From: Robert Dober <robert.dober@...>
Date: 2009-06-17T08:43:19+09:00
Subject: Re: each by arity

On Tue, Jun 16, 2009 at 12:33 PM, trans<transfire@gmail.com> wrote:
>
>
> On Jun 16, 2:10 am, Robert Klemme <shortcut...@googlemail.com> wrote:
>
>> Question is whether it is clever to duplicate all methods with another
>> one that has "_slice" appended to the name.  I personally favor the
>> approach with Enumerator, e.g. depending on version
>
> Not clever... facetious. Of course Enumerator is useful, and with 1.9
> fairly elegant. But rather, the question is why we must do
>
>  enum.each_slice(2).map {|a,b| ...}
>
> when
>
>  enum.map {|a,b| ...}
>
> could be made to work. This is especially interesting b/c it seems the
> underlying implementation stands to be simpler and faster by doing so.
That is intriguing and I am surprised.

However, why should

  enum.map{ |a,b| }
have the semantics of
  enum.each_slice( 2 )....
and not
   enum.each_cons( 2 ).... ?

Maybe we need to push the abstraction even higher. Hopefully you
understand what that sentence means, because I do not, but it felt
just right to write it. Strange, strange.

Now I am not so fond of enumerator, because it is really crazy.

  x=%w{a b c d}
  y = x.enum_for( :rand )
  y.each do | a | p a end
=> 0.680141319345242

Do you agree with me that enum_for should use #public_send instead of #send?

Cheers
Robert

Cheers
Robert
>
> T.
>
>
>



-- 
Toutes les grandes personnes ont d’abord été des enfants, mais peu
d’entre elles s’en souviennent.

All adults have been children first, but not many remember.

[Antoine de Saint-Exupéry]