大话设计模式Python实现-状态模式

状态模式(State Pattern):当一个对象的内在状态改变时允许改变其行为，这个对象看起来像是改变了其类

下面是一个状态模式的demo：

 #!/usr/bin/env python
 # -*- coding:utf-8 -*- __author__ = 'Andy'
 """
 大话设计模式
 设计模式——状态模式
 状态模式(State Pattern):当一个对象的内在状态改变时允许改变其行为，这个对象看起来像是改变了其类
 应用场景:当控制一个对象的状态转换的条件表达式过于复杂时,把状态的判断逻辑转移到表示不同状态的一系列类当中,可以把复杂的判断逻辑简化
 (当一个对象的行为取决于它的状态,并且它必须在运行时刻根据状态改变他的行为)
 """
 class State(object):
     def __init__(self):
         pass     def write_program(self, w):
         pass class Work(object):     def __init__(self):
         self.hour = 9
         self.curr = ForenoonState()     def set_state(self, s):
         self.curr = s     def write_program(self):
         self.curr.write_program(self) class ForenoonState(State):     def write_program(self, w):
         if w.hour < 12:
             print "当前时间:%s点,"%w.hour,"精神百倍"
         else:
             w.set_state(AfternoonState())
             w.write_program() class AfternoonState(State):     def write_program(self, w):
         if w.hour < 17:
             print "当前时间:%s点,"%w.hour,"状态还行,继续努力"
         else:
             w.set_state(EveningState())
             w.write_program() class EveningState(State):     def write_program(self, w):
         if w.hour < 21:
             print "当前时间:%s点,"%w.hour,"加班呢,疲劳了"
         else:
             w.set_state(SleepState())
             w.write_program() class SleepState(State):     def write_program(self, w):
         print "当前时间:%s点,"%w.hour,"不行了,睡着了" if __name__=="__main__":
     work = Work()
     work.hour = 9
     work.write_program()
     work.hour = 15
     work.write_program()
     work.hour = 20
     work.write_program()
     work.hour = 22
     work.write_program()