Bug #12758: Error when passing Hash construction to function

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-linux]
• Backport: 2.3: UNKNOWN

[purplefishies (Jimi Damon)]

I apologize if this is a known issue but I couldn't find it in the search.

If you have a function that can take a Hash, it behaves correctly if you pass a variable that contains the Hash compared to when you pass in a Hash construction using braces {}.

Example

def foo(a)
puts a.class
puts a
end

foo [1,2]
Array
[1, 2]
a = { a:1 }
foo a
Hash
{:a=>1}

This breaks

foo { a:1 }

SyntaxError: (irb):23: syntax error, unexpected ':', expecting '}'
foo {a:1}
^

but this works

foo( {a:1} )
Hash
{:a=>1}

This is more of a bug related to consistent syntax of the language and it is something that is allowed in Groovy and Scala

[wanabe (_ wanabe)]

This is in FAQ.
Please see http://ruby-doc.org/docs/ruby-doc-bundle/FAQ/FAQ.html#s6 : "6.7 Why can't I pass a hash literal to a method: p {}?"

And you can pass a hash to method without braces when it is last argument.

irb(main):001:0> p a: 1
{:a=>1}
=> {:a=>1}
irb(main):002:0> p 1 => 2
{1=>2}
=> {1=>2}
irb(main):003:0> p a: 1, 2
SyntaxError: (irb):3: syntax error, unexpected '\n', expecting =>
	from /usr/local/bin/irb:11:in `<main>'
irb(main):004:0>

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Rejected

Let me reject this (a FAQ).