The calver package is a setuptools extension for automatically defining your Python package version as a calendar version.

First, ensure calver is present during the project's build step by specifying it as one of the build requirements:

pyproject.toml:

[build-system]
requires = ["setuptools>=42", "calver"]

To enable generating the version automatically based on the date, add the following to setup.py:

setup.py:

from setuptools import setup

setup(
    ...
    use_calver=True,
    setup_requires=['calver'],
    ...
)

You can test that it is working with:

$ python setup.py --version
2020.6.16

By default, when setting use_calver=True, it uses the following to generate the version string:

>>> import datetime
>>> datetime.datetime.now().strftime("%Y.%m.%d")
2020.6.16

You can override the format string by passing it instead of True:

setup.py:

from setuptools import setup

setup(
    ...
    use_calver="%Y.%m.%d.%H.%M",
    setup_requires=['calver'],
    ...
)

You can override this entirely by passing a callable instead, which will be called with no arguments at build time:

setup.py:

import datetime
from setuptools import setup

def long_now_version():
    now = datetime.datetime.now()
    return now.strftime("%Y").zfill(5) + "." + now.strftime("%m.%d")

setup(
    ...
    use_calver=long_now_version,
    setup_requires=['calver'],
    ...
)