Freezing with no error codes using non-standard library

Question

I'm doing some work with a MIDI controller called the Novation Launchpad that has a python module available to import and use.

My code keeps getting stuck on the line LP = launchpad.Launchpad(). So here is how I've attempted to de-bug:

import launchpad
print "I've started"
LP = launchpad.Launchpad()
LP.Open()
print "I worked!"

The programme never prints I've worked so I know my issue is in the creation of the Launchpad instance.

Using a friends laptop we've had no issues. I've had intermittent issues with it working and not working and really don't even know where to start looking!

how do you know it that it is stuck in `LP = launchpad.Launchpad()` and not in `LP.Open()`? — hitzg, Apr 24 '15 at 15:52
Perhaps you could hit ctrl-C while the program is apparently frozen. If the `launchpad` module is stuck in an infinite loop, the subsequent stack trace could give you a hint as to where the problem lies. This is assuming that you're willing to debug third-party code. — Kevin, Apr 24 '15 at 15:52
Since I don't know `launchpad` this is only a guess: is `Open()` supposed to access some hardware? Maybe it doesn't find it and is waiting for it to become accessible? — hitzg, Apr 24 '15 at 15:54
I've also tried without the `LP.Open()` command and that's where it seems to get hung up. Also, the hardware it is using is attached and is recognisable by `pygame.midi` and also various DAWs. I've tried a more complex script using the commands and it has no problems at all, I'm a bit stumped to be honest.. I'll post the script that runs above. — amitchone, Apr 24 '15 at 16:02

score 0 · Accepted Answer · answered Apr 24 '15 at 16:06

So, after finding a programme that would run with those commands, it became clear quickly that I hadn't initiated pygame and pygame.midi.

import pygame, pygame.midi, launchpad

pygame.init()
pygame.midi.init()
print "I've started"
LP = launchpad.Launchpad()
LP.Open()
print "I've worked"

Will run just fine.

Freezing with no error codes using non-standard library

1 Answers1