__init__.py

import os
import sys
import warnings 
import imp
import opcode # opcode is not a virtualenv module, so we can use it to find the stdlib
              # Important! To work on pypy, this must be a module that resides in the
              # lib-python/modified-x.y.z directory

dirname = os.path.dirname

distutils_path = os.path.join(os.path.dirname(opcode.__file__), 'distutils')
if os.path.normpath(distutils_path) == os.path.dirname(os.path.normpath(__file__)):
    warnings.warn(
        "The virtualenv distutils package at %s appears to be in the same location as the system distutils?")
else:
    __path__.insert(0, distutils_path)
    real_distutils = imp.load_module("_virtualenv_distutils", None, distutils_path, ('', '', imp.PKG_DIRECTORY))
    # Copy the relevant attributes
    try:
        __revision__ = real_distutils.__revision__
    except AttributeError:
        pass
    __version__ = real_distutils.__version__

from distutils import dist, sysconfig

try:
    basestring
except NameError:
    basestring = str

## patch build_ext (distutils doesn't know how to get the libs directory
## path on windows - it hardcodes the paths around the patched sys.prefix)

if sys.platform == 'win32':
    from distutils.command.build_ext import build_ext as old_build_ext
    class build_ext(old_build_ext):
        def finalize_options (self):
            if self.library_dirs is None:
                self.library_dirs = []
            elif isinstance(self.library_dirs, basestring):
                self.library_dirs = self.library_dirs.split(os.pathsep)
            
            self.library_dirs.insert(0, os.path.join(sys.real_prefix, "Libs"))
            old_build_ext.finalize_options(self)
            
    from distutils.command import build_ext as build_ext_module 
    build_ext_module.build_ext = build_ext

## distutils.dist patches:

old_find_config_files = dist.Distribution.find_config_files
def find_config_files(self):
    found = old_find_config_files(self)
    system_distutils = os.path.join(distutils_path, 'distutils.cfg')
    #if os.path.exists(system_distutils):
    #    found.insert(0, system_distutils)
        # What to call the per-user config file
    if os.name == 'posix':
        user_filename = ".pydistutils.cfg"
    else:
        user_filename = "pydistutils.cfg"
    user_filename = os.path.join(sys.prefix, user_filename)
    if os.path.isfile(user_filename):
        for item in list(found):
            if item.endswith('pydistutils.cfg'):
                found.remove(item)
        found.append(user_filename)
    return found
dist.Distribution.find_config_files = find_config_files

## distutils.sysconfig patches:

old_get_python_inc = sysconfig.get_python_inc
def sysconfig_get_python_inc(plat_specific=0, prefix=None):
    if prefix is None:
        prefix = sys.real_prefix
    return old_get_python_inc(plat_specific, prefix)
sysconfig_get_python_inc.__doc__ = old_get_python_inc.__doc__
sysconfig.get_python_inc = sysconfig_get_python_inc

old_get_python_lib = sysconfig.get_python_lib
def sysconfig_get_python_lib(plat_specific=0, standard_lib=0, prefix=None):
    if standard_lib and prefix is None:
        prefix = sys.real_prefix
    return old_get_python_lib(plat_specific, standard_lib, prefix)
sysconfig_get_python_lib.__doc__ = old_get_python_lib.__doc__
sysconfig.get_python_lib = sysconfig_get_python_lib

old_get_config_vars = sysconfig.get_config_vars
def sysconfig_get_config_vars(*args):
    real_vars = old_get_config_vars(*args)
    if sys.platform == 'win32':
        lib_dir = os.path.join(sys.real_prefix, "libs")
        if isinstance(real_vars, dict) and 'LIBDIR' not in real_vars:
            real_vars['LIBDIR'] = lib_dir # asked for all
        elif isinstance(real_vars, list) and 'LIBDIR' in args:
            real_vars = real_vars + [lib_dir] # asked for list
    return real_vars
sysconfig_get_config_vars.__doc__ = old_get_config_vars.__doc__
sysconfig.get_config_vars = sysconfig_get_config_vars