设计模式之策略模式

摘要: 策略者模式： 定义了一个公共接口，根据不同的行为实现这个接口，使用Context调用封装的接口。
策略者模式思想：面向接口编程，而不是面向实现编程。

1. 公共接口：

class MDCash:
def acceptCash(self):
return

2. 根据上面定义的接口实现：

# 正常
class MDCashNormal(MDCash):
def acceptCash(self, params):
return params
# 返5
class MDCaseReturn(MDCash):
def acceptCash(self, params):
return params - 5
# 打9折
class MDCashRobate(MDCash):
def acceptCash(self, params):
return params - params * 0.1

3. 实现context，封装不同行为的接口。

class MDCashContext:
def __init__(self, cashStrategy):
self.cashStrategy = cashStrategy
def performPay(self, params):
print self.cashStrategy.acceptCash(params)

4. 使用

if __name__ == '__main__':
context = MDCashContext(cashStrategy=MDCaseReturn())
context.performPay(100)

context = MDCashContext(cashStrategy=MDCashNormal())
context.performPay(100)

context = MDCashContext(cashStrategy=MDCashRobate())
context.performPay(100)

5. 所有代码：

#encoding:utf-8

class MDCash:
def acceptCash(self):
return

class MDCashNormal(MDCash):

def acceptCash(self, params):
return params

class MDCaseReturn(MDCash):
def acceptCash(self, params):
return params - 5

class MDCashRobate(MDCash):
def acceptCash(self, params):
return params - params * 0.1

class MDCashContext:
def __init__(self, cashStrategy):
self.cashStrategy = cashStrategy
def performPay(self, params):
print self.cashStrategy.acceptCash(params)

if __name__ == '__main__':
context = MDCashContext(cashStrategy=MDCaseReturn())
context.performPay(100)

context = MDCashContext(cashStrategy=MDCashNormal())
context.performPay(100)

context = MDCashContext(cashStrategy=MDCashRobate())
context.performPay(100)

运行结果：

95
100
90.0