From: Jean-Hugues ROBERT <jean_hugues_robert@...>
Date: 2002-05-05T00:29:20+09:00
Subject: Re: Class methods defined in a module, how-to ?

At 23:31 04/05/2002 +0900, you wrote:
>Jean-Hugues ROBERT wrote:
> >
> > At 20:31 04/05/2002 +0900, you wrote:
> > >    module MyModule
> > >       def foo()
> > >          print "foo"
> > >       end
> > >    end
> > >    class MyClass
> > >       extend MyModule
> > >    end
> > >    MyClass.foo() # work :-)
> > >
> > >
> > >Guy Decoux
> >
> > Thanks. However I would like to *include* the module, not extending it.
>
>You aren't extending the Module.
>You are extending MyClass with the contents of the module.

True, sorry for the confusion.

>Sounds like you need to split up your module in a part you want to
>include (instance methods) and a part you want to extend your class with
>(class methods).

Yes, that would do the job. Maybe there is a way to get by with a single 
module. I was wondering if some "included()" hook existed (similar to 
inherited() for classes), and I found that "append_features()" is the hook 
called when a module is included.

So: What I intend (to include class methods defined in a module)
module MyModule
    def MyModule.foo()
    end
end
class MyClass
   include MyModule # I want to include both class & instance methods
end
MyClass.foo() # Calls foo() class method defined in module, broken.

Could be written:
module MyModule
   def append_features( includer )
     super( includer)
     includer.instance_eval( "
       # Here comes the definitions of included class methods
       def foo() end
     ")
   end
end
class MyClass
   include MyModule
end
MyClass.foo()

However this does not work either... apparently append_features() is not 
called. Additionnal 1) the construct is ugly, relies on eval and 2) there 
is no way to later on introspect MyClass and know that foo() class method 
was defined in MyModule.

Any hints ?

Jean-Hugues