Separate Windows versions of Python

OldGrantonian OldGrantonian at
Wed May 6 18:24:56 CEST 2009

Many thanks for the very detailed answer :)

I will go ahead right now and implement all your suggestions.

On May 6, 4:35 pm, Scott David Daniels <Scott.Dani... at Acm.Org> wrote:
> OldGrantonian wrote:
> > I use Windows Vista Home Premium. I have Python 2.6 currently
> > installed. I'm not a techy.
> > I want to use "virtualenv". When I try to install the latest version
> > of virtualenv for Windows, I get the message that Python 2.5 is not
> > found.
> > How do I install Python 2.5 (or anything else except 2.6) so that I
> > use the correct version of Python at the correct time.
> > For example, do I need to edit the "path" variable each time that I
> > want to change versions from 2.5 to 2.6?
> On windows, major versions (..., 2.5, 2.6, 2.7, ...., 3.0, 3.1,  ...)
> can coexist quite successfully.  Find and run an installer for the
> latest version  of 2.5 (2.5.4, I believe) on the Python download page.
> That will make 2.5 your default Python.  To switch the easiest way
> (for you) is uninstall the version of python you want to be the
> default, then install it again (making it the last one installed).
> This suggests keeping installer binaries for all version you are
> using.  Note that the this uninstall-reinstall should not affect
> you loaded Python packages that you have installed separately.
> To simply run a python program with a different python (but not
> change the default), open a command window (run program / cmd),
> sometimes called a "terminal window" and use command:
>      C:\> C:\Python24\python  # command line version
> or
>      C:\> C:\Python24\pythonw program.pyw  # gui verson
> You can also change shortcuts to refer to specific Python versions.
> Of course, the different Python versions should also be available
> on your start menu.
> However, Starting with Python 2.6, if you want user-specific
> installation, you can also create and put things in (for example),
>      C:\Documents and Settings\USER\Application Data\
>                              Python\Python26\site-packages
> where you replace USER with the user name in question.
> If you are not planning to do a lot of switching, that might be
> enough for you.  The base directory is also called %APPDATA% on
> a command line or via os.path.expandvars.  Once you have created
> this site-packages directory, Python 2.6 and later will use it to
> find .pth, .py, .pyw, and .pyd files (as well as .pyc and .pyo
> files).  You may find changing your personal site-packages directory
> (and/or a .pth therein that you manipulate) will address the issues
> that you are planning to solve with virtualenv.
> Sorry for the long-winded answer.
> --Scott David Daniels
> Scott.Dani... at Acm.Org
> in addition to the common site-packages directory on

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