策略模式如图所示：

代码如下：
#!/usr/bin/env python
# -*- coding:utf-8 -*-

class Strategy:
    "抽象算法类"

    def algorithmInterface(self):
        "抽象方法"
        pass

class ConcreteStrategyA(Strategy):
    "具体算法类A"

    def algorithmInterface(self):
        "具体实现方法"

        print(‘Algorithm A‘)


class ConcreteStrategyB(Strategy):
    "具体算法类A"

    def algorithmInterface(self):
        "具体实现方法"

        print(‘Algorithm B‘)


class ConcreteStrategyC(Strategy):
    "具体算法类A"

    def algorithmInterface(self):
        "具体实现方法"

        print(‘Algorithm C‘)

class Context:
    "上下文类"

    def __init__(self, strategy):
        self.strategy = strategy

    def contextInterface(self):
        "上下文接口"

        self.strategy.algorithmInterface()

if __name__ == ‘__main__‘:
    "相同调用方法不同策略"

    context = Context(ConcreteStrategyA())
    context.contextInterface()

    context = Context(ConcreteStrategyB())
    context.contextInterface()

    context = Context(ConcreteStrategyC())
    context.contextInterface()

学习转载于：www.pythonfan.org

python实现策略模式