optimize portion of code for similar event callbacks in RPi.GPIO (python on Raspberry Pi)

Question

I have a working code built around RPi.GPIO module and want to optimize a certain part that I feel it does not fit well cosmetically (not the whole, only a part of the code) -- except that I don't know how.

Here is a code to exemplify the context. The "offending" lines are just below the comment # question: how to optimize these lines? . I explicitly need the calls to be individual, one of the reasons being "in this case, the callback functions are run sequentially, not concurrently" (quote from docs), which I prefer for my particular usage.

Documentation for RPi.GPIO can be found here , but there's not much to read and I assume the callback style can be found in other situations too.

#!/usr/bin/env python

# RPi.GPIO module for Raspberry Pi https://pypi.python.org/pypi/RPi.GPIO
import RPi.GPIO as GPIO
import sys
import os
import time

class test(object):
    def __init__(self):
        pass

    def main(self):
        # consider BCM port numbering convention
        GPIO.setmode(GPIO.BCM)
        ports = [16, 20, 23]    # 3 ports only for this example, might be n ports
                                # actual port number is not relevant to question
        for i, port in enumerate(ports):
            # setup port direction & internal pull-up
            GPIO.setup(port, GPIO.IN, pull_up_down=GPIO.PUD_UP)
            # setup interrupt movement sense
            GPIO.add_event_detect(port, GPIO.FALLING)

        # question: how to optimize these lines? (compact in a loop or something)
        GPIO.add_event_callback(16, self.do_something_1)
        GPIO.add_event_callback(20, self.do_something_2)
        GPIO.add_event_callback(23, self.do_something_3)
        # etc. (might be n event callbacks, not just 3)

        while True:
            time.sleep(1)

    # some internal calls or even as separate external file(name) modules
    def do_something_1(self, from_port):    # for first port in ports
        print("called from port %s" % (from_port))
    def do_something_2(self, from_port):    # for second port in ports
        print("called from port %s" % (from_port))
    def do_something_3(self, from_port):    # for third port in ports
        print("called from port %s" % (from_port))
    # etc. (might be n defined functions, not just 3)

if __name__ == "__main__":
    try:
        app = test()
        app.main()
    except KeyboardInterrupt:
        print (" exit via Ctrl+C")
    finally:
        GPIO.cleanup()
        try:
            sys.exit(0)
        except SystemExit:
            os._exit(0)

So, question: what should I do with those 3 (or generic other random number) lines ?

Answer 1

How are the numbers/names in the callbacks determined? If it's arbitrary, you're probably doing it just fine at the moment.

That said, you could create a list of numbers-function tuples and then call them all in a for loop? But this isn't much better imho.

callback_pairs = [(16, "do_something_1"), (20, "do_something_2"), (23, "do_something_3")]
for n, fname in callback_pairs: 
    GPIO.add_event_callback(n, getattr(self, fname))

You could get rid of the getattr nastiness by just directly referencing self.do_something_[123] in the list of pairs, too.

What you're doing now isn't wrong though.