Debugging python programs in emacs

Question

Type M-x cd to change directory to the location of the program you wish to debug. Type M-x pdb. You'll be prompted with Run pdb (like this): pdb. Enter the name of the program (e.g. test.py).

At the (Pdb) prompt, type help to learn about how to use pdb.

Alternatively, you can put

import pdb 
pdb.set_trace()

right inside your program (e.g. test.py). Now type M-x shell to get a shell prompt. When you run your program, you'll be dumped into pdb at the point where pdb.set_trace() is executed.

For me, I needed to replace the default "pdb" with

python -m pdb myscript.py

The realgud package (available from MELPA) supports PDB (among a gazillion other debuggers), and has a host of neat features that Emac's PDB doesn't have.

The one I like best is the shortkeys mode. Once you start debugging a program, you can press n, s, c etc. right in the source window, instead of having to type these commands in the PDB buffer. It also supports Visual-Studio style keybindings with function keys (f10, f11, f5, etc).

After installing RealGUD, you need to run M-x load-feature realgud to load it, and you can start pdb with M-x realgud:pdb.