From: Austin Ziegler <halostatue@...>
Date: 2005-07-28T21:09:49+09:00
Subject: Re: What's so special about operators, built-in classes and modules?

On 7/28/05, Devin Mullins <twifkak@comcast.net> wrote:
> >The problem I have with this sort of proposal is that since
> >classes keep state, if we allow the inclusion of Class objects, then
> >we have to start worrying about the inheritance of that state, just
> >like we do with normal Class inheritance.
> I don't understand that argument. In the context of being "include"d,
> Modules keep state, and suffer from no less than would Classes, if
> includable, as far as I can tell. What am I forgetting?

FYI, your quoting mechanism is off. IIRC, I wrote that, not James.
When a module is mixed into a class, its references to instance
variables are bound to the instance of the class.

  module Foo
    def baz
      @baz ||= 0
      @baz += 1
    end
  end

  class Bar
    include Foo
    def blat
      @blat ||= 0
      @blat += 1
    end
  end

  moof = Bar.new
  moof.instance_variables # => []
  moof.blat; moof.instance_variables # => ["@blat"]
  moof.baz; moof.instance_variables # => ["@blat", "@baz"]

If we include classes, then we have to start caring about the origin
of instance variables.

-austin
-- 
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca