From: 7rans <transfire@...>
Date: 2009-08-29T13:50:35+09:00
Subject: Re: #map, #select semantics



On Aug 28, 9:54 am, "David A. Black" <dbl...@rubypal.com> wrote:

> I guess I like the simplicity of defining each, including Enumerable,
> and getting pre-defined behavior. I know that Hash and Array already
> override a few things, though, so it's never been quite that simple.
> Still, given the underlying mechanism, there's no way to generalize
> returning a same-class object.

Sure there is --or at least it can be made complete predictable. Just
define a special class method, eg.

  class Array
    def self.enumerable_instance; []; end
   end

  class Hash
    def self.enumerable_instance; {}; end
   end

Then a uniform "add". Eg. #<< (btw I love Hash#<<) and the whole thing
can be generalized.

This has been discussed before, but for whatever reason the idea has
been disregarded. I suspect efficiency hacks have come to out way any
of these nice "uniformalizaions".

T.