Python home directory in Windows / Problem with multiple versions

Question

I'm using Python 3 for developing and CollabNet Subversion Edge as versioning software. Subversion Edge comes with a little program called ViewVC which is written in Python 2, which is also directly bundled with it. There is a system environment variable called PYTHONHOME.

• If it is set to the Python 2 distribution from Subversion Edge, my Python 3 won't start (not even IDLE), instead giving a runtime error messagebox.
• If it is set to Python 3, ViewVC doesn't work.

Is there a way to make both work at the same time?

Answer 1

You shouldn't need to set PYTHONHOME at all. Python uses it (if set) to locate its installation. Typically, it should be able to locate it without this variable, as well: by looking at the path name of the python executable, and, failing that, by looking into the registry.

Answer 2

Write a .bat or cmd file that saves the value of the PYTHONHOME env var, invokes ViewVC and wait for it to finish, then restores PYTHONHOME to the saved value.

Answer 3

Have you considered changing the Subversion Edge services to run as a specific user account, and then move the PYTHONHOME environment variable to a user-level variable for that account only? As opposed to a system-wide variable? It seems like it should work.

BTW, the PYTHONHOME variable is added for mod_python to work properly (which is what serves ViewVC). If you can find another way to get mod_python to work, then you could try that.