When installing my python package, I want to be able to tell the user about various optional dependencies. Ideally I would also like to print out a message about these optional requirements and what each of them do.

I haven’t seen anything yet in the docs of either pip or docutils. Do tools these support optional dependencies?

These are called extras, here is how to use them in your setup.py.

The base support is in pkg_resources. You need to enable distribute in your setup.py. pip will also understand them:

pip install 'package[extras]'

Yes, at stated by @Tobu and explained here. In your setup.py file you can add a line like this:

extras_require = {
        'full': ['matplotlib', 'tensorflow', 'numpy', 'tikzplotlib']
    }

I have an example of this line here.

Now you can either install via PIP basic/vanilla package like pip install package_name or the package with all the optional dependencies like pip install package_name[full]

Where package_name is the name of your package and full is because we put “full” in the extras_require dictionary but it depends on what you put as a name.


If someone is interested in how to code a library that can work with or without a package I recommend this answer

Since PEP-621, this information is better placed in the pyproject.toml rather than setup.py. Here’s the relevant specification from PEP 621. Here’s an example snippet from a pyproject.toml (credit to @GwynBleidD):

[project.optional-dependencies]
test = [
  "pytest < 5.0.0",
  "pytest-cov[all]"
]
lint = [
  "black",
  "flake8"
]
ci = [
  "pytest < 5.0.0",
  "pytest-cov[all]",
  "black",
  "flake8"
]

A more complete example is found in the PEP