From: Peter Vanbroekhoven <calamitas@...>
Date: 2005-09-11T23:50:11+09:00
Subject: Re: When an Array is not

On Sun, 11 Sep 2005, David A. Black wrote:

> You could also re-include Enumerable in Array after you've changed
> Enumerable.  Still, it does seem like some kind of optimization or
> special case for built-ins.  If you make your own the changes are
> propagated:
>
>  module M
>    def x; 1; end
>  end
>
>  class D
>    include M
>  end
>
>  D.new.x    # 1
>
>  module M
>    def y; 2; end
>  end
>
>  D.new.y    # 2

Actually the corresponding example would be something like this:

   module M
     def y ; 'y' ; end
   end

   module N
     def x ; 'x' ; end
   end

   class A
     include N
   end

   module N
     include M
   end

   A.new.x  # 'x'
   A.new.y  # NoMethodError
   A.ancestors  # [A, N, Object, Kernel]
   N.ancestors  # [N, M]

It has nothing to do with built-ins, it's a restriction of the way Ruby 
handles module inclusion. For more information, see the thread starting at 
[ruby-core:2068] http://rubyurl.com/vFI

Peter