使用多个简单的对象构造一个复杂的对象

使用场景

  1. 肯德基套餐场景

Demo

  1. """
  2. 建造者模式
  3. """
  4. from functools import reduce
  7. class Item:
  8.     def name(self):
  9.         raise NotImplementedError
  11.     def packing(self):
  12.         raise NotImplementedError
  14.     def price(self):
  15.         raise NotImplementedError
  18. class Packing:
  19.     def pack(self):
  20.         raise NotImplementedError
  23. class Wrapper(Packing):
  24.     def pack(self):
  25.         return 'wrapper'
  28. class Bottle(Packing):
  29.     def pack(self):
  30.         return 'bottle'
  33. class Burger(Item):
  34.     def packing(self):
  35.         return Wrapper()
  38. class VegBurger(Burger):
  39.     def name(self):
  40.         return 'vegburger'
  42.     def price(self):
  43.         return 33.2
  46. class ChickenBurger(Burger):
  47.     def name(self):
  48.         return "chickenburger"
  50.     def price(self):
  51.         return 35.1
  54. class ColdDrink(Item):
  55.     def packing(self):
  56.         return Bottle()
  59. class Pepsi(ColdDrink):
  60.     def name(self):
  61.         return self.__class__
  63.     def price(self):
  64.         return 10.2
  67. class Coke(ColdDrink):
  68.     def name(self):
  69.         return self.__class__
  71.     def price(self):
  72.         return 15.3
  75. class Meal:
  76.     def __init__(self):
  77.         self.items = []
  79.     def add(self, item):
  80.         self.items.append(item)
  82.     def prices(self):
  83.         return reduce(lambda x, y: x.price() + y.price(), self.items)
  86. class MealBuilder:
  87.     def prepare_a_meal(self):
  88.         meal = Meal()
  89.         meal.add(ChickenBurger())
  90.         meal.add(Coke())
  91.         return meal
  93.     def prepare_b_meal(self):
  94.         meal = Meal()
  95.         meal.add(Pepsi())
  96.         meal.add(VegBurger())
  97.         return meal
  100. if __name__ == '__main__':
  101.     m_b = MealBuilder()
  102.     a_meal = m_b.prepare_a_meal()
  103.     print("a套餐的价格是:", a_meal.prices())
  104.     b_meal = m_b.prepare_b_meal()
  105.     print("b套餐的价格是:", b_meal.prices())