From: John Carter <john.carter@...>
Date: 2004-08-11T07:00:27+09:00
Subject: Re: FirstEachLast, an extension to the Enumerable module.

On Tue, 10 Aug 2004, Michael Neumann wrote:

> Why not something like this (each_with_first_last does not exist!):
>
>  blah.each_with_first_last {|element, pos|
>    case pos
>    when :inside # or middle
>      ...
>    when :first
>      ...
>    when :last
>      ...
>    end
>  }

I like the cleaner syntax.

> I know, you could also use each_with_index instead (this one exists!):
>
>  blah.each_with_index {|element, inx|
>    if inx == 0
>      # first
>    elsif inx < blah.size
>      # inside
>    else
>      # last
>    end
>  }
>
> But that might not work for all Enumerable's.

Nope, that is order N^2 for enumerables without a O(1) implementation of
size. Simply won't do for me.

> Or maybe, an extended each_with_index2?:

Yip, could hack the .c code for each_with_index of enum.c

blah.first_each_last do |e,pos|
   case pos
   when :first
     ....
   when :inner
     ....
   when :last
     ......
   when :empty
     .....
   end
end


John Carter                             Phone : (64)(3) 358 6639
Tait Electronics                        Fax   : (64)(3) 359 4632
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