python_statemachine_traffic_light_cycle_transitions.py

1oil from statemachine import StateMachine, State
2
3
4class TrafficLightMachine(StateMachine):
5    "A traffic light machine"
6    green = State(initial=True)
7    yellow = State()
8    red = State()
9
10    cycle = (
11        green.to(yellow)
12        | yellow.to(red)
13        | red.to(green)
14    )
15
16
17def main():
18    sm = TrafficLightMachine()
19    print(f"Initial state: {sm.current_state.id}")
20
21    sm.cycle()
22    print(f"After one cycle: {sm.current_state.id}")
23
24    sm.cycle()
25    print(f"After two cycles: {sm.current_state.id}")
26
27
28if __name__ == "__main__":
29    main()