multiple Python 2.7 Windows installations

Mark Hammond mhammond at
Wed Apr 20 06:14:52 CEST 2011

On 20/04/2011 12:40 AM, Eric Frederich wrote:
> Hello,
> I am trying to get an installer built with distutils to recognize
> multiple installations.
> The installer currently finds my installation at C:\Python27
> I have a custom Python27 built myself with Visual Studio sitting
> somewhere else, say C:\MyPython27.
> I looked at PC/bdist_wininst/install.c in the GetPythonVersions
> routine and see that it is searching Software\Python\PythonCore.
> So, I assume I need to get my Python installation listed in the registry.
> I am unfamiliar with the Windows Registry
> I tried to create another 2.7 key but regedit wouldn't let me.
> So, if I can only have one 2.7 key, it would seem that the routine
> GetPythonVersions will only ever get 1 version of 2.7.
> Does this mean that it is unsupported to have more than one Python 2.7
> installation on Windows?

Yes, it does.  Only 1 such installed version is considered "the" version 
- although you could just have something temporarily adjust the 
InstallPath entry in the registry.

> Again, that GetPythonVersions routine looks pretty alien to me.... so
> I may be wrong.

You have it right - although the idea is that if you have a "portable" 
package to install (ie, no C extension modules), that routine will offer 
to install it into *any* Python version.



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