gistfile1.txt

# based on http://gist.github.com/339028

module Base
  module Plugins
    def plugins
      @plugins ||= []
    end
 
    def activate plugin
      plugins << plugin
      plugin = Base::Plugins.const_get(plugin.capitalize)
      plugin.activate(self) if plugin.respond_to?(:activate)
    end

    module Backward
      def self.activate(obj)
        obj.extend Redefinitions
      end
      module Redefinitions
        def say(what)
          p "say: #{what.reverse}"
        end
      end
    end
    
    module Loudness
      def self.activate(obj)
        obj.extend Redefinitions
      end
      module Redefinitions
        def say(what)
          p "say: #{what.upcase}"
        end
      end
    end
    
  end
end

module Base
  class Server
    include Plugins

    def say(what)
      p "say: #{what}"
      @config = "default"
    end
  end
end
 
s = Base::Server.new 
s.say        'hello world'
s.activate   'backward'
s.say        'hello world'

puts

s2 = Base::Server.new
s2.say       'hello world'
s2.activate  'loudness'
s2.say       'hello world'