From: Dave Thomas <dave@...>
Date: 2003-04-25T15:55:06+09:00
Subject: Re: Hashes and Enumerable#each_with_index

Yukihiro Matsumoto wrote:

>     * each_with_foo should be available for all built-in classes that
>       have obj[x] access.
> 
>     * each_with_foo must give (x,y) that obj[y] == x be true always.
> 
> Replace "foo" with the right word.  I don't think it's "key", since
> Array index is not key after all.

Or, have each class that wants to support this protocol define a method 
'each_foo'. Then have enumerable implement 'each_with_foo' as

   module Enumerable
     def each_with_foo
       each_foo {|foo| yield self[foo], foo}
     end
   end

Then the change to Hash is simply

   alias each_foo each_key

and to array

   alias each_foo each_index


However, how often to you want to do an each_with_index polymorphically?


Cheers


Dave