Python 3.12.0 release candidate 1 released

Core Development
1

It’s finally happening! Python 3.12.0 rc1 is here! As a reminder, until the final release of 3.12.0, the 3.12 branch is set up so that the Release Manager (me) has to merge the changes. Please add me (@Yhg1s on GitHub) to any changes you think should go into 3.12.

This is the first release candidate of Python 3.12.0

This release, 3.12.0rc1, is the penultimate release preview. Entering the release candidate phase, only reviewed code changes which are clear bug fixes are allowed between this release candidate and the final release. The second candidate (and the last planned release preview) is scheduled for Monday, 2023-09-04, while the official release of 3.12.0 is scheduled for Monday, 2023-10-02.

There will be no ABI changes from this point forward in the 3.12 series, and the goal is that there will be as few code changes as possible.

Call to action

We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.12 compatibilities during this phase, and where necessary publish Python 3.12 wheels on PyPI to be ready for the final release of 3.12.0. Any binary wheels built against Python 3.12.0rc1 will work with future versions of Python 3.12. As always, report any issues to the Python bug tracker.

Please keep in mind that this is a preview release and while it’s as close to the final release as we can get it, its use is not recommended for production environments.

Core developers: time to work on documentation now

  • Are all your changes properly documented?
  • Are they mentioned in What’s New?
  • Did you notice other changes you know of to have insufficient documentation?

Major new features of the 3.12 series, compared to 3.11

New features

Type annotations

Deprecations

  • The deprecated wstr and wstr_length members of the C implementation of unicode objects were removed, per PEP 623.
  • In the unittest module, a number of long deprecated methods and classes were removed. (They had been deprecated since Python 3.1 or 3.2).
  • The deprecated smtpd and distutils modules have been removed (see PEP 594 and PEP 632. The setuptools package continues to provide the distutils module.
  • A number of other old, broken and deprecated functions, classes and methods have been removed.
  • Invalid backslash escape sequences in strings now warn with SyntaxWarning instead of DeprecationWarning, making them more visible. (They will become syntax errors in the future.)
  • The internal representation of integers has changed in preparation for performance enhancements. (This should not affect most users as it is an internal detail, but it may cause problems for Cython-generated code.)

(Hey, fellow core developer, if a feature you find important is missing from this list, let Thomas know.)

For more details on the changes to Python 3.12, see What’s new in Python 3.12. The next pre-release of Python 3.12 will be 3.12.0rc2, the final release candidate, currently scheduled for 2023-09-04.

More resources

We hope you enjoy the new releases!

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation.

Your release team,
Thomas Wouters @thomas
Ned Deily @nad
Steve Dower @steve.dower
Łukasz Langa @ambv

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