From: Rick DeNatale <rick.denatale@...>
Date: 2007-11-06T23:30:05+09:00
Subject: Re: Superclass of a module

On 11/5/07, Todd Corenson <todd@browsersys.com> wrote:
> Does this make Foo a singleton class of Module?  This would explain how
> Foo could respond to super, yet have no superclass.  But this would
> still be strange because
>
> module Foo
>   def self.append_features(b)
>     super
>   end
> end
>
> would make append_features a module method and yet
> Module.new.respond_to?(:append_features, true) is true.  For a class,
> this implies that append_features would be an instance method.  I take
> it this works differently for modules?

No, Foo is an instance of Module.

module Foo
 def self.append_features(b)
   super
 end
end

The self.append_features in the def means that we are defining the
method in the context
of the singleton class of Foo.  Try running this:
class Module
  def provides_method(meth)
    instance_methods.include?(meth.to_s) ? "provides #{meth}" : "does
not provide #{meth}"
  end
end

module Foo
  def self.append_features(b)
    puts "I am #{self}"
    puts "My class is #{self.class} which
#{self.class.provides_method(:append_features)}"
    sing_class = class <<self; self;end
    puts "My singleton class is #{sing_class}  which
#{sing_class.provides_method(:append_features)}"
    super
  end
end

class C
  include Foo
end

which produces the following output:

I am Foo
My class is Module which does not provide append_features
My singleton class is #<Class:Foo>  which provides append_features


-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/