From: ara.t.howard@...
Date: 2006-10-19T00:14:01+09:00
Subject: Re: Mixin a module method as a class method

On Wed, 18 Oct 2006, Farrel Lifson wrote:

> Is it possible to mix in a module method to become a class method? I'd
> like to define the method_added method in a module and then mix it
> into a class like so
> module Foo
>  def self.method_added(method)
>    puts "Added #{method}"
>  end
> end
>
> class Bar
> include Foo
> def bar
> end
> def baz
> end
> end
> So that I get
> Added bar
> Added baz
> printed out. Is there any way to do this besides making Foo a class
> and subclassing Foo from it?
>
> Farrel

     harp:~ > cat a.rb
     module Foo
       #def self.method_added(method)
       def method_added(method)
         puts "Added #{method}"
       end
     end

     class Bar
       #include Foo
       extend Foo
       def bar
       end
       def baz
       end
     end

     harp:~ > ruby a.rb
     Added bar
     Added baz


if you need both instance and class methods to be in Foo, then you'll want:


     harp:~ > cat a.rb
     module Foo
       #def self.method_added(method)
       module ClassMethods
         def method_added(method)
           puts "Added #{method}"
         end
       end
       module InstanceMethods
         def foo() 42 end
       end
       def self.included other
         other.module_eval{
           extend ClassMethods
           include InstanceMethods
         }
       end
     end

     class Bar
       include Foo
       def bar
       end
       def baz
       end
     end

     p Bar.new.foo


     harp:~ > ruby a.rb
     Added bar
     Added baz
     42


-a
-- 
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