From: Brian Candler <B.Candler@...>
Date: 2003-05-30T23:26:21+09:00
Subject: Re: Iteration - last detection

On Fri, May 30, 2003 at 10:09:39PM +0900, Carlos wrote:
> > I must be missing something; why is this not an incredibly simple thing to
> > achieve?
> > 
> > module Enumerable
> >   def each_with_last
> 
> The methods in Enumerable don't call #each_with_last, they call
> #each...  But now it seems that they don't call #each either :-/.

I don't follow. The pickaxe says:

   module Enumerable
   Relies on: each, <=>

   The Enumerable mixin provides collection classes with several
   traversal and searching methods, and with the ability to sort. The
   class must provide a method each, which yields successive members of
   the collection. 
   <snip>

So they only rely on the existence of 'each', unless you are using
sort/min/max.

I thought the question was "how do I get a method like 'each', but which
includes a flag saying whether this is the last element or not?" In which
case, you just define another method which does that, called (say)
'each_with_last', which makes use of 'each'. Where does this fail?

Cheers,

Brian.