraction is not rare, and is frequently used in places such as US length measurement.</p>
<p><img src="http://www.strongtie.com/graphics/anchorsystems/catalog/tables/217b-2012.gif" alt="drill bits"></p>
<p>I propose that rational literal and <code>String#to_r</code> should be extended to handle mixed fractions. Perhaps something like:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="mi">8</span> <span class="mi">1</span><span class="o">/</span><span class="mi">2</span><span class="n">r</span> <span class="c1">#=> (17/2)</span>
<span class="s2">"8 1/2"</span><span class="p">.</span><span class="nf">to_r</span> <span class="c1">#=> (17/2)</span>
</code></pre>
<p>or</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="p">(</span><span class="mi">8</span> <span class="mi">1</span><span class="o">/</span><span class="mi">2</span><span class="p">)</span><span class="n">r</span> <span class="c1">#=> (17/2)</span>
</code></pre> Ruby master - Feature #10331 (Open): String#to_r to recognize negative denominatorshttps://bugs.ruby-lang.org/issues/103312014-10-06T14:44:18Zsawa (Tsuyoshi Sawada)
<p>Current behavior or <code>String#to_r</code> does not recognize negative denominators. This can lead to confusing results:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"1/-3"</span><span class="p">.</span><span class="nf">to_r</span>
<span class="c1">#=> (1/1)</span>
</code></pre>
<p>I propose negative denominators to be recognized.</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="s2">"1/-3"</span><span class="p">.</span><span class="nf">to_r</span>
<span class="c1">#=> (-1/3)</span>
</code></pre> Ruby master - Bug #10260 (Third Party's Issue): Cannot install "thin" gemhttps://bugs.ruby-lang.org/issues/102602014-09-18T18:39:19Zsawa (Tsuyoshi Sawada)
<p>When I try to install "thin" gem, I get the following error:</p>
<pre><code>$ sudo gem install thin
Building native extensions. This could take a while...
ERROR: Error installing thin:
ERROR: Failed to build gem native extension.
/usr/local/bin/ruby -r ./siteconf20140919-24244-x0j5an.rb extconf.rb
checking for rb_trap_immediate in ruby.h,rubysig.h... no
checking for rb_thread_blocking_region()... no
checking for inotify_init() in sys/inotify.h... yes
checking for writev() in sys/uio.h... yes
checking for rb_wait_for_single_fd()... yes
checking for rb_enable_interrupt()... no
checking for rb_time_new()... yes
checking for sys/event.h... no
checking for epoll_create() in sys/epoll.h... yes
creating Makefile
make "DESTDIR=" clean
make "DESTDIR="
compiling binder.cpp
compiling kb.cpp
compiling ssl.cpp
compiling rubymain.cpp
compiling ed.cpp
compiling cmain.cpp
compiling pipe.cpp
compiling em.cpp
em.cpp: In member function ‘void EventMachine_t::_RunEpollOnce()’:
em.cpp:574:37: error: ‘rb_thread_select’ was not declared in this scope
EmSelect (0, NULL, NULL, NULL, &tv);
^
em.cpp: In member function ‘int SelectData_t::_Select()’:
em.cpp:827:67: error: ‘rb_thread_select’ was not declared in this scope
return EmSelect (maxsocket+1, &fdreads, &fdwrites, &fderrors, &tv);
^
em.cpp: In member function ‘void EventMachine_t::_RunSelectOnce()’:
em.cpp:946:40: error: ‘rb_thread_select’ was not declared in this scope
EmSelect (0, NULL, NULL, NULL, &tv);
^
make: *** [em.o] Error 1
make failed, exit code 2
Gem files will remain installed in /usr/local/lib/ruby/gems/2.2.0/gems/eventmachine-1.0.3 for inspection.
Results logged to /usr/local/lib/ruby/gems/2.2.0/extensions/x86_64-linux/2.2.0-static/eventmachine-1.0.3/gem_make.out
</code></pre>
<p>I didn't have this problem with previous version of Ruby.</p> Ruby master - Bug #10184 (Closed): irb terminates with no method errorhttps://bugs.ruby-lang.org/issues/101842014-08-29T16:33:54Zsawa (Tsuyoshi Sawada)
<p>When I input the following lines in irb, the irb terminates.</p>
<pre><code>$ irb
irb(main):001:0> def !; end
=> :!
irb(main):002:0> !
/usr/local/lib/ruby/2.1.0/irb/input-method.rb:153:in `gets': private method `!' called for false:FalseClass (NoMethodError)
...
$
</code></pre>
<p>A corresponding question is posted on StackOverflow at <a href="http://stackoverflow.com/questions/25572126/irb-terminates-with-no-method-error/25572313#25572313" class="external">http://stackoverflow.com/questions/25572126/irb-terminates-with-no-method-error/25572313#25572313</a>.</p> Ruby master - Feature #10183 (Open): An alternative name for method `class`https://bugs.ruby-lang.org/issues/101832014-08-29T12:52:13Zsawa (Tsuyoshi Sawada)
<p>The method <code>class</code> is special in that it always has to have an explicit receiver in order to avoid crash with the keyword <code>class</code>. But this is very inconvenient. I have seen so many</p>
<pre><code>self.class
</code></pre>
<p>in codes. I propose that there should be an alternative name for this method so that it can be used with an implicit receiver, and the method name <code>class</code> should be gradually depricated.</p>
<p>As for the name, I have no clear idea. I can only think of <code>klass</code>, but perhaps someone else might come up with a better name.</p> Ruby master - Bug #10049 (Closed): RDoc bug for time formathttps://bugs.ruby-lang.org/issues/100492014-07-16T20:26:06Zsawa (Tsuyoshi Sawada)
<p>A bug report <a href="https://bugs.ruby-lang.org/issues/8941" class="external">https://bugs.ruby-lang.org/issues/8941</a> notes a contradiction between RDoc and Ruby behavior. If tadayoshi funaba is correct and <code>%Y</code> should be able to accept digits less than four, then the following RDoc description is a bug, and should be corrected.</p>
<pre><code>%Y - Year with century (can be negative, 4 digits at least)
</code></pre> Ruby master - Bug #9900 (Closed): Segmentation fault with recursive reference of a hashhttps://bugs.ruby-lang.org/issues/99002014-06-04T04:10:47Zsawa (Tsuyoshi Sawada)
<p>The following code raises a segmentation fault.</p>
<pre><code>Hash.new{|h,k| h[k]}[:foo]
# => [BUG] Segmentation fault at 0x007fff5f3fff80
</code></pre>
<p>This bug was found on stackoverflow <a href="http://stackoverflow.com/questions/24028557/irb-crash-segmentation-bug-and-ruby-syntax-clarification" class="external">http://stackoverflow.com/questions/24028557/irb-crash-segmentation-bug-and-ruby-syntax-clarification</a></p> Ruby master - Bug #9883 (Closed): Different behaviour between `==` and hash key lookup regarding ...https://bugs.ruby-lang.org/issues/98832014-05-30T04:06:14Zsawa (Tsuyoshi Sawada)
<p>This question is reported in stackoverflow (<a href="http://stackoverflow.com/questions/23946127" class="external">http://stackoverflow.com/questions/23946127</a>). When a multibyte character is split by <code>slice</code>, <code>==</code> ignores the split fragment of the character, while key lookup on hash does not:</p>
<pre><code class="ruby syntaxhl" data-language="ruby"><span class="n">s1</span> <span class="o">=</span> <span class="s2">"’xxxxxxxxxxxxxxxxxxxxxxxx"</span><span class="p">.</span><span class="nf">slice</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">24</span><span class="p">)</span>
<span class="n">s2</span> <span class="o">=</span> <span class="s2">"xxxxxxxxxxxxxxxxxxxxxxxx"</span>
<span class="n">s1</span> <span class="o">==</span> <span class="n">s2</span> <span class="c1"># => true</span>
<span class="p">{</span><span class="n">s2</span><span class="o">=></span><span class="s2">""</span><span class="p">}.</span><span class="nf">key?</span><span class="p">(</span><span class="n">s1</span><span class="p">)</span> <span class="c1"># => false</span>
</code></pre>
<p>This is inconsistent, and I believe either of the above two is a bug. If it is not a bug, but intended, then it is misleading, and I propose the feature should be changed.</p> Ruby master - Bug #9873 (Closed): YAML conversion of empty symbolhttps://bugs.ruby-lang.org/issues/98732014-05-28T15:26:59Zsawa (Tsuyoshi Sawada)
<p>The yaml gem changes the empty symbol into a string of a colon:</p>
<pre><code>require "yaml"
:"".to_yaml # => "--- ! ':'\n"
</code></pre>
<p>So, the following round trip fails to maintain the original:</p>
<pre><code>YAML.load(:"".to_yaml) # => ":"
</code></pre> Ruby master - Feature #9768 (Assigned): Method that is visible only within a certain module/classhttps://bugs.ruby-lang.org/issues/97682014-04-22T09:57:35Zsawa (Tsuyoshi Sawada)
<p>Some frameworks/libraries monkeypatch their own methods on Ruby core classes like <code>String</code>, <code>Hash</code>, <code>Array</code>, etc., and that is often causing problems/concerns of name conflict.</p>
<p>Seeing that these custom methods are used only in the context of a certain module/class, I request for a way to define a method (<code>foo</code>) on a module/class (<code>A</code>) so that it will be visible only from within a specified module/class (<code>B</code>) or its descendants. The following illustrates this situation:</p>
<pre><code>A.new.foo # => undefined
class B
A.new.foo # => defined
def bar
A.new.foo # => defined
end
def self.baz
A.new.foo # => defined
end
end
class C < B
A.new.foo # => defined
def bar
A.new.foo # => defined
end
def self.baz
A.new.foo # => defined
end
end
</code></pre>
<p>I do not have a certain syntax for this in mind, but I think it can be made much simpler, compared to the complicated syntax of refinement.</p>
<p>This is reminiscent of refinement, but they are pretty much different.</p>
<p>Refinement's purpose is to let certain methods be accessible from only a certain file. A typical use case would be a library developer defining their methods to be used from within the library and making such methods inaccessible from the end user.</p>
<p>On the other hand, the idea I am proposing here is for making method accessible from any file, but only within a certain module/class. A typical use case would be defining a method to be used by an end user, but only from within a context of certain module/class.</p> Ruby master - Bug #9728 (Closed): Regexp bughttps://bugs.ruby-lang.org/issues/97282014-04-11T06:41:13Zsawa (Tsuyoshi Sawada)
<p>As reported in StackOverflow (<a href="http://stackoverflow.com/questions/23004527" class="external">http://stackoverflow.com/questions/23004527</a>) (with a wrong expectation), the following regex pattern with the <code>*</code> operator does not match.</p>
<pre><code>"ab" =~ /(?!^a).*b/
# => nil
</code></pre>
<p>When <code>?</code> is used instead, it seems to match correctly:</p>
<pre><code>"ab" =~ /(?!^a).?b/
# => 1
</code></pre>
<p>According to the original reporter of the linked site, this does not happen in Ruby 1.9.3.</p> Ruby master - Bug #9701 (Closed): RDoc description for `String#<<` and `String#concat`https://bugs.ruby-lang.org/issues/97012014-04-04T04:52:41Zsawa (Tsuyoshi Sawada)
<p>As far as I can see, <code>String#<<</code> is an alias of <code>String#concat</code>, but in the RDoc, there is no mentioning of the connection between them. <code>String#<<</code> should be simply described as an alias of <code>String#concat</code>.</p> Ruby master - Feature #9667 (Open): Optimization of __FILE__ and __dir__https://bugs.ruby-lang.org/issues/96672014-03-24T09:19:04Zsawa (Tsuyoshi Sawada)
<p>In the same spirit as the string literal followed by <code>freeze</code> is optimized, I think <code>__FILE__</code> and <code>__dir__</code> should be optimized. Currently, they return different object id each time they are called.</p>
<pre><code>__FILE__.object_id # => 70183725179420
__FILE__.object_id # => 70183725129020
...
</code></pre>
<p>I propose them to be optimized so that they are only created once per occurrence.</p>
<pre><code>__FILE__.object_id # => 70183725179420
__FILE__.object_id # => 70183725179420
...
</code></pre> Ruby master - Bug #9581 (Closed): `=~` defined on a subclass of `String` is sometimes ignored, an...https://bugs.ruby-lang.org/issues/95812014-02-28T21:21:32Zsawa (Tsuyoshi Sawada)
<p>As is reported on StackOverflow (<a href="http://stackoverflow.com/questions/22103018" class="external">http://stackoverflow.com/questions/22103018</a>) by Gabriel, overridden <code>=~</code> on a subclass of <code>String</code> is sometimes ignored, and the original <code>String#=~</code> is called. Particularly, when we have:</p>
<pre><code>class MyString < String
def =~ re; :foo end
end
s = MyString.new("abc")
</code></pre>
<p>these give the correct result:</p>
<pre><code>r = /abc/; s =~ r # => :foo
s.send(:=~, r) # => :foo
s.send(:=~, /abc/) # => :foo
</code></pre>
<p>but in this case, <code>MyString#=~</code> is ignored, and <code>String#=~</code> is called instead:</p>
<pre><code>s =~ /abc/ # => 0
</code></pre> Ruby master - Feature #9557 (Open): Enumerator#next and Enumerator#peek with argumenthttps://bugs.ruby-lang.org/issues/95572014-02-23T09:14:18Zsawa (Tsuyoshi Sawada)
<p>It often happens that I want to move the current index of an enumerator by some arbitrary number <code>n</code>. <code>Enumerator#feed</code> takes the element as the argument, but that cannot be used if the enumerator has duplicate elements, or when I do not have information of a particular element to choose but just want to increment the index by some number. <code>Enumerator#next</code>, on the other hand, has a fixed value <code>1</code> to be incremented. It would be convenient if <code>Enumerator#next</code> takes an optional argument that represents the difference of the index to be incremented. The argument can be understood to be defaulted to <code>1</code> when absent.</p>
<p>Also, I often want to look not necessarily the current position, but some position away. It would be good if <code>Enumerator#peek</code> takes an optional argument that represents the positional difference to be peeked. The argument can be understood to be defaulted to <code>0</code> when absent.</p>
<pre><code>enum = [0, 1, 2, 3, 4, 5, 6, 7, 8].to_enum
enum.peek # => 0
enum.peek(0) # => 0
enum.peek(1) # => 1
enum.peek # => 0
enum.next # => 0
enum.next(1) # => 1
enum.next(2) # => 2
enum.peek # => 4
enum.peek(0) # => 4
enum.peek(1) # => 5
enum.peek # => 4
enum.next # => 4
enum.next(1) # => 5
enum.next(2) # => 6
peek # => 8
</code></pre> Ruby master - Feature #9515 (Open): `IO.each` and `CSV.each`https://bugs.ruby-lang.org/issues/95152014-02-12T16:16:41Zsawa (Tsuyoshi Sawada)
<p>In <code>IO</code> class, there are pairs of a class method and an instance method with related function:</p>
<ul>
<li>
<code>IO.read</code> and <code>IO#read</code>
</li>
<li>
<code>IO.write</code> and <code>IO#write</code>
</li>
<li>
<code>IO.foreach</code> and <code>IO#each</code> (or its alias <code>IO#each_line</code>)</li>
</ul>
<p>For consistency, please make <code>IO.each</code> an alias for <code>IO.foreach</code>.</p>
<p>The same thing can be said for <code>CSV.each</code>.</p> Ruby master - Bug #9295 (Closed): `Exception#backtrace_locations` returns `nil`https://bugs.ruby-lang.org/issues/92952013-12-25T04:32:13Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
If I raise an <code>ArgumentError</code> by calling a method with wrong number of arguments, <code>Exception#backtrace_locations</code> returns <code>nil</code>, which I think is a bug:</p>
<pre><code>def foo; end
begin
foo(:bar)
rescue => e
p e.backtrace_locations
end
# => nil
</code></pre>
<p>If, instead, I raise an error manually, then it returns an array as expected:</p>
<pre><code>begin
raise ArgumentError.new
rescue => e
p e.backtrace_locations
end
# => ["this_file:2:in `<main>'"]
</code></pre>
<p>=end</p> Ruby master - Feature #9111 (Open): Encoding-free String comparisonhttps://bugs.ruby-lang.org/issues/91112013-11-14T22:15:06Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
Currently, strings with the same content but with different encodings count as different strings. This causes strange behaviour as below (noted in StackOverflow question <a href="http://stackoverflow.com/questions/19977788/strange-behavior-in-packed-ruby-strings#19978206" class="external">http://stackoverflow.com/questions/19977788/strange-behavior-in-packed-ruby-strings#19978206</a>):</p>
<pre><code>[128].pack("C") # => "\x80"
[128].pack("C") == "\x80" # => false
</code></pre>
<p>Since <code>[128].pack("C")</code> has the encoding ASCII-8BIT and <code>"\x80"</code> (by default) has the encoding UTF-8, the two strings are not equal.</p>
<p>Also, comparison of strings with different encodings may end up with a messy, unintended result.</p>
<p>I suggest that the comparison <code>String#<=></code> should not be based on the respective encoding of the strings, but all the strings should be internally converted to UTF-8 for the purpose of comparison.</p>
<p>=end</p> Ruby master - Bug #9077 (Closed): RDoc typographical errorhttps://bugs.ruby-lang.org/issues/90772013-11-05T02:50:05Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
There is a typographical error in <a href="http://www.ruby-doc.org/core-2.0.0/_lib/racc/rdoc/grammar_en_rdoc.html#label-Operator+Precedance" class="external">http://www.ruby-doc.org/core-2.0.0/_lib/racc/rdoc/grammar_en_rdoc.html#label-Operator+Precedance</a>.</p>
<pre><code>Operator Precedance => Operator Precedence
</code></pre>
<p>=end</p> Ruby master - Feature #8970 (Open): Array.zip and Array.producthttps://bugs.ruby-lang.org/issues/89702013-10-01T03:57:09Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
Most of the time when I use <code>Array#zip</code> or <code>Array#product</code>, I feel cumbursome that I have to take out the first array and pass it as a receiver. For example, if I have</p>
<pre><code>a = [[:a, :b, :c], [:d, :e, :f], [:g, :h, :i]]
</code></pre>
<p>I have to do something like this:</p>
<pre><code>a.first.zip(*a.drop(1)){...}
a.first.product(*a.drop(1)){...}
</code></pre>
<p>Sometimes, the receiver (i.e., the first array) has significance, but most other times, that breaks asymmetry, making the code look ugly.</p>
<p>I would be happy if we had <code>Array.zip</code> and <code>Array.product</code> in addition so that we can do it like this:</p>
<pre><code>Array.zip(*a){...}
Array.product(*a){...}
</code></pre>
<p>=end</p> Ruby master - Feature #8948 (Assigned): Frozen regexhttps://bugs.ruby-lang.org/issues/89482013-09-25T04:02:37Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
I see that frozen string was accepted for Ruby 2.1, and frozen array and hash are proposed in <a href="https://bugs.ruby-lang.org/issues/8909" class="external">https://bugs.ruby-lang.org/issues/8909</a>. I feel there is even more use case for a frozen regex, i.e., a regex literal that generates a regex only once. It is frequent to have a regex within a frequently repeated portion of code, and generating the same regex each time is a waste of resource. At the moment, we can have a code like:</p>
<pre><code>class Foo
RE1 = /pattern1/
RE2 = /pattern1/
RE3 = /pattern1/
def classify
case self
when RE1 then 1
when RE2 then 2
when RE3 then 3
else 4
end
end
end
</code></pre>
<p>but suppose we have a frozen <code>Regexp</code> literal <code>//f</code>. Then we can write like:</p>
<pre><code>class Foo
def classify
case self
when /pattern1/f then 1
when /pattern1/f then 2
when /pattern1/f then 3
else 4
end
end
end
</code></pre>
<p>=end</p> Ruby master - Bug #8885 (Rejected): Incorrect time is created for time including leap secondshttps://bugs.ruby-lang.org/issues/88852013-09-10T16:13:11Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
<code>Time.new</code> creates incorrect time when the time includes a leap second.</p>
<pre><code>Time.new(2012, 6, 30, 23, 59, 60)
# => 2012-07-01 00:00:00 +0900 # Wrong. Should be 2012-06-30 23:59:60 +0900
Time.new(2012, 6, 30, 23, 59, 60) == Time.new(2012, 7, 1, 0, 0, 0)
# => true # Wrong. Should be `false`.
</code></pre>
<p>=end</p> Ruby master - Feature #8834 (Open): Kernel#load_relativehttps://bugs.ruby-lang.org/issues/88342013-08-30T10:32:44Zsawa (Tsuyoshi Sawada)
<p>The intended difference between <code>Kernel#require</code> and <code>Kernel#load</code> is that the former is for external libraries and the latter is for Ruby scripts internal to the project. Considering this fact, <code>load</code> should be more likely than <code>require</code> to be used in a situation where you want to call a file through a relative path. Strangely, there is <code>Kernel#require_relative</code>, but no <code>Kernel#load_relative</code>. I request <code>Kernel#load_relative</code>. It is even more necessary than <code>Kernel#require_relative</code>.</p>
<p>It seems to me that people are using <code>Kernel#require_relative</code> when they want to use a relative path, even in the context where they are supposed to use <code>load</code> because of the lack of <code>Kernel#load_relative</code>. I don't think this is a good practice. Furthermore, in cases where you have a file without a <code>.rb</code> or other extention that you want to call via a relative path, there is no good way to do it.</p> Ruby master - Bug #8766 (Closed): RDoc documentation bug: Symbol literalhttps://bugs.ruby-lang.org/issues/87662013-08-10T23:04:22Zsawa (Tsuyoshi Sawada)
<p>RDoc page <a href="http://www.ruby-doc.org/core-2.0/doc/syntax/literals_rdoc.html#label-Symbols" class="external">http://www.ruby-doc.org/core-2.0/doc/syntax/literals_rdoc.html#label-Symbols</a> has a description and an example:</p>
<pre><code>Like strings, a single-quote may be used to disable interpolation:
:"my_symbol#{1 + 1}" #=> :"my_symbol\#{1 + 1}"
</code></pre>
<p>Whereas the text mentions single quote, the example has double quotes.</p> Ruby master - Feature #8614 (Open): Object#singleton_class with a blockhttps://bugs.ruby-lang.org/issues/86142013-07-10T01:04:42Zsawa (Tsuyoshi Sawada)
<p>=begin<br>
Most of the time when I use <code>Object#singleton_class</code>, I use it with <code>class_eval</code> following it, like follows:</p>
<pre><code>class Foo
singleton_class.class_eval{attr_accessor :bar}
end
</code></pre>
<p>I think it would be convenient if <code>Object#singleton_class</code> can optionally take a block so that the following will mean the same as above.</p>
<pre><code>class Foo
singleton_class{attr_accessor :bar}
end
</code></pre>
<p>=end</p> Ruby master - Bug #8607 (Closed): Stack consistency error (sp: 16, bp: 17)https://bugs.ruby-lang.org/issues/86072013-07-08T00:01:32Zsawa (Tsuyoshi Sawada)
<p>The following code:</p>
<pre><code>class A
attr_accessor :foo
end
class B
def initialize(parent)
@parent = parent
end
def method_missing(method, *args, &block)
@parent.send(method)
end
end
B.new(A.new).foo = :bar
</code></pre>
<p>returns:</p>
<pre><code>[BUG] Stack consistency error (sp: 16, bp: 17)
</code></pre>
<p>It has been reported on Stackoverflow (<a href="http://stackoverflow.com/questions/17513074/ruby-2-0-throws-bug-stack-consistency-error" class="external">http://stackoverflow.com/questions/17513074/ruby-2-0-throws-bug-stack-consistency-error</a>) by NicoSantangelo.</p> Ruby master - Bug #7803 (Closed): RDoc documentation: `Array#&` clarificationhttps://bugs.ruby-lang.org/issues/78032013-02-08T15:38:57Zsawa (Tsuyoshi Sawada)
<p>In the RDoc documentation for <code>Array#&</code>, it does not mention whether the order of the elements in the returned array preserves the order in the receiver. There is a question raised regarding this point in stackoverflow:</p>
<pre><code>http://stackoverflow.com/questions/14764135/is-order-preserved-in-arrays-when-intersection-is-done
</code></pre>
<p>and it mentions that that is included in the test for RubySpec</p>
<pre><code>https://github.com/rubyspec/rubyspec/blob/master/core/array/intersection_spec.rb#L16
</code></pre>
<p>so it looks like that is taken for granted, but it is not guaranteed. If it is indeed a feature, then that should be written in the document. If not, (meaning the order might not be preserved in a future implementation), then that should also be mentioned in the document as a warning. The documentation for <code>Array#-</code> makes that point clear:</p>
<pre><code>Array Difference---Returns a new array that is a copy of the original array, removing any items that ...
</code></pre>
<p>so, perhaps the docmentation for <code>Array#&</code> should be written along the same line.</p> Ruby master - Bug #7571 (Closed): RDoc documentation bug in Regexp#===https://bugs.ruby-lang.org/issues/75712012-12-16T10:55:54Zsawa (Tsuyoshi Sawada)
<p>RDoc documentation for `Regexp#===' says:</p>
<pre><code>Case Equality—Synonym for Regexp#=~ used in case statements.
</code></pre>
<p>but it is not a synonym for <code>Regexp#=~' as </code>Regexp#===' returns <code>true' or </code>false' and <code>Regexp#=~' return an integer or </code>nil`.</p> Ruby master - Bug #7190 (Closed): warning: already initialized constant の書式https://bugs.ruby-lang.org/issues/71902012-10-20T11:00:58Zsawa (Tsuyoshi Sawada)
<p>未定義の定数を参照した場合のエラーメッセージでは名前空間がすべて表示されます:</p>
<pre><code>module A; B; end
#=> NameError: uninitialized constant A::B
A::B
#=> NameError: uninitialized constant A::B
</code></pre>
<p>しかし、既に定義してある定数を再定義した場合の警告メッセージでは名前空間が表示されません:</p>
<pre><code>module A; B = :foo end
module A; B = :bar end
#=> warning: already initialized constant B
A::B = :baz
#=> warning: already initialized constant B
</code></pre>
<p>後者の場合も前者の場合にならって名前空間を表示した方がよいと思います。</p>
<pre><code>warning: already initialized constant A::B
</code></pre>
<p>メタプログラミングで、$stderr = StringIO.new のように警告メッセージをリダイレクトしてコード内で定数の再定義を捕捉したい場合に、名前空間なしでは問題になっている定数を再現できません。</p> Ruby master - Bug #4781 (Closed): Engrish in comment in Regexp#=~https://bugs.ruby-lang.org/issues/47812011-05-26T01:02:09Zsawa (Tsuyoshi Sawada)
<p>I see the following grammatical mistakes in ruby-doc, probably reflecting the comments in the source:</p>
<p>Regexp#=~</p>
<p>wrong: The assignment is not occur if the regexp is not a literal.<br>
correct: The assignment does not occur if the regexp is not a literal.</p>
<p>wrong: The assignment is not occur if the regexp is placed at right hand side.<br>
correct: The assignment does not occur if the regexp is placed at the right hand side.</p>