Multiple versions of python

Dave Angel davea at dejaviewphoto.com
Tue Jul 21 16:19:42 CEST 2009


ChrisW wrote:
> Hi,
>
> I have installed 2 versions of python on my Windows XP computer - I
> originally had 3.0.1, but then found that the MySQL module only
> supported 2.*, so I've now installed that.  I have found that if I
> change the Windows Environment Variable path, then I can change the
> version of python called when I type 'python' into a command line.
> However, I'd like to be able to choose which version I use.  I know
> that if I change C:\Python26\python.exe to
> C:\Python26\python2.exe and C:\Python30\python.exe to C:
> \Python26\python3.exe, then typing 'python2' or 'python3' will invoke
> the correct interpreter.  However, is it safe just to rename the
> executable files? Is there a more elegant way to achieve the same
> task?
>
> Thanks,
> Chris
>
>   
The elegant way is to have a batch directory on your PATH ( I use  
m:\t\bat )  and put your *.bat files there.   I do NOT put any python 
installations on the PATH.

For example, I have a batch file called:     m:\t\bat\python26.bat

c:\progfiles\python26\python.exe %*

The %* syntax means pass all arguments through to the program.

Once it all works, you can add an "@" in front of the c:   in order to 
suppress echoing the command.  At that point, it'll look and work the 
same way as what you did, but without modifying anything in the install 
directory.    (You may want  python26.bat, pythonw26.bat, python31.bat 
and pythonw31.bat)



The other thing you may want to do in a batch file is to change the file 
associations so that you can run the .py file directly, without typing 
"python" or "pythonw" in front of it.

The relevant Windows commands are:     assoc and ftype      And on a 
related note, you may want to edit the PATHEXT environment variable, to 
add .PY and .PYW





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