Async without external loop

Demonstrates that the state machine can have async callbacks even if the calling context is synchronous.

from statemachine import State
from statemachine import StateChart


class AsyncStateMachine(StateChart):
    initial = State("Initial", initial=True)
    processing = State()
    final = State("Final", final=True)

    start = initial.to(processing)
    finish = processing.to(final)

    async def on_start(self):
        return "starting"

    async def on_finish(self):
        return "finishing"

Executing

def sync_main():
    sm = AsyncStateMachine()
    result = sm.start()
    print(f"Start result is {result}")
    result = sm.send("finish")
    print(f"Finish result is {result}")
    print(list(sm.configuration))
    assert sm.final in sm.configuration


if __name__ == "__main__":
    sync_main()

Start result is starting
Finish result is finishing
[State('Final', id='final', value='final', initial=False, final=True, parallel=False)]