Delegators and composition in Ruby

gistfile1.rb

class Kitchen
  def prepare_hamburger
    return ( %w/ artisinal_bun niman_ranch_beef cowgirl_creamery_bleu_cheese lettuce central_valley_avocado/.
      join ', ' ) + " hamburger."
  end

  def generate_mixin
    Module.new do
      def prepare_hamburger
        puts "Enjoy a: " + @kitchen.prepare_hamburger
      end
    end
  end
end

class Restaurant
  def initialize(name)
    @name    = name
    @kitchen = Kitchen.new
    self.extend @kitchen.generate_mixin
  end
end


my_resto = Restaurant.new "The Stinky Cow"
my_resto.prepare_hamburger

resto.rb

#!/usr/bin/env ruby
#
# The Goal:  Use composition effectively.  A Restaurant purports to "prepare a hamburger," but we
# know that it is actually the responsibility of the kitchen to do the work.
#
# Key feature:  the token used for the action is the SAME between the two entitites `prepare_hamburger`.
#
# Desired:  A way to have Restaurant delegate :prepare_hamburger to Kitchen **AND**
#           **do not** define the wrapper :prepare_hamburger on Restaurant.

class Kitchen
  def prepare_hamburger
    return ( %w/ artisinal_bun niman_ranch_beef cowgirl_creamery_bleu_cheese lettuce central_valley_avocado/.
      join ', ' ) + " hamburger."
  end
end

class Restaurant
  def initialize(name)
    @name    = name
    @kitchen = Kitchen.new
  end

  def prepare_hamburger
    puts "Enjoy a: " + @kitchen.prepare_hamburger
  end
end


my_resto = Restaurant.new "The Stinky Cow"
my_resto.prepare_hamburger

If your goal is to use composition effectively, and then you call #extend, you've failed, because mixins are inheritance, not composition. ;)

That said, I sorta agree with James; I'm also not sure what the point is... :/