How to use Python's "easy_install" on Windows ... it's not so easy

Question

After installing Python 2.7 on Windows XP, then manually setting the %PATH% to python.exe (why won't the python installer do this?), then installing setuptools 0.6c11 (why doesn't the python installer do this?), then manually setting the %PATH% to easy_install.exe (why doesn't the installer do this?), I finally tried to install a python package with easy_install, but easy_install failed when it couldn't install the pywin32 package, which is a dependency. How can I make easy_install work properly on Windows XP? The failure follows:

C:\>easy_install winpexpect
Searching for winpexpect
Best match: winpexpect 1.4
Processing winpexpect-1.4-py2.7.egg
winpexpect 1.4 is already the active version in easy-install.pth

Using c:\python27\lib\site-packages\winpexpect-1.4-py2.7.egg
Processing dependencies for winpexpect
Searching for pywin32>=214
Reading http://pypi.python.org/simple/pywin32/
Reading http://sf.net/projects/pywin32
Reading http://sourceforge.net/project/showfiles.php?group_id=78018
No local packages or download links found for pywin32>=214
Best match: None
Traceback (most recent call last):
  File "C:\python27\scripts\easy_install-script.py", line 8, in 
    load_entry_point('setuptools==0.6c11', 'console_scripts', 'easy_install')()
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 1712, in main
    with_ei_usage(lambda:
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 1700, in with_ei_usage
    return f()
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 1716, in 
    distclass=DistributionWithoutHelpCommands, **kw
  File "C:\python27\lib\distutils\core.py", line 152, in setup
    dist.run_commands()
  File "C:\python27\lib\distutils\dist.py", line 953, in run_commands
    self.run_command(cmd)
  File "C:\python27\lib\distutils\dist.py", line 972, in run_command
    cmd_obj.run()
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 211, in run
    self.easy_install(spec, not self.no_deps)
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 446, in easy_install
    return self.install_item(spec, dist.location, tmpdir, deps)
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 481, in install_item
    self.process_distribution(spec, dists[0], deps, "Using")
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 519, in process_distribution
    [requirement], self.local_index, self.easy_install
  File "C:\python27\lib\site-packages\pkg_resources.py", line 563, in resolve
    dist = best[req.key] = env.best_match(req, self, installer)
  File "C:\python27\lib\site-packages\pkg_resources.py", line 799, in best_match
    return self.obtain(req, installer) # try and download/install
  File "C:\python27\lib\site-packages\pkg_resources.py", line 811, in obtain
    return installer(requirement)
  File "C:\python27\lib\site-packages\setuptools\command\easy_install.py", line 434, in easy_install
    self.local_index
  File "C:\python27\lib\site-packages\setuptools\package_index.py", line 475, in fetch_distribution
    return dist.clone(location=self.download(dist.location, tmpdir))
AttributeError: 'NoneType' object has no attribute 'clone'

To answer one question above, the Python installer won't modify your PATH variable because 1) it can't modify the PATH correctly on uninstall, and 2) you can have multiple Python versions on the same system, and this can cause unexpected behavior. See bugs.python.org/issue3561 — Brandon
As to why setuptools isn't part of the standard Python distribution, see faassen.n--tree.net/blog/view/weblog/2009/11/09/0 — Brandon
Brandon: thanks for your input. I know this is a somewhat tangential discussion, I have to say that when you have a hard decision to make ,such as whether to set the PATH or which package manager to preload with the distribution, the best thing to do is to give the user the OPTION to do what they probably want anyway. Example: "Add python to path? If you don't know what this means, select yes. [yes] [no]" ... "Install setuptools and set their path? If you don't know what this means, select yes. [yes] [no]". This is not a perfect solution, but it beats the hell out of sending newbies to google. — Nick

Brandon Brandon · Accepted Answer · 2010-10-25T16:10:37

One problem is that easy_install is set up to download and install .egg files or source distributions (contained within .tgz, .tar, .tar.gz, .tar.bz2, or .zip files). It doesn't know how to deal with the PyWin32 extensions because they are put within a separate installer executable. You will need to download the appropriate PyWin32 installer file (for Python 2.7) and run it yourself. When you run easy_install again (provided you have it installed right, like in Sergio's instructions), you should see that your winpexpect package has been installed correctly.

Since it's Windows and open source we are talking about, it can often be a messy combination of install methods to get things working properly. However, easy_install is still better than hand-editing configuration files, for sure.

How to use Python's "easy_install" on Windows ... it's not so easy

6 Answers