Create hard links / junctions to the system-installed packages in a given virtualenv ("site-packages") directory.

redirect-package.py

#!/usr/bin/env python
# 
# Create hard links / junctions to the system-installed packages in 
# a given virtualenv ("site-packages") directory.
# 
# 
# Background
# ==========
# 
# Some libraries such as wxPython do not support pip installation yet. 
# It makes hard for develpers to develop Python softwares under the 
# virtualenv environment. This script may help you with such issues.
# 
# 
# Example
# =======
# 
#   C:\work>virtualenv venv
#       ...
#   C:\work>redirect-package.py venv wx
#       ...
#   C:\work>venv\Scripts\activate.bat
#   (venv) C:\work>python
#       ...
#   >>> import wx
#   >>>
# 
# (You can import system-installed wxPython in the virtualenv interpreter.)
# 
# 
# Requirements
# ============
# 
# * Python 2.7 or later
# 
#   NOTE: It works on POSIX platforms as well as on Windows now.
# 
# 
# License
# =======
# 
# This program is in the public domain.


from __future__ import (absolute_import,
                        division,
                        print_function,
                        unicode_literals)
import argparse
import imp
import os
import subprocess


def virtualenv_sys_version(dir_venv):

    if os.name == 'nt':
        python = os.path.join(dir_venv, 'Scripts', 'python.exe')
    else:
        python = os.path.join(dir_venv, 'bin', 'python')
    output = subprocess.check_output(
        [python, '-c', 'import sys; print(sys.version)']
    )   # get 'X.Y.Z (...)'
    return output


def virtualenv_site_packages_dir(dir_venv):

    if os.name == 'nt':
        paths = [dir_venv, 'Lib', 'site-packages']
    else:
        sys_version = virtualenv_sys_version(dir_venv)
        pythonXY = 'python%s.%s' % tuple(sys_version.split('.')[:2])
        paths = [dir_venv, 'lib', pythonXY, 'site-packages']
    site_packages_dir = os.path.join(*paths)
    return site_packages_dir


def create_module_link(source, link_name):

    if os.name == 'nt':
        os.system('mklink /h "%s" "%s"' % (link_name, source))
    elif os.name == 'posix':
        os.link(source, link_name)


def create_package_link(source, link_name):

    if os.name == 'nt':
        os.system('mklink /j "%s" "%s"' % (link_name, source))
    elif os.name == 'posix':
        os.symlink(source, link_name)


def main():    

    parser = argparse.ArgumentParser(
        description='Redirect packages to virtualenv'
    )
    parser.add_argument('venv')
    parser.add_argument('packages', nargs='+')
    args = parser.parse_args()

    dest = virtualenv_site_packages_dir(args.venv)
    for package in args.packages:
        fileobj, dirname, desc = imp.find_module(package)
        if fileobj:
            filename = fileobj.name
            link_name = os.path.join(dest, os.path.basename(filename))
            create_module_link(filename, link_name)
        else:
            link_name = os.path.join(dest, os.path.basename(dirname))
            create_package_link(dirname, link_name)


if __name__ == '__main__':
    main()