Note: This article assumes you have python3.3+ and *NIX system installed. Some commands might not work on Windows out of the box (e.g. tree).
If you are a Python developer (beginner or advanced), you are bound to come across having to manage your dependencies in projects in an efficient manner in order to prevent version conflicts between different packages. And you might already know about some tools built in order to do exactly that. Over the years, I've used a number of those tools to manage my projects- virtualenv, virtualenvwrapper, pipenv, pyvenv, etc. But a few months ago, I discovered a fairly new tool that comes built-in with Python3 itself that can do almost everything that aforementioned tools can do and is much more elegant and easier to use than all of them, IMO.
The tool I'm talking about is the 'venv' module included in the stdlib of Python3.3+. You don't have to install anything on your machine to use it. Just navigate to your project folder and do:
$ python3 -m venv ./venv
Here, the second 'venv' is the name of the virtual environment we want to create.
Now, the project structure looks like:
$ tree -L 2 myproject/ myproject/ ... venv/ bin/ include/ lib/ pyvenv.cfg
To activate the virtual environment, just do:
$ source ./venv/bin/activate
Note how activating a virtualenv modifies your shell prompt with a little note showing the name of the virtualenv. This means that the Python interpreter, libraries and scripts installed into it are isolated from those installed in other virtual environments, and (by default) in the “system” Python, leaving global environment and other virtualenvs unaffected:
(venv) $ python3 -m pip install django (venv) $ python3 -m pip list Django (2.2.6) pip (9.0.1) pytz (2019.3) setuptools (39.0.1) sqlparse (0.3.0) ... (venv) $
To deactivate the virtual environment:
(venv) $ deactivate
To export your dependencies to an external file:
(venv) $ python3 -m pip freeze > requirements.txt
Deleting the virtual environment is as simple as deleting the 'venv' directory:
$ rm -rf ./venv
Make sure to deactivate the virtualenv before deleting it.
A quick aside: Before activating a virtual environment, the 'python' command maps to the system version of python interpreter:
$ which python3 /usr/bin/python3
But with an active virtual environment, the 'python' command maps to the interpreter binary inside the active virtualenv:
$ (venv) which python3 /home/$USERNAME/myproject/venv/bin/python3