How to break in interactive mode on an exception to debug a Python script?

Question

I would like to debug a Python package, let say it is Sphinx.

when I do sphinx-build everything works utile a point I have an exception. Instead of the Traceback I would like to start an interactive session from there in which I can debug my code.

Is that possible?

For instance I am looking for something like:

$ python-debug sphinx-build arg args 
... 
...
Traceback (oops)
...
>>> print("Oh yeah, now we can play...")

Answer 1

Perhaps pdb might be of use to you. Simply invoke it like so where you want to break into the debugger:

import pdb; pdb.set_trace()

For more details please see the pdb documentation: https://docs.python.org/3/library/pdb.html

Edit: Perhaps more relevant to your question: pdb can be invoked on the command-line like so: python3 -m pdb myscript.py

Answer 2

I think this can help you to figure out where to place a debugger:

• Check the line number in the Traceback of the module.
• Then open the module in any of the text editor by going into the module location.
• Keep the debugger before that line.

If your are using python3.7 Then you can simply call this function breakpoint() or you can also do this by using import pdb; pdb.set_trace().