How to find “import name” of any package in Python?

Question

I wonder if is there any reliable and consistant way to get a Python package\'s \"import name\" / namespace. For example;

Package; django-haystack

Answer 1

In principal, everything you need to get that information is in the setup.py that is supposed to be in every such package. That information would roughly be the union of the packages, py_modules, ext_package and ext_modules of the Distribution object. In fact, here's a little script that mocks out distutils.core.setup just for the purpose of getting that information.

import distutils.core
distutils.core._setup_stop_after = "config"
_real_setup = distutils.core.setup
def _fake_setup(*args, **kwargs):
    global dist
    dist = _real_setup(*args, **kwargs)

distutils.core.setup = _fake_setup

import sys
setup_file = sys.argv[1]
sys.argv[:] = sys.argv[1:]
import os.path
os.chdir(os.path.dirname(setup_file))

execfile(os.path.basename(setup_file))

cat = lambda *seq: sum((i for i in seq if i is not None), [])
pkgs = set(package.split('.')[0] for package
           in cat(dist.packages,
                  dist.py_modules,
                  [m.name for m in cat(dist.ext_modules)],
                  [m.name for m in cat(dist.ext_package)]))

print "\n".join(pkgs)

For many packages, this will work like a charm, but for a counterexample, see numpy, It breaks because numpy provides its own distutils, and I can see no obvious way around it.