Implement --pdb in a python cli

2022-01-13

Waylon Walker

Adding a --pdb flag to your applications can make them much easier for those using it to debug your application, especially if your applicatoin is a cli application where the user has much fewer options to start this for themselves. To add a pdb flag --pdb to your applications you will need to wrap your function call in a try/except, and start a post_mortem debugger. I give credit to this stack overflow post for helping me figure this out.

import pdb, traceback, sys


def bombs():
    a = []
    print(a[0])


if __name__ == "__main__":
    if "--pdb" in sys.argv:
        try:
            bombs()
        except:
            extype, value, tb = sys.exc_info()
            traceback.print_exc()
            pdb.post_mortem(tb)
    else:
        bombs()

Using --pdb

python yourfile.py --pdb