From: "Randy W. Sims" <ml-ruby@...>
Date: 2004-09-20T22:52:40+09:00
Subject: Re: Array#index block and rdetect

David A. Black wrote:
> Hi --
> 
> On Mon, 20 Sep 2004, Yukihiro Matsumoto wrote:
> 
>>  * How about other enumerable classes?
> 
> 
> I think the idea of every enumerable class having an "index", defined
> as part of that class, is possibly useful.  For hashes it could be the
> keys; for arrays, the integer index; for files, the line number.  In
> some cases (like index/key for hashes), it might be redundant.  But it
> might open up some good possibilities.  
> 
> That would mean an enumerable class would have to be able to say:
> "This is how I define 'index'."  I'm not sure how that would work.  

All enumerable objects don't neccessarilly have a meaningful concept of 
an index. Eg. sets, multisets. Enumerable and Indexable are two 
different things, though Indexable extends Enumerable.