There must be hundreds of alternatives for using Python virtualenv in a simple and clean way, but the following is by far the one that I find most intuitive and easy to set up. The idea is simple. Each time you want to use a virtualenv in a project, you need to:

1. Add to your folder a new two files:
   • 1.1. A .python-version file with the Python version you need.
   • 1.2. A .python-virtualenv file with the name of the virtual environment.
2. Switch to the project folder.
3. Done. Your environment is loaded for that particular project, and you are ready to go.

For this, you will need to have pyenv and virtualenv installed in your development environment. Once that’s done, you need to source the following bash script. Note that the .python-version is a pyenv requirement and all details related to its definition and usage can be found [here].

This script works roughly as follows. First, it verifies the .python-version file which only contains the version of python you want to use. For example,

$ cat .python-version
3.7.2

If pyenv is available and supports the python version you are intending to use, a virtualenv is then created pointing to a .python folder within your projects home directory. The name of the virtualenv is defined in the .python-virtualenv file, for example,

$ cat .python-virtualenv
my_python_project

If you want to use a given python version, the script will verify if it’s available within pyenv. If not, then it will prompt instructions on how to install it. Also, there are a few optimizations you might want to make to the strategy (e.g. using only one config file, prompting more options, etc.) but this should be enough to get you ready and set up to use Python virtual environments in an easy way.

You can use the script above in your development environment by sourcing it from your favorite bash/tcsh/zsh/other “autoloading” script (e.g. your .bash_profile or your .zshrc, etc.). Save the file locally (e.g. in ~/.development_scripts/python_env_load.sh). Finally, I strongly suggest adding the following environment variables to your system so you make sure that anything you install is within a vitualenv. Both the source of the script and the pip environment variables together would look like this:

Special thanks to @rzilleruelo for coming up with the first versions of this virtualenv+pyenv bash script.