python 状态模式

import abc

‘‘‘
例子：灯的状态
‘‘‘


class AbsStatus(abc.ABC):

    @abc.abstractmethod
    def action(self, context): ...


class Bulb:
    def __init__(self, status: AbsStatus):
        self._status = status

    @property
    def status(self):
        return self._status

    @status.setter
    def status(self, value: AbsStatus):
        self._status = value

    def action(self):
        self.status.action(self)


class OnStatus(AbsStatus):

    def action(self, context):
        print("当前状态:开灯")
        context.status = OffStatus()


class OffStatus(AbsStatus):

    def action(self, context):
        print("当前状态:关灯")
        context.status = OnStatus()


buld = Bulb(OffStatus())
buld.action()   　　# 当前状态:关灯
buld.action()   　　# 当前状态:开灯
buld.action()　　　　# 当前状态:关灯
buld.action()　　　　# 当前状态:开灯