From: Gregory Seidman <gsslist+ruby@...>
Date: 2006-04-11T23:29:32+09:00
Subject: Re: Adding in class attribute with a Module

On Tue, Apr 11, 2006 at 06:19:23AM +0900, TRANS wrote:
} > Does this count as ugly meta-programming?
} >
} > module M
} >   def self.included(klass)
} >     class << klass
} >       attr_accessor :m
} >     end
} >   end
} > end
} 
} Yep. That's Ugly Hack #1. What wrong with Ugly Hack #1, you ask?
} 
}   module N
}     include M
}   end
} 
}   class C
}     include N
}   end
} 
}   C.m
}   NoMethodError: undefined method `m' for C:Class

Yep, that's an issue. Well, you can do this:

module M
  OnIncludeProc = lambda do |klass|
    if klass.class == Module
      def klass.included(k)
        OnIncludeProc.call(k)
      end
    else
      class << klass
        attr_accessor :m
      end
    end
  end

  OnIncludeProc.call(self)

end

Yes, it's uglier. Yes, it conflicts with other #included tricks with modules
that include the module. It does work, though.

} T.
--Greg