From: cppcodeguy@...
Date: 2010-07-26T15:26:52+09:00
Subject: Re: Beginning meta-programming question

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 I'm a noob myself so sorry if I give incorrect information but I think you=
 have a going out of scope issue. The inheirtors method is defined within t=
he class that starts on line 3. However, the class it's put in is inside th=
e extended method on line 2, so what I think is going on is that by the tim=
e you're trying to the inheirtors method, its class has already gone out of=
 scope since it's called after the extended method has ended.


=20

-----Original Message-----
From: Andrew Wagner <wagner.andrew@gmail.com>
To: ruby-talk ML <ruby-talk@ruby-lang.org>
Sent: Sun, Jul 25, 2010 9:48 pm
Subject: Beginning meta-programming question


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 =3D []

   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)




=20

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