If you’ve worked with virtualenvs for Python before for development/testing, then you may have hit cases where you really wanted multiple versions of Python installed in your virtualenv. Which, you may actually have working, because virtualenv, in theory, supports this. In fact, you’re supposed to be able to do:
$ virtualenv -p python2.6 my-env $ virtualenv -p python2.7 my-env
That’d be great, if it always worked. It doesn’t. When your virtualenv gets built, bin/python may end up being a link to bin/python2.7 (or what have you), or it may be the contents instead of a link. Subsequent installs may end up overwriting binaries, producing a python2.6 and python2.7that are both Python 2.7.
Oh and it gets worse. On Mac, with a standard Python install, these binaries actually end up invoking ../.Python, a symlink pointing to the system Python. This link is not versioned. So much for multiple Python versions in one virtualenv on the Mac.
We fixed this. Now you can run a single command to get a working environment going, without messing with things or running into problems on the Mac. This is virtualenv-multiver.
Now, setting up an environment is as simple as:
$ pip install virtualenv-multiver $ virtualenv-multiver my-env 2.6 2.7
Couldn’t be easier. This works both for new environments and existing ones.
This is a beta, so there may be some issues here or there. If this is useful to you, give it a try and let us know!