From: Rick DeNatale <rick.denatale@...>
Date: 2007-07-21T03:24:55+09:00
Subject: Re: Array : each_with_index

On 7/19/07, Marcel Molina Jr. <marcel@vernix.org> wrote:
> On Thu, Jul 19, 2007 at 03:46:10PM +0900, Vin Raja wrote:
> > I have following lines
> >
> > m=['a','b','c']
> > puts m.each_with_index{|v,i| i}
> >
> > which output in:
> >
> > >ruby try.rb
> > a
> > b
> > c
> > >Exit code: 0
>
> irb(main):003:0> m.each_with_index{|v,i| i}
> => ["a", "b", "c"]
> irb(main):004:0> m.each_with_index{|v,i| p i}
> 0
> 1
> 2
> => ["a", "b", "c"]
>
> The i variable in the block is indeed the index. But the result of the entire
> each_with_index expression is not the result of each block invocation, but the collection
> of all the array elements.
>
> marcel
> --
> Marcel Molina Jr. <marcel@vernix.org>

Actually Enumerable#each_with_index appears to return  the receiver
object itself, identity is preserved.

irb(main):001:0> a = %w{a word array}
=> ["a", "word", "array"]
irb(main):002:0> a.equal?(a.each_with_index {|e, i| [e, i]})
=> true
irb(main):003:0> a = (1..3)
=> 1..3
irb(main):004:0> a.equal?(a.each_with_index {|e, i| [e, i]})
=> true

Although this is not documented, and could of course be overridden in
a class which includes enumerable or one of its subclasses.
-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/