Design Pattern: Builder and Car

sports_car_builder_v2.rb

class SportsCarBuilder
  attr_reader :car
  
  def initialize
    @car = ''
  end
  
  def build_car_frame
    car << "This is a sport car\n"
  end
  
  def add_engine
    car << "  with a powerful engine\n"
  end
  
  def add_front_wheels
    car << "  with two front wheels suitable for mountain paths\n"
  end

  def add_back_wheels
    car << "  with two back wheels suitable for mountain paths\n"
  end
  
  def add_dashboard
    car << "  with a fancy sporty dashboard\n"
  end
  
  def add_energy_source
    car << "  with a big fuel tank\n"
  end
end