Tagging installed Python libraries

Generating TAGS for the project I’m working on with the addition of an installed library — Twisted for example — can be a pain:

$ python
>>> import twisted
>>> twisted.__file__
'/usr/lib/python2.6/dist-packages/twisted/__init__.pyc'
$ etags -R src /usr/lib/python2.6/dist-packages/twisted

I got bored of that.

Enter pyctags to take the pain away:

$ pyctags -e -R src py:twisted

It’s a pretty simple script:

#!/usr/bin/env python

from imp import find_module
from os import execvp
from os.path import dirname
from sys import argv, stderr


def expand(arg):
    if arg.startswith("py:"):
        module_name = arg[3:].replace(".", "/")
        try:
            return find_module(module_name)[1]
        except ImportError:
            stderr.write("Could not expand %r.\\n" % module_name)
            return arg
    else:
        return arg


if __name__ == '__main__':
    args = ["ctags"]
    args.extend(expand(arg) for arg in argv[1:])
    execvp("ctags", args)