From: Andrew Wagner <wagner.andrew@...>
Date: 2010-07-26T13:48:11+09:00
Subject: Beginning meta-programming question

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I'm pretty new to ruby, and just playing around. I can't work out why the
following won't work, though:

   1.  module TrackInheritors
   2.    def self.extended(parent)
   3.      class << parent
   4.        puts self
   5.        @@inheritors = []
   6.
   7.        def self.inheritors
   8.          @@inheritors
   9.        end
   10.
   11.        def self.inherited(child)
   12.          @@inheritors << child
   13.        end
   14.      end
   15.    end
   16.  end
   17.
   18.  class Parent
   19.    extend TrackInheritors
   20.  end
   21.
   22.  class Child1 < Parent
   23.  end
   24.
   25.  class Child2 < Parent
   26.  end
   27.
   28.  puts Parent.inheritors
   29.
   30.  # -:28: undefined method `inheritors' for Parent:Class
   (NoMethodError)

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