设计模式：状态模式

 

大话设计模式: 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)

# 状态类
class State(object):
    def __init__(self):
        pass

    def write_program(self, w):
        pass


# 上午类
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()


# 中午类
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()


# 下午类
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()


# 晚上睡类
class SleepState(State):

    def write_program(self, w):
        print("当前时间:%s点," % w.hour, "不行了,睡着了")


# 外在worker类
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)


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()