From: Raf Coremans <rrafje@...>
Date: 2007-05-13T02:56:53+09:00
Subject: Re: copy methods from one module to another, with a twist

2007/5/11, David Chelimsky <dchelimsky@gmail.com>:
> Hi all. I'm trying to figure out how to copy methods from one module
> to another (actually subclasses of Module because I don't want to
> actually extend Module in this context) and I could use some help.
>
> The following works fine.
>
> irb(main):001:0> class Mod < Module; end
> => nil
> irb(main):002:0> mod1 = Mod.new
> => #<Mod:0x6108>
> irb(main):003:0> mod2 = Mod.new
> => #<Mod:0x89198>
> irb(main):004:0> mod1.send :define_method, :mod1_method do
> irb(main):005:1* "I'm defined in mod1"
> irb(main):006:1> end
> => #<Proc:0x0007d780@(irb):4>
> irb(main):007:0> class Thing; end
> => nil
> irb(main):008:0> Thing.send :include, mod1
> => Thing
> irb(main):009:0> t = Thing.new
> => #<Thing:0x67034>
> irb(main):010:0> t.mod1_method
> => "I'm defined in mod1"
>
> What I have to do, however, is more complex. I need to copy
> #mod1_method to mod2, and I only have access to the two modules when I
> want to do this (not the classes/objects that include them). So,
> adding to the above ...
>
> irb(main):011:0> class Other; end
> => nil
> irb(main):012:0> Other.send :include, mod2
> => Other
> irb(main):013:0> o = Other.new
> => #<Other:0x57ad0>
>
> I want to get from here to the following:
>
> o.mod1_method
>
> I've tried these approaches:
>
> mod2.send :include, :mod1
> mod2.send :extend, :mod1
>
> What's the right way to do this?
>
> Thanks,
> David
>

Erm, actually forget my previous reply, it's all much simpler: simply
include module Mod1 in module Mod2 before including module Mod2 in
class Other:

module Mod1
  def mod1_method
    "I'm defined in Mod1"
  end
end

module Mod2
  include Mod1
end

class Thing
  include Mod1
end

class Other
  include Mod2
end

p Thing.new.mod1_method # => "I'm defined in Mod1"
p Other.new.mod1_method # => "I'm defined in Mod1"

Remark that there is no need to subclass Module in fact, because
you're not at all extending class Module.


Regards,
Raf