mockup v2

x.py

import time

# initialize an events dictionary that will later be populated with different
# functions to be called as events are identified by poll

global EVENTS


def poll(state):
    '''
    this polls the audrino and clock to see if there has been some event
    Right now we'll just use the clock to mock up events
    yields a pair of state, value of changed states from last polling
    '''

    prior_state = state.copy()
    while True:
        # update clock
        running = time.time() - state['start']
        state['clock'] = int(state['countdown'] - running)
        # find differences
        keys = state.keys() | prior_state.keys()
        delta = {}
        for key in keys:
            if state.get(key) != prior_state.get(key):
                delta[key] = state[key]

        if not delta:
            # nothing has happened
            time.sleep(.1)
            continue
        # we are making this a generator because generators are cool
        prior_state = state.copy()
        for key, value in delta.items():
            yield key, value

    
def ignite_boosters(state):
    print('igniting boosters')
    if state.get('enable_boosters') != True:
        print('\t boosters have failed to ignire')
    else:
        print('\t boosters go')
        state['boosters'] = True


def liftoff(state):
    if state['boosters'] == True:
        print('lift off')
    else:
        print('critical failure')
    state['done'] = True # causes program to stop

def clock(state):
    '''
    generic function to handle timed events
    '''
    print('T minus {}'.format(state['clock']))
    event = 'clock_{}'.format(state['clock'])
    if event in EVENTS:
        func = EVENTS[event]
        func(state)

def abort(state):
    print('abort button pressed!')
    print('shutting down')
    state['done'] = True

def t_minus_4(state):
    '''
    to mock up a button press, we will pretend that the button changed at T
    minus 4 by changing a state

    here we pretend to enable/disable the boosters, something necessary for the 
    booster ignitition
    '''
    state['enable_boosters'] = True
    # removing comment from next line will cause a booster failure 
    #state['enable_boosters'] = False

    # removing comment from next line will cause an abort event, as if a stop
    # button pushed 
    # state['abort'] = True


EVENTS = {
        'clock': clock,
        'clock_4': t_minus_4,
        'clock_3': ignite_boosters,
        'clock_0': liftoff,
        'abort': abort,
        #'boosters': confirm_boosters, # event called when booster state changes
        }

def main():
    state = {
        'start': time.time(),
        'countdown': 5,
        'clock': 5,
        'ok': True,
        'boosters': False,
        }

    for event, value in poll(state):
        # remove comments to watch how events pop up
        #print('DEBUG: event = {}, value = {}'.format(event, value))
        if event == 'done' and value == True:
            break

        if event in EVENTS:
            func = EVENTS[event]
            func(state)

if __name__ == '__main__':
    main()