Monday, November 30, 2020

Releasing pip 20.3, featuring new dependency resolver

On behalf of the Python Packaging Authority and the pip team, I am pleased to announce that we have just released pip 20.3, a new version of pip. You can install it by running python -m pip install --upgrade pip.

This is an important and disruptive release -- we explained why in a blog post last year. We've even made a video about it.


  • DISRUPTION: Switch to the new dependency resolver by default. Watch out for changes in handling editable installs, constraints files, and more:

  • DEPRECATION: Deprecate support for Python 3.5 (to be removed in pip 21.0).

  • DEPRECATION: pip freeze will stop filtering the pip, setuptools, distribute and wheel packages from pip freeze output in a future version. To keep the previous behavior, users should use the new --exclude option.

  • Substantial improvements in new resolver for performance, output and error messages, avoiding infinite loops, and support for constraints files.

  • Support for PEP 600: Future manylinux Platform Tags for Portable Linux Built Distributions.

  • Documentation improvements: Resolver migration guide, quickstart guide, and new documentation theme.

  • Add support for MacOS Big Sur compatibility tags.

The new resolver is now on by default for Python 3 users. It is significantly stricter and more consistent when it receives incompatible instructions, and reduces support for certain kinds of constraints files, so some workarounds and workflows may break. Please see our guide on how to test and migrate, and how to report issues. You can use the deprecated (old) resolver, using the flag --use-deprecated=legacy-resolver, until we remove it in the pip 21.0 release in January 2021.

You can find more details (including deprecations and removals) in the changelog.

Coming soon: end of Python 2.7 support

We aim to release pip 21.0 in January 2021, per our release cadence. At that time, pip will stop supporting Python 2.7 and will therefore stop supporting Python 2 entirely.
When users use pip 20.3 in a Python 2 environment, the old dependency resolver is still the default.

For more info or to contribute:

We run this project as transparently as possible, so you can:

Thank you

Thanks to our contractors on this project: Simply Secure (specifically Georgia Bullen, Bernard Tyers, Nicole Harris, Ngọc Triệu, and Karissa McKelvey), Changeset Consulting (Sumana Harihareswara), Atos (Paul F. Moore), Tzu-ping Chung, Pradyun Gedam, and Ilan Schnell. Thanks also to Ee Durbin at the Python Software Foundation for liaising with the project.
This award continues our relationship with Mozilla, which supported Python packaging tools with a Mozilla Open Source Support Award in 2017 for Warehouse. Thank you, Mozilla! (MOSS has a number of types of awards, which are open to different sorts of open source/free software projects. If your project will seek financial support in 2021, do check the MOSS website to see if you qualify.)

This is new funding from the Chan Zuckerberg Initiative. This project is being made possible in part by a grant from the Chan Zuckerberg Initiative DAF, an advised fund of Silicon Valley Community Foundation. Thank you, CZI! (If your free software/open source project is seeking funding and is used by researchers, check the Joint Roadmap for Open Science Tools Rapid Response Fund and consider applying.)
The funding for pip's overhaul will end at the end of 2020; if your organization wants to help continue improvements in Python packaging, please join the sponsorship program.

As with all pip releases, a significant amount of the work was contributed by pip's user community. Huge thanks to all who have contributed, whether through code, documentation, issue reports and/or discussion. Your help keeps pip improving, and is hugely appreciated. Thank you to the pip and PyPA maintainers, to the PSF and the Packaging WG, and to all the contributors and volunteers who work on or use Python packaging tools.
-Sumana Harihareswara, pip project manager

Wednesday, November 4, 2020

Python 3.10.0a2 is now available for testing

The engines of the secret release manager machine have finished producing a new pre-release. Go get it here: 

This is an early developer preview of Python 3.10

Major new features of the 3.10 series, compared to 3.9

Python 3.10 is still in development. This releasee, 3.10.0a2 is the second of six planned alpha releases.
Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.
During the alpha phase, features may be added up until the start of the beta phase (2021-05-03) and, if necessary, may be modified or deleted up until the release candidate phase (2021-10-04). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.10 are still being planned and written. Among the new major
new features and changes so far:

  • PEP 623 – Remove wstr from Unicode
  • PEP 604 – Allow writing union types as X | Y
  • PEP 612 – Parameter Specification Variables
  • PEP 626 – Precise line numbers for debugging and other tools.
  • bpo-38605from __future__ import annotations (PEP 563) is now the default.
  • (Hey, fellow core developer, if a feature you find important is missing from this list, let Pablo know.)

The next pre-release of Python 3.10 will be 3.10.0a3, currently scheduled for 2020-12-07.

More resources

And now for something completely different

The cardinality (the number of elements) of infinite sets can be one of the most surprising results of set theory. For example, there are the same amount of even natural numbers than natural numbers (which can be even or odd). There is also the same amount of rational numbers than natural numbers. But on the other hand, there are more real numbers between 0 and 1 than natural numbers! All these sets have infinite cardinality but turn out that some of these infinities are bigger than others. These infinite cardinalities normally are represented using aleph numbers. Infinite sets are strange beasts indeed.

Your friendly release team,
Ned Deily @nad
Steve Dower @steve.dower
Pablo Galindo Salgado @pablogsal