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So I am attempting to make a module that, when imported, will cause any exception to drop into pdb. I'm thinking it will look something like this:

#file A.py import pdbOnException a = 1/0 print a #file pdbOnException import sys, pdb magic_object = # do magic stuff to get an object that, when called, does what I want :D try: magic_object() except: tb = sys.exc_info()[2] pdb.post_mortem(tb)

Hopefully it is fairly obvious what I am trying to do. I am trying to make it so that any module that imports this will have its unhandled exceptions go to pdb.

Edit: I thought I should add what I want to use this for, and see if you know anything about that. I am planning on adding the module to eclipse's "Forced Builtins" so that eclipse will have this functionality (it is SORELY needed) Can anyone help me out?

Edit2: after playing with eclipse a bunch, it looks like there is NO WAY to force eclipse to run a set of code (i.e. like PYTHONSTARTUP) prior to running any code. Which sucks. Therefore I think I will just go for the decorator.

If you still have an idea of how to do this by just importing modules, I am all ears. It could be added to the IDLE startup script.

Update: I just got something working using decorators, but the user has to call it for their main function (which isn't the end of the world... but I would like even more functionality). Here it is:

def pdb_on_exception(function): def returnfunction(*args, **kwargs): try: return function(*args, **kwargs) except Exception as E: traceback.print_tb(sys.exc_info()[2]) print E tb = sys.exc_info()[2] pdb.post_mortem(tb) return returnfunction

This will drop you into pdb if there is an unhandled exception on the function that is being decorated. Which is cool but still not what I want :D

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    Similar to your decorator, you could also devise a context manager that does this. I don't see any way to make it reach out and affect the importing module though - you would need to modify Eclipse to wrap the execution of all imported modules with your new context manager. Commented Apr 1, 2011 at 18:00
  • I wish I knew how to modify eclipse to do this... I'm doing another update with more of my attempts. Commented Apr 1, 2011 at 18:45

1 Answer 1

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That's pretty trivial, you just hook into sys.excepthook:

fullofeels.py:

import sys, pdb def except_hook(exctype, value, traceback): if previous_except_hook: previous_except_hook(exctype, value, traceback) pdb.post_mortem(traceback) previous_except_hook = sys.excepthook sys.excepthook = except_hook

Usage:

Normally we just get a traceback:

>>> 1/0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: integer division or modulo by zero

But import fullofeels, and we fall into pdb:

>>> import fullofeels >>> 1/0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: integer division or modulo by zero > <stdin>(1)<module>() (Pdb)

Tada!

I have no idea how many eels are in that hovercraft, but for simple cases it works.

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4 Comments

It's only easy if you know about excepthook! Thanks a ton! (I can't upvote yet, but I WILL as soon as I can)
Oh, very nice - I didn't even think about excepthook, since I was looking at it from an executing-a-script point of view, rather than an interactive-prompt one.
@Garrett: since you asked the question, you should have an "Accept Answer" button that you can click.
Since I couldn't vote before, it didn't pop up, but it just did when I voted. Answer accepted, thanks :D

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