Event in callbacks should be optional.

[tompreston]

The InputEventListener.register function should have a flag to optionally send events to callback functions.

import pifacedigitalio

def somefunction():
    """This function has no event argument."""
    pass

listener = pifacedigitalio.InputEventListener()
l.register(0, p.IODIR_DIR, somefunction, send_event=False)
l.activate()

somefunction is not passed an event object because send_event was set to False in the register function. send_event will default to True.

I'm not sure whether this should be implemented or not because it allows programmers to be inconsistent in callback definitions and you can just ignore the event anyway.

It is useful for directly calling existing library functions, that don't accept event objects. For example:

import robot

listener = pifacedigitalio.InputEventListener()
l.register(0, p.IODIR_DIR, robot.walk, send_event=False)
l.activate()

robot.walk() is not expecting any event objects so we do not send it any. Currently this can be wrapped up with:

import robot

def do_robot_walk(event):
    robot.walk()

listener = pifacedigitalio.InputEventListener()
l.register(0, p.IODIR_DIR, do_robot_walk)
l.activate()