From: Yukihiro Matsumoto <matz@...>
Date: 2005-07-08T23:02:11+09:00
Subject: Re: accessing index inside map

Hi,

In message "Re: accessing index inside map"
    on Fri, 8 Jul 2005 19:20:48 +0900, "Robert Klemme" <bob.news@gmx.net> writes:

|> #$ ruby -renumerator -e 'p
|> #(1..6).enum_for(:each_with_index).map{|x,i|[2,5].include?(i) ?
|> #
|> #[2, 4, 3, 8, 10, 6]
|>
|> Hi Nobu,
|>
|> Wow, cool. But my brain is very tiny compared to other rubyist brains.
|>
|> i was hoping for something straight like,
|>
|>> [1,2,3,4,5,6].map{|x,i|[2,5].include?(i) ? x : x*2}
|> =>[2, 4, 3, 8, 10, 6]
|>
|> Maybe you can hack one for dumb rubyists like me.
|
|Err, are you kidding?  Enumerator isn't really that difficult - and you
|don't need to modify Hash or other classes.  It's a simple wrapper
|delegating each to each_with_index.  That simple.

We have vague plan to make enumerating method to return Enumerator
when no block is given in the future, so that

  require 'enumerator'
  (1..6).enum_for(:each_with_index).map{|x,i|[2,5].include?(i) ? x : x*2}

would be

  (1..6).each_with_index.map{|x,i|[2,5].include?(i) ? x : x*2}

then.  It's much simpler isn't it?

							matz.