pyenv/pyenv-virtualenv

pyenv-virtualenv is a plugin for pyenv, the tool that lets you install and switch between multiple Python versions on a single computer. While pyenv handles which version of Python is active, pyenv-virtualenv goes a step further by managing isolated Python environments for individual projects. An isolated environment has its own copy of Python and its own set of installed packages, so changes made for one project cannot break another. To create a new environment, you run a single command and specify which Python version and what name you want. The environment is stored inside pyenv's own directory structure so it stays out of your project folder. You can list all your environments, switch to one by name, and delete one when you no longer need it. One convenient feature is auto-activation. If you add a short line to your shell configuration file, pyenv-virtualenv will automatically switch to the right environment whenever you navigate into a project folder that has a configuration file naming which environment to use. When you leave that folder, the environment is automatically deactivated. This means you generally do not have to remember to run any activate commands manually. The plugin works with the standard Python virtual environment tools for Python 3, with the older virtualenv package for Python 2 and older setups, and also with Anaconda and Miniconda conda environments. It detects which tool is available and uses the appropriate one. Installation on macOS through Homebrew is a single command. On other systems, it involves cloning the repository into pyenv's plugins directory and adding one line to your shell startup file. The plugin works on any Unix-like system including Linux and macOS.