# -*- coding: utf-8 -*-

from abc import ABCMeta, abstractmethod


class State(metaclass=ABCMeta):
    @abstractmethod
    def do_this(self):
        pass


class StartState(State):
    def do_this(self):
        print("start state")


class StopState(State):
    def do_this(self):
        print("stop state")


class TVContext(State):
    def __init__(self):
        self.state = None

    def get_state(self):
        return self.state

    def set_state(self, state):
        self.state = state

    def do_this(self):
        self.state.do_this()


if __name__ == '__main__':
    context = TVContext()

    start = StartState()
    stop = StopState()

    context.set_state(start)
    context.do_this()

    context.set_state(stop)
    context.do_this()
"""
start state
stop state
"""

# -*- coding: utf-8 -*-

# 接口
class ComputerState(object):
    name = "state"
    allowed = []

    def switch(self, state):
        if state.name in self.allowed:
            print("switch state: {}".format(state.name))
            self.__class__ = state
        else:
            print("state not allowed")

    def __str__(self):
        return self.name


# 具体实现
# 开机
class On(ComputerState):
    name = "on"
    allowed = ["off", "hibernate"]


# 关机
class Off(ComputerState):
    name = "off"
    allowed = ["on"]


# 休眠
class Hibernate(ComputerState):
    name = "hibernate"
    allowed = ["on", "off"]


# 客户端
class Computer(object):
    def __init__(self):
        self.state = Off()  # 初始状态是关机状态

    def change(self, state):
        self.state.switch(state)


if __name__ == '__main__':
    computer = Computer()

    # 开机 -> 休眠 -> 关机
    computer.change(On)
    computer.change(Hibernate)
    computer.change(Off)

    # 关机的请情况下休眠
    computer.change(Hibernate)
"""
switch state: on
switch state: hibernate
switch state: off

state not allowed
"""