Detect python package installation path from within setup.py

Question

After installation, I would like to make soft-links to some of the configuration & data files created by installation.

How can I determine the location of a new package's files installed from within the package's setup.py?

I initially hard-coded the path "/usr/local/lib/python2.7/dist-packages", but that broke when I tried using a virtual environment. (Created by virtualenv.)

I tried distutils.sysconfig.get_python_lib(), and that works inside the virtualenv. When installed on the real system, however, it returns "/usr/lib/python2.7/dist-packages" (Note the "local" directory isn't present.)

I've also tried site.getsitepackages():

Running a Python shell from the base environment:

import site

site.getusersitepackages()

'/home/sarah/.local/lib/python2.7/site-packages'

site.getsitepackages()

['/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages']

Running a Python shell from a virtual environment "testenv":

import site

site.getsitepackages()

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'module' object has no attribute 'getsitepackages'

I'm running "Python 2.7.3 (default, Aug 1 2012, 05:14:39)" with "[GCC 4.6.3] on linux2" on Ubuntu. I can probably cobble something together with try-except blocks, but it seems like there should be some variable set / returned by distutils / setuptools. (I'm agnostic about which branch to use, as long as it works.)

Thanks.

Answer 1

I haven't found the "correct" way of doing this, but I have found a couple tricks that seem almost-correct. One method only works on install; the other only works if the package is already installed.

For install, I use the object returned by setuptools.setup():

from setuptools import setup
s = setup([...])
installation_path = s.command_obj['install'].install_lib

(This only works during install since you need a valid Distribution object for those attributes to exist. AFAIK, the only way to get such an object is to run setup().)

On uninstall, I use the file attribute of the package, as suggested by @Zhenya above. The only catch is that when I run ./setup.py uninstall to get rid of package, I usually have directories ./package/, ./build, ./dist, and ./package.egg-info/. (The "uninstall" option is caught by my code without calling setup(). It runs a manually-created script to delete the package files.) These can redirect the python interpreter to some place other than the globally-accessible repository I'm trying to get rid of. Here's my hack to handle that:

import imp
import sys
from subprocess import Popen
from os import getcwd
Popen('rm -r build dist *.egg-info', shell=True).wait()
oldpath = sys.path
rundir = getcwd()
sys.path.remove(rundir)
mod = imp.find_module(PACKAGE)
p = imp.load_module(PACKAGE, mod[0], mod[1], mod[2])
sys.path = oldpath
installation_path = p.__file__

(This doesn't work during install since - I think - Python only inventories modules when it starts, so find_module() won't find the just-installed package unless you exit python and come back in.)

I've tested both install and uninstall on a bare environment and a virtual environment (from virtualenv 1.9.1). I'm running Ubuntu 12.04 LTS, Python 2.7.3, setuptools 0.6c11 (in the bare environment) and setuptools 0.7.4 (in virtualenv).