From: Daniel Schierbeck <daniel.schierbeck@...>
Date: 2006-06-15T23:38:24+09:00
Subject: Re: Why the lack of mixing-in support for Class methods?

transfire@gmail.com wrote:
> I assume you are doing this for the challenge / learning expience....

That, and it's nice to have an implementation that fits with the 
interface we have pretty much agreed on (well, matz has).

> #included is not the best method to use since it is a callback. While
> you could override #include itself, probably the most appropriate
> method to use is #append_features. This is the method include calls to
> do it's "magic".
> 
> Also, after defining the class_extension method for Module, you'll want
> to undefine it for Class, since it has no relevance there:
> 
>   class Class
>     undef_method :class_extension
>   end

Thanks for the feedback, here's the updated version.

   class Module
     def class_extension(&block)
       @class_extension ||= Module.new do
         def self.append_features(mod); end
       end
       @class_extension.module_eval(&block) if block_given?
       @class_extension
     end

     def append_features(mod)
       mod.extend(class_extension)
       if mod.instance_of? Module and mod.respond_to? :class_extension
         mod.send(:class_extension).send(:include, class_extension)
       end
     end
   end

   class Class
     undef_method :class_extension
   end

#class_extension should probably be private, right?


Daniel