python设计模式第九天【策略模式】

1. 定义

对一系列算法进行封装，为所有算法定义一个抽象的算法接口，可以平滑的进行算法切换

2. 策略模式的UML图

3.代码实现

#!/usr/bin/env python
#! _*_ coding:UTF-8 _*_

from abc import ABCMeta, abstractmethod

class Context(object):

    def setStrategy(self, strategy):
        self.__strategy = strategy

    def operation(self):
        self.__strategy.algorithmInterface()

class Strategy(object):

    @abstractmethod
    def algorithmInterface(self):
        pass

class ConcreteStrategyA(Strategy):

    def algorithmInterface(self):
        print "strategy A"

class ConcreteStrategyB(Strategy):

    def algorithmInterface(self):
        print "strategy B"

if __name__ == "__main__":

    context = Context()

    concreteStrategyA = ConcreteStrategyA()
    concreteStrategyB = ConcreteStrategyB()

    context.setStrategy(concreteStrategyA)
    context.operation()

    context.setStrategy(concreteStrategyB)
    context.operation()

结果：

/Users/liudaoqiang/PycharmProjects/numpy/venv/bin/python /Users/liudaoqiang/Project/python_project/day09_strategy/strategy_test.py
strategy A
strategy B

Process finished with exit code 0