Feature #14787

Show documents when completion

Added by aycabta (aycabta .) about 1 month ago. Updated about 1 month ago.

Target version:


The "irb/completion" provides completion for classes, modules, symbols, and methods. This patch provides a new feature for it that shows documents when press TAB key one more after exact matches. This uses RDoc as a library.


$ ruby -Ilib bin/irb 
irb(main):001:0> "".gsub # press TAB key twice
"".gsub   "".gsub!
irb(main):001:0> "".gsub # press TAB key one more
# show RI document and press q to quit
irb(main):001:0> "".gsub

I'm the RDoc maintainer. A lot of Ruby users tell me "I'm using Google for reading documents of Ruby".

RDoc installs all documents to Ruby's directory by default. Many users never use it because it's just for RI("ri" command). I think that it is a reason of that many users don't attach importance to documentation.

Perl has "perldoc" feature and users easily access documents of modules by "perldoc" command. Python has "docstring" feature and users can access it on REPL. Those are each language's design of importance. Users use the language on the documentation design, so library developers write documents on the documentation design. Ruby doesn't have documentation design like Perl and Python. Ruby just has RDoc, IRB, and any other supports, but these are just fragmented features, these are not a documentation design.

Ruby needs many new features of documentation. This is one of them. This new feature gives new development environment.

show_doc_when_completion.patch (8.9 KB) show_doc_when_completion.patch aycabta (aycabta .), 05/25/2018 07:43 PM


#1 [ruby-core:87262] Updated by shevegen (Robert A. Heiler) about 1 month ago

I am fine with the suggestion.

If possible, a configuration option for IRB would be nice for people
to decide on their own whether to use the above or not, but this is
a small detail, not really that important anyway.

However had, to the comment:

RDoc installs all documents to Ruby's directory by default. Many
users never use it because it's just for RI("ri" command). I think
that it is a reason of that many users don't attach importance
to documentation.

I remember many years ago, I was learning ruby through the old pickaxe,
which was very nice; it provided cohesive documentation in a book format.
I like books, they are a lot easier for me to read in a concentrated
manner than computer screens. Anyway, back on topic, I was never very
happy with ruby's online documentation. So not "just" rdoc but in general;
that was a very long time ago though. Documentation has improved a lot
but it's still not ... how shall I see it ... awesome.

Back then, a long time ago, I started to compile stuff on my own and store
them in my local knowledgebase, which is unfortunately a mix of german and
english. I usually prefer english since it is the language with more
"leverage" (more people know it), but my brain simply processes german text
faster/easier still.

I am, however had, also of the generation that can't deal with man-pages and
instead simply "googles for wisdom"; and also uses Stack Overflow. When
something seems useful, I integrate it into my local collection of useful
stuff to know. Often I also find useful information on blogs, including about

When I compile ruby from source, which I do (I compile almost everything from
source, using ruby for it of course; only the initial ruby-bootstrap may go
via a shell script, to have ruby running), I always disable all documentation.

So no ri, rdoc, capi etc... I don't want any of these on my computer. Because

a) I won't need them.
b) I don't use them.
c) In particular the rdoc-generation step takes quite a long time, so skipping
that makes compiling ruby faster; and sometimes bugs can happen where stuff
fails, during that stage, which is not acceptable to me if I can avoid it.

Having said that, I rely on documentation of other ruby projects or projects
in general; and I use markdown myself for gems I created and maintain. Markdown
is really neat; I autogenerate files based on a template which allows
for some macros (commonly used things I have to do for some of my gems).

I also do not use "ri" on the commandline. I would not know why, because I
myself simply do not use local look-up ways for documentation normally. I
really "just google". And using the browser is about 100x more convenient for me
as well.

The above is one use case. I am sure people have different means to use and
work with documentation in general. But I am also sure that quite many people
prefer browser-based documentation and tools at all times.

PS: Just before this is misunderstood, I agree with improving in-irb documentation
in this regards. I love introspection, including things such as show-source
in pry and so on.

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