From: Alex Young <alex@...>
Date: 2012-07-04T17:36:09+09:00
Subject: [ruby-core:46170] Re: [ruby-trunk - Feature #6693][Open] Don't warn for unused variables starting with _

On 04/07/12 05:01, marcandre (Marc-Andre Lafortune) wrote:
>
> Issue #6693 has been reported by marcandre (Marc-Andre Lafortune).


I don't know about anyone else, but I'm already using _foo as a pattern 
for private-like markers.  I think I picked it up from Python.

What I mean when I say "private-like" is "you can see this but shouldn't 
have to touch it", or "I need a visible identifier here which won't 
collide with your code".  It often crops up with delegates or proxies 
where I need to obviously separate out the methods on the intermediary 
from the methods on the target.  For example:

   class VCR

     attr_reader :_calls

     def initialize( delegate )
       @delegate = delegate
       @_calls = []
     end

     def method_missing(sym, *args, &blk )
       @_calls << [sym, args, blk]
       @delegate.__send__( sym, *args, &blk )
     end

   end

Here I don't want the #_calls method to be likely to collide with 
anything on @delegate, so I'm using a _ as a sort of 
method_missing-escaping namespace.  While this isn't specific to local 
variables, it would be extremely confusing to have identical-looking 
conventions for local variables and methods meaning completely different 
things.

Does anyone else do this, or is it just me?

-- 
Alex

>
> ----------------------------------------
> Feature #6693: Don't warn for unused variables starting with _
> https://bugs.ruby-lang.org/issues/6693
>
> Author: marcandre (Marc-Andre Lafortune)
> Status: Open
> Priority: Low
> Assignee:
> Category: core
> Target version: 2.0.0
>
>
> Currently, variables which are set but not used will generate a warning (ruby -w), except if they have the special name "_".
>
> So best practice is to use "_" for all unused variables. This does not encourage readable code.
>
>      # Currently must read:
>      _, _, _, suffix = parse_name
>
>      # could read:
>      _first, _middle, _last, suffix = parse_name
>
> We should not warn for unused variables starting with a "_".
>
> This would create an option (but no obligation) to use more descriptive names than "_" without generating warnings.
>
>
>