non_blocking_hw_api.py

import time

class RangeSensor:

    def __init__(self):
        pass

    def make_generator(self):
        t_end = time.time() + 0.1
        # tell sensor to start measurement
        while time.time() < t_end:       # while it isn't done yet
            yield None                   # yield None
        # read the result from the sensor
        yield 'result'

    def range(self):
        # the blocking call creates a generator and waits until it stops
        local_generator = self.make_generator()
        while True:
            try:
                val = next(local_generator)
            except StopIteration:
                break
            if val is not None:
                return val

    def range_non_blocking(self):
        # the non blocking call creates a generator if necessary and returns its current value
        # when no new value is available, it can either return None or the previous value
        try:
            val = next(self.range_generator)
        except AttributeError:
            self.range_generator = self.make_generator()
            val = next(self.range_generator)
        except StopIteration:
            self.range_generator = self.make_generator()
            val = next(self.range_generator)
        return val

class Accel:
    def x(self):
        return(1)

rs = RangeSensor()
accel = Accel()

# example 1
tw_end = time.time() + 0.3
while time.time() < tw_end:
    val = rs.range_non_blocking()
    if val is None:
        print('...', end='\r')
    else:
        print(val)

# example 2
tw_end = time.time() + 0.3
while time.time() < tw_end:
    print(accel.x(), rs.range_non_blocking())
    time.sleep(0.025)