Emacs: methods for debugging python
- by Tom Willis
I use emacs for all my code edit needs. Typically, I will use M-x compile to run my test runner which I would say gets me about 70% of what I need to do to keep the code on track however lately I've been wondering how it might be possible to use M-x pdb on occasions where it would be nice to hit a breakpoint and inspect things.
In my googling I've found some things that suggest that this is useful/possible. However I have not managed to get it working in a way that I fully understand.
I don't know if it's the combination of buildout + appengine that might be making it more difficult but when I try to do something like
M-x pdb
Run pdb (like this): /Users/twillis/projects/hydrant/bin/python /Users/twillis/bin/pdb /Users/twillis/projects/hydrant/bin/devappserver /Users/twillis/projects/hydrant/parts/hydrant-app/
Where .../bin/python is the interpreter buildout makes with the path set for all the eggs.
~/bin/pdb is a simple script to call into pdb.main using the current python interpreter
HellooKitty:hydrant twillis$ cat ~/bin/pdb
#! /usr/bin/env python
if __name__ == "__main__":
import sys
sys.version_info
import pdb
pdb.main()
HellooKitty:hydrant twillis$
.../bin/devappserver is the dev_appserver script that the buildout recipe makes for gae project and .../parts/hydrant-app is the path to the app.yaml
I am first presented with a prompt
Current directory is /Users/twillis/bin/
C-c C-f
Nothing happens but
HellooKitty:hydrant twillis$ ps aux | grep pdb
twillis 469 100.0 1.6 168488 67188 s002 Rs+ 1:03PM 0:52.19 /usr/local/bin/python2.5 /Users/twillis/projects/hydrant/bin/python /Users/twillis/bin/pdb /Users/twillis/projects/hydrant/bin/devappserver /Users/twillis/projects/hydrant/parts/hydrant-app/
twillis 477 0.0 0.0 2435120 420 s000 R+ 1:05PM 0:00.00 grep pdb
HellooKitty:hydrant twillis$
something is happening
C-x [space]
will report that a breakpoint has been set. But I can't manage to get get things going.
It feels like I am missing something obvious here. Am I?
So, is interactive debugging in emacs worthwhile? is interactive debugging a google appengine app possible? Any suggestions on how I might get this working?
