From: gotoken@... (GOTO Kentaro)
Date: 2000-11-22T04:02:20+09:00
Subject: [ruby-talk:6504] Re: redefining methods in a hierarchy.

In message "[ruby-talk:6503] redefining methods in a hierarchy."
    on 00/11/22, Hugh Sasse Staff Elec Eng <hgs@dmu.ac.uk> writes:
>If I have an object which I know to be a subclass of a subclass (at lease)
>and I want to override a method, I can do it in that object's class and
>all is well.  But if I can override the method higher up I get more power
>from my change.  My change may not just affect Fixnums, but it might be
>able to work on all numbers, for example.  Given the reflection abilities
>of Ruby, can I ask an object which class really handles a given method?
>Then I know where to make the change.

Are you looking for something like this?

  class Class
    def whereis(meth)
      meth = meth.id2name if meth.is_a? Symbol
      unless meth.is_a? String
	raise TypeError,
	  "wrong argument type #{meth.type} (expected String or Symbol)"
      end

      ancestors.find do |klass|
	klass.instance_methods.include? meth
      end
    end
  end

  p Fixnum.whereis :nonzero?  #=> Numeric
  p Fixnum.whereis :integer?  #=> Integer
  p Fixnum.whereis :zero?     #=> Fixnum
  p Array.whereis :find       #=> Enumerable

-- gotoken