read from a joystick device that blocks when held in the same direction, to control a character walking, using asyncio

concurrent_joystick.py

import asyncio

import aiofiles  # third party package, install from pip


# bytes outputted by the imaginary joystick device:
CENTER = b'x'
NORTH = b'n'
EAST = b'e'
SOUTH = b's'
WEST = b'w'

VELOCITIES = {
  CENTER: (0, 0),
  NORTH: (0, 1),
  EAST: (1, 0),
  SOUTH: (0, -1),
  WEST: (-1, 0)
}

DT = 0.1  # timestep


class Walker:
  def __init__(self):
    self.direction = CENTER
    self.x = 0
    self.y = 0
    
walker = Walker()

async def read_joystick():
  async with aiofiles.open('/dev/input/joystick', 'rb') as f:
    while True:
      walker.direction = await f.read(1)

async def walk():
  while True:
    print('I’m at x={} y={}'.format(walker.x, walker.y))
    
    vx, vy = VELOCITIES[walker.direction]
    walker.x += vx * DT
    walker.y += vy * DT
    
    await asyncio.sleep(DT)

async def main():
  await asyncio.gather(
    read_joystick(),
    walk()
  )
    
loop = asyncio.get_event_loop()  # in python ≥3.7, just use asyncio.run(main())
loop.run_until_complete(main())
loop.close()