FSM

FSM.md

Finite State Machine based on youtube video
The same solution splited to modules is here

from random import randint
from time import sleep

# _____________________________________________________
State = type("State", (object,), {})


class LightOn(State):

    @staticmethod
    def execute():
        print("Light is on")


class LightOff(State):

    @staticmethod
    def execute():
        print("Light is off")


# _____________________________________________________
class Transition(object):
    def __init__(self, to_state):
        self.to_state = to_state

    @staticmethod
    def execute():
        print("Transitioning")


# _____________________________________________________
class FSM(object):
    def __init__(self, asset_obj):
        self.asset_obj = asset_obj
        self.states = {}
        self.transitions = {}
        self.cur_state = None
        self.transition = None

    def set_state(self, state_name):
        self.cur_state = self.states[state_name]

    def switch_transition(self, transition_name):
        self.transition = self.transitions[transition_name]

    def execute(self):
        if self.transition:
            self.transition.execute()
            self.set_state(self.transition.to_state)
            self.transition = None
        self.cur_state.execute()


# _____________________________________________________

class Lamp(object):
    def __init__(self):
        self.FSM = FSM(self)
        self.light_on = True


if __name__ == '__main__':
    light = Lamp()

    light.FSM.states["on"] = LightOn()
    light.FSM.states["off"] = LightOff()

    light.FSM.transitions["to_on"] = Transition("on")
    light.FSM.transitions["to_off"] = Transition("off")

    light.FSM.set_state("on")

    for i in range(20):
        if randint(0, 2):
            if light.light_on:
                light.FSM.switch_transition("to_off")
                light.light_on = False
            else:
                light.FSM.switch_transition("to_on")
                light.light_on = True
        light.FSM.execute()
        sleep(1)