Looping state machine

This example demonstrates that you can call an event as a side-effect of another event. The event will be put on an internal queue and processed in the same loop after the previous event in the queue is processed.

from statemachine import State
from statemachine import StateMachine


class MyStateMachine(StateMachine):
    startup = State(initial=True)
    test = State()

    counter = 0
    do_startup = startup.to(test, after="do_test")
    do_test = test.to.itself(after="do_test")

    def on_enter_state(self, target, event):
        self.counter += 1
        print(f"{self.counter:>3}: Entering {target} from {event}")

        if self.counter >= 5:
            raise StopIteration

Let’s create an instance and test the machine.

sm = MyStateMachine()

try:
    sm.do_startup()
except StopIteration:
    pass

1: Entering Startup from __initial__
2: Entering Test from do_startup
3: Entering Test from do_test
4: Entering Test from do_test
5: Entering Test from do_test