From: Charles Oliver Nutter <headius@...>
Date: 2010-09-10T00:37:45+09:00
Subject: [ruby-core:32235] Re: Ruby 2.0 Wiki/Wish-list?

On Wed, Sep 8, 2010 at 3:06 PM, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
> |Module#prepend (but there is a ticket for that, if I remember correctly):
>
> I am positive about prepending a module. ��It will be addressed on Ruby
> 2.0 in whatever form.

I'd like to be part of design and implementation discussions on this,
if possible. I've prototyped it previously, but never committed that
work anywhere. I believe it will be implemented mostly like the
current "include wrapper" for modules, but positioned and dealt with a
bit differently.

> |And the other one is proper module propagation:
> |
> | �� �� �� module Extension
> | �� �� �� �� �� �� �� def foo
> | �� �� �� �� �� �� �� �� �� �� �� 42
> | �� �� �� �� �� �� �� end
> | �� �� �� end
> |
> | �� �� �� Enumerable.send(:include, Extension)
> | �� �� �� Array.new.foo # => 42
> |
> |The latter being not yet the case is rather confusing and not correctly fixable from within Ruby.
>
> This one is quite difficult to solve without huge cost. ��If we add
> subclass / submodule reference as JRuby does, this one can be solved
> but I hesitate to add costly weak references.

In JRuby, there are as many weak references as there are subclasses
(including module wrappers) and inclusions of modules (modules keep a
list of all inclusion points). After booting RubyGems, the total
number of such elements is in the 1200-1300 range. Rails and other
frameworks would obviously bump this number up a lot. It's not clear
what impact it has on the JVM, though it's safe to say that it's not
free and that it's probably cheaper than on MRI.

- Charlie