Design Pattern: Builder and Car

sports_car_builder.rb

class SportsCarBuilder
  def build
    car = ''
    # 1. build car frame
    car << "This is a sport car\n"
    # 2. add an engine
    car << "  with a powerful engine\n"
    # 3. add front wheels
    car << "  with two front wheels suitable for mountain paths\n"
    # 4. add back wheels
    car << "  with two back wheels suitable for mountain paths\n"
    # 5. add dashboard
    car << "  with a fancy sporty dashboard\n"
    # 6. add a energy source
    car << "  with a big fuel tank\n"
    # return the car
    car
  end
end