Python设计模式之状态模式原理与用法详解

#!/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):    passclass 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()