Python中的简单状态机

from transitions import Machine

class MyObject(object):
    def __init__(self):
        self.machine = Machine(model=self, states=['A', 'B', 'C'], initial='A')
        self.machine.add_transition('to_B', 'A', 'B')
        self.machine.add_transition('to_C', 'B', 'C')
        self.machine.add_transition('to_A', 'C', 'A', after='reset_counter')

    def reset_counter(self):
        self.counter = 0

obj = MyObject()
print(obj.state)  # 输出当前状态：A
obj.to_B()  # 触发状态转换：A -> B
print(obj.state)  # 输出当前状态：B
obj.to_C()  # 触发状态转换：B -> C
print(obj.state)  # 输出当前状态：C
obj.to_A()  # 触发状态转换：C -> A，并执行重置计数器的动作
print(obj.state)  # 输出当前状态：A