From: Matthias Veit <matthias_veit@...>
Date: 2002-07-16T07:29:28+09:00
Subject: Re: cut & paste for code


>>>> HEF == "Hal E. Fulton" <hal9000@hypermetrics.com> wrote:

HEF> Move the methods into a module M.
HEF> Include M in both A and B.
HEF> 
HEF> No duplication of code that way, and
HEF> no inheritance.
HEF> 
HEF> How is that?
HEF> 
HEF> There is probably an esoteric solution that 
HEF> will literally do exactly what you wanted...
HEF> but I can't think of a way to do it yet.

I really like this solution, but I think my problem 
is even more esoteric. Following situation:

-------------------------------------------
module R
  class A
  end
  class B
    def a
      return A.new
    end
  end
end

module T
  class A
    copy_from(R::A) #magic copy
  end
  class B
    copy_from(R::B) #magic copy
  end
end
--------------------------------------------

What i want to achieve is described best with "copy inheritance"
- no real inheritance, more like copy the source code from one
class to another (as easy as in every editor).
The call T::B.new.a shall return a T::A not an R::A.


With the module approach it looks like:
--------------------------------------------
module R
  class A
  end

  module B_
    def a
      return A.new
    new
  end

  class B
    include B_
  end
end

module T
  class A
  end

  class B
    include R::B_
  end
end
--------------------------------------------

Because the module B_ gets its binding in context of R, A.new
means R::A.new. Thus the include in T::B ought to do something 
like rebind after include.

Do you have any idea?
 
Best regards,
Matthias
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