sticky trigger

alarm.py

import random

class Sensor(object):
    OFFSET = 16
        
    def pop_next_pressure_psi_value(self):
        pressure_telemetry_value = self.sample_pressure()
        return Sensor.OFFSET + pressure_telemetry_value

    def __iter__(self):
        return iter(self.pop_next_pressure_psi_value, Ellipsis)

    @staticmethod
    def sample_pressure():
        # placeholder implementation that simulate a real sensor in a real tire
        pressure_telemetry_value = 6 * random.random() * random.random()
        return pressure_telemetry_value


class Alarm():
    def __init__(self):
        self.trigger = StickyTrigger(
            condition=lambda value : not 17 <= value <= 21,
            iterator=iter(Sensor())
        )
    def check(self):
        self.trigger.check()

    def is_alarm_on(self):
        return self.trigger.on

class StickyTrigger(object):

    def __init__(self, condition, iterator):
        self.__conditon = condition
        self.__iterator = iterator
        self.__on = False

    def check(self):
        value = self.__iterator.next()
        self.__on = self.__conditon(value) or self.on

    @property
    def on(self):
        return self.__on