Multiple Versions of Python on Windows XP

"Martin v. Löwis" martin at
Tue Dec 2 08:05:06 CET 2008

> Could anyone please point me to documentation on the way the msi
> installer handles multiple versions eg. Python 2.5, 2.6 and 3.0?

I don't think that is documented anywhere.

> What changes are made to the registry?

For a complete list, see Tools/msi/ in the source tree.

> Is there some way to specify a default version in such a way that it can
> be changed as necessary?

What do you mean by "default version"?

There is the version that is associated with the .py/.pyc extensions
at any point in time; you can change these by re-running the respective
installers from add-and-remove-programs. In a well-managed installation,
only one Python installation would have the "Register Extensions"
feature selected; to then change the default, one would unselect the
feature in one version, and reselect it in a different. If only the
default installation procedure was ever used, re-running the installer
in "Repair" mode (from ARP) will also restore the extension

> PyScripter uses an option to select a version eg.
> C:\Program Files\PyScripter\PyScripter.exe --python26
> but I'm having some trouble with it when I attempt edit a python file
> from the Windows Explorer.

It would be good to be more specific with such statements: what troubles
specifically? If I play dumb, I'd say "of course - windows explorer
doesn't support editing Python files; you need a text editor".


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