Python設計模式之狀態模式原理與用法詳解

#!/usr/bin/env python
# -*- coding:utf-8 -*-
__author__ = 'Andy'
"""
大話設計模式
設計模式——狀態模式
狀態模式(State Pattern):當一個對象的內在狀態改變時允許改變其行為，這個對象看起來像是改變了其類
應用場景:當控制一個對象的狀態轉換的條件表達式過于復雜時,把狀態的判斷邏輯轉移到表示不同狀態的一系列類當中,可以把復雜的判斷邏輯簡化
(當一個對象的行為取決于它的狀態,并且它必須在運行時刻根據狀態改變他的行為)
"""
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 "當前時間:%s點,"%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 "當前時間:%s點,"%w.hour,"狀態還行,繼續努力"
    else:
      w.set_state(EveningState())
      w.write_program()
class EveningState(State):
  def write_program(self, w):
    if w.hour < 21:
      print "當前時間:%s點,"%w.hour,"加班呢,疲勞了"
    else:
      w.set_state(SleepState())
      w.write_program()
class SleepState(State):
  def write_program(self, w):
    print "當前時間:%s點,"%w.hour,"不行了,睡著了"
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()