策略模式学习与记录
- 设计原则
- 找出应用中可能需要改变之处, 把他们独立出来, 不要和那些不需要改变的代码混在一起
- 针对接口编程而不是针对实现编程
不要被类的实现拖垮你的代码, 针对接口编程的关键, 在于利用多态 执行时会根据状况执行到真正的行为
代码实现如下
import abc
class FlyBehavior:
""" pass """
__metaclass__ = abc.ABCMeta
@classmethod
@abc.abstractmethod
def fly(cls):
""" pass """
class FlyWithWings(FlyBehavior):
""" pass """
@classmethod
def fly(cls):
""" pass """
print('I can fly')
class FlyNoWay(FlyBehavior):
""" pass """
@classmethod
def fly(cls):
""" pass """
class QuackBehavior:
""" pass """
__metaclass__ = abc.ABCMeta
@classmethod
@abc.abstractmethod
def quack(cls):
""" pass """
class Quack(QuackBehavior):
""" pass """
@classmethod
def quack(cls):
""" pass """
print('I can quack ... gua gua gua !')
class Squeak(QuackBehavior):
""" pass """
@classmethod
def quack(cls):
""" pass """
print('I can quack ... zhi zhi zhi !')
class QuackNotWay(QuackBehavior):
""" pass """
@classmethod
def quack(cls):
""" pass """
class Duck:
""" pass """
def __init__(self, _fly, _quack):
""" pass """
self.__quack = _quack()
self.__fly = _fly()
def swim(self):
""" pass """
print('swiming ...!')
def display(self):
""" pass """
self.__quack.quack()
self.__fly.fly()
self.swim()
class MallardDuck(Duck):
""" pass """
def __init__(self, _fly, _quack):
""" pass """
print('MallardDuck')
super(MallardDuck, self).__init__(_fly, _quack)
class RubberDuck(Duck):
""" 橡皮鸭 """
def __init__(self, _fly, _quack):
""" pass """
print('RubberDuck')
super(RubberDuck, self).__init__(_fly, _quack)
class DecoyDuck(Duck):
""" 诱饵鸭 """
def __init__(self, _fly, _quack):
""" pass """
print('DecoyDuck')
super(DecoyDuck, self).__init__(_fly, _quack)
if __name__ == '__main__':
mallar = MallardDuck(FlyWithWings, Quack)
mallar.display()
rubber = RubberDuck(FlyNoWay, Squeak)
rubber.display()
decoy = DecoyDuck(FlyNoWay, QuackNotWay)
decoy.display()
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