Question

I’ve got various versions of python installed on my Mac using Macports. When I’ve selected python 2.7 via $ port select python python27, virtualenvwrapper works perfectly.

But if I select another version of python, i.e. 2.6, virtualenvwrapper generates an error message: ImportError: No module named virtualenvwrapper.hook_loader

I checked my .profile and it’s setting VIRTUALENVWRAPPER_PYTHON to /opt/local/bin/python, so it seems to me virtualenvwrapper should work regardless of which python I’ve selected.

Any idea what would cause virtualenvwrapper to generate a .hook_loader error when I switch python versions?

Answer 1

I know this is pretty much solved in your comments, but it’s mac only,

and even more I think the correct way should be to set VIRTUALENVWRAPPER_PYTHON to the real python you are using on the command line.

To be sure you can do which python.

Actually, you can even do:

export VIRTUALENVWRAPPER_PYTHON=`which python`

On linux I do this in my .bashrc, so all in all, assuming you installed virtualenv and created your first “virtual environment” virtualenv (how original)

. virtualenv/bin/activate
export WORKON_HOME=$HOME/.virtualenvs # or whatever else you want
export VIRTUALENVWRAPPER_PYTHON=`which python`
export PROJECT_HOME=SOMETHING
source $HOME/virtualenv/bin/virtualenvwrapper.sh # or wherever else you got that installed

(and by the way, you wrote:

I checked my .profile and it’s setting VIRTUALENVWRAPPER_PYTHON to /opt/local/bin/python, so it seems to me virtualenvwrapper should work regardless of which python I’ve selected

which is actually the opposite – virtualenv relies on using the correct python (and the packages that go with it) so it’s very important to set the python path accordingly.

Even running a py file with a “#!/bin/python” might bring trouble once you are virtualenved!