From: Mark Hahn <mchahn@...>
Date: 2001-11-01T01:57:20+09:00
Subject: [ruby-talk:23984] Re: Overiding a method in another module

I implemented the following.  I think it matches your suggestion.  It didn't
work:

module M1
  class C1
    def m_1
      p '1'
    end
  end
end
include M1

module M2
    module M1
      class C1
        def m_2
          p '2'
        end
      end
    end
end
include M2

C1.new.m_2  -> error: method m_2 undefined


-----Original Message-----
From: jweirich@one.net [mailto:jweirich@one.net]
Sent: Wednesday, October 31, 2001 8:26 AM
To: ruby-talk ML
Subject: [ruby-talk:23982] Re: Overiding a method in another module


>>>>> "Mark" == Mark Hahn <mchahn@facelink.com> writes:

    Mark> Here is the situation that I am facing (see below).  I want
    Mark> to add method m_2 to class C1 and make sure instances of C2
    Mark> (any any other subclass of C1) respond to m_2.  I cannot
    Mark> subclass C1 to accomplish this because I have no way to
    Mark> change C2 to subclass my new subclass.  I cannot change the
    Mark> source of M1 because of the license.  Even if there wasn't a
    Mark> license issue, isn't reusability all about using other code
    Mark> without changing it?

    Mark> module M1    << This is other person's module
    Mark>   class C1
    Mark>     def m_1
    Mark>       ...
    Mark>     end
    Mark>   end
    Mark>   class C2 < C1
    Mark>     ...
    Mark>   end
    Mark> end

Just do this in your code somewhere ...

    module M1
      class C1
        def m_2
          ...
        end
      end
    end

Ruby classes are open, so you can add new methods to them without
touching the original source.

--
-- Jim Weirich     jweirich@one.net    http://w3.one.net/~jweirich
---------------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct,
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)