124: pip dependency resolver changes

pip is the package installer for Python.

Often, when you run pip, especially the first time in a new virtual environment, you will see something like:

WARNING: You are using pip version 20.1.1; however, version 20.2 is available.

You should consider upgrading via the 'python -m pip install --upgrade pip' command.

And you should. Because 20.2 has a new dependency resolver.

Get in the habit, until October, of replacing pip install with pip install --use-feature=2020-resolver.

This flag is new in the 20.2 release.

This new pip dependency resolver is the result of a lot of work.

Five of the people involved with this work are joining the show today: Bernard Tyers, Nicole Harris, Paul Moore, Pradyun Gedam, and Tzu-ping Chung.

We talk about:

pip dependency resolver changes

user experience research and testing

crafting good error messages

efforts to improve the test suite

testing pip with pytest

some of the difficulties with testing pip

working with a team on a large project

working with a large code base

bringing new developers into a large project

Special Guests: Bernard Tyers, Nicole Harris, Paul Moore, Pradyun Gedam, and Tzu-ping Chung. Sponsored By:PyCharm Professional: Try PyCharm Pro for 4 months and learn how PyCharm will save you time. Promo Code: TESTANDCODE22Links:Changelog — pip 20.2 documentation — Including --use-feature=2020-resolverpypa/pip: The Python package installer — github repotesting pip - documentationpip - The Python Package Installer — pip 20.2 documentationChanges to the pip dependency resolver in 20.2 — Changes to the pip dependency resolver in 20.2