Simplifying common operations – using the virtualenvwrapper tool

Note

This will also install the virtualenv package as well in case it is not already present.

Note

Adding an entire virtual environment to version control might seem like a good idea, but things are never as simple as they seem. The moment someone running a slightly (or completely) different operating system decides to download your project, which includes a full virtualenv folder that may contain packages with C modules that were compiled against your own architecture, they're going to have a hard time getting things to work.

Instead, a common pattern that is supported by pip and used by many developers is to freeze the current state of the installed packages in a virtual environment and save this to a requirements.txt file:

(testing) $ pip freeze > requirements.txt

This file may then be added to a version control system (VCS). As the intent of the file is to declare which dependencies are required for the application, and not provide them or indicate how they should be constructed, users of your project are then free to obtain the required packages in any way they so choose. Generally, they will install them via pip, which can handle a requirements file just fine:

(testing) $ pip install –r  requirements.txt

Note

If you are using a shell other than Bash or ZSH, this environment tag may or may not appear. The way in which this works is that the script that is used to activate the virtual environment also modifies your current prompt string (the PS1 environment variable) so that it indicates the currently active virtualenv. As a result, there is a chance that this may not work if you're using a very special or non-standard shell configuration.