From: Rick DeNatale <rick.denatale@...>
Date: 2006-10-19T09:42:16+09:00
Subject: Re: Mixin a module method as a class method

On 10/18/06, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
> 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
> --
> my religion is very simple.  my religion is kindness. -- the dalai lama

No need for the separate module for instance methods;

rick@frodo:/public/rubyscripts$ cat a1.rb
module Foo

  module ClassMethods
    def method_added(method)
      puts "Added #{method}"
    end
  end

  def self.included(other)
    other.extend ClassMethods
  end

  def foo
    42
  end
end

class Bar
  include Foo

  def bar
  end

  def baz
  end
end

p Bar.new.foo
rick@frodo:/public/rubyscripts$ ruby a1.rb
Added bar
Added baz
42


-- 
Rick DeNatale

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