dynamic_role_switching_spec.rb

$:.unshift(File.dirname(__FILE__), ".")
require 'rubygems'
require 'rspec'

module Butler

  def self.extended base
    base.get_ready
  end

  def get_ready
    @place = []
  end
  
  def put_fork_on_the_left
    @place.unshift "fork"
    @place 
  end

  def put_knife_on_the_right
    @place.push "knife"
    @place 
  end
end

module Cook
  #Do something similar here

  def boil_water
    
  end

  def turn_on_stove
    
  end

  def place_boil_in_bag_into_pot

  end
end

module MakeDinner

  def follow_instructions
    turn_on_stove 
    boil_water
    place_boil_in_bag_into_pot
  end
end

module LayTable

  def follow_instructions
   put_fork_on_the_left
   put_knife_on_the_right 
  end
end

class MyActor
  #decide how we will make the actor know in which role they should perform the task
  def initialize role
    extend role
  end

  def perform task
    recall_how_to_do task 
    follow_instructions
  end

  private
  def recall_how_to_do something
    extend something
  end
end

describe "Something" do

  it "Something" do
    butler = MyActor.new Butler

    butler.perform(LayTable).should == ["fork","knife"]
  end
end

Changed self.included to self.extended

And now we've gotten rid of the eval :-)