Python设计模式之备忘录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――备忘录模式
备忘录模式(Memento Pattern):不破坏封装性的前提下捕获一个对象的内部状态，并在该对象之外保存这个状态,这样已经后就可将该对象恢复到原先保存的状态
"""
# 发起人类
class Originator(object):
  def __init__(self, state):
    self.state = state
  def create_memento(self):
    return Memento(self.state)
  def set_memento(self, memento):
    self.state = memento.state
  def show(self):
    print "当前状态 ", self.state
# 备忘录类
class Memento(object):
  def __init__(self, state):
    self.state = state
# 管理者类
class Caretaker(object):
  def __init__(self,memento):
    self.memento = memento
if __name__ == "__main__":
  # 初始状态
  originator = Originator(state='On')
  originator.show()
  # 备忘录
  caretaker = Caretaker(originator.create_memento())
  # 修改状态
  originator.state = 'Off'
  originator.show()
  # 复原状态
  originator.set_memento(caretaker.memento)
  originator.show()