From: "yhara (Yutaka HARA)" <redmine@...>
Date: 2012-10-25T19:38:45+09:00
Subject: [ruby-core:48257] [ruby-trunk - Feature #6641] Hash.auto constructor


Issue #6641 has been updated by yhara (Yutaka HARA).

Target version changed from 2.0.0 to next minor


----------------------------------------
Feature #6641: Hash.auto constructor
https://bugs.ruby-lang.org/issues/6641#change-31535

Author: trans (Thomas Sawyer)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: next minor


=begin
It is not uncommon to need a Hash following the pattern:

  Hash.new{ |h,k| h[k]={} }

Another common example:

  Hash.new{ |h,k| h[k]=[] }
  
This is common enough that it would very nice if we could have a more concise form, e.g.

  Hash.auto{ {} }

Or for the second example:

  Hash.auto{ [] }

Pure Ruby implementation is pretty simple:

  def Hash.auto
    Hash.new{ |h,k| h[k] = yield }
  end

I think it would be nice to have in Core.

This is secondary, but it just occurred to me. Could there even be a literal notation for the above? Something like:

  {}([])

?
=end



-- 
http://bugs.ruby-lang.org/