Virtualenv & Pip tips

Virtualenvs are not movable

You can't create a virtualenv on one machine, move or copy the mysite_env directory somewhere else and use it there. You can't even copy it to a different directory on the same machine (there's work in progress to make that possible, but it isn't right now).

Virtualenvs should be treated as disposable. The point of keeping requirements.txt up to date is that you shouldn't even care if your virtualenv is deleted (or if you're deploying on a new machine), because all you have to do to recreate it is:

virtualenv mysite_env
source mysite_env/bin/activate
pip install -r mysite/requirements.txt

and you're back in business.

Virtualenv on Mac OSX requires Xcode

Apparently for virtualenv to work on Mac OSX you have to have Apple Developer Tools (aka Xcode) installed. This is only relevant for those of you developing locally on your own Macs.