"""
狀態模式
一個複雜物件改變它的內在狀態則允許改變它的行為
應用場景：一個複雜物件包含有很多個分支，則把這些分支抽象成一個個子類，該物件只需要去呼叫子類的公共介面。客戶端呼叫時，可以
根據狀態來選擇哪個子類來執行分支
"""
from abc import ABCMeta, abstractmethod


class State(object):
    """
    狀態抽象類
    """
    __metaclass__ = ABCMeta

    def __init__(self):
        pass

    @abstractmethod
    def handle
 
(self, context):
        pass


class StateA(State):
    def __init__(self):
        super(StateA, self).__init__()

    def handle(self, context):
        print("StateA:")
        print(context.status)


class StateB(State):
    def __init__(self):
        super(StateB, self).__init__()

    def handle
 
(self, context):
        print("StateB:")
        print(context.status)


class Context(object):
    def __init__(self, state):
        self._status = None
        self._state = state

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

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

    @property
 

    def state(self):
        return self._state

    @state.setter
    def state(self, state):
        self._state = state

    def handle(self):
        self._state.handle(self)


if __name__ == '__main__':
    state1 = StateA()
    state2 = StateB()

    context = Context(state1)
    context.status = "normal"
    context.handle()
    print("")

    context.state = state2
    context.status = "error"
    context.handle()