Mailing List Archive

[RELEASE] Python 3.12.0 beta 4 released
Not much time left! I’ve released 3.12.0 beta 4. We’re now in the run-up to
rc1, so keep that in mind when you backport to the 3.12 branch.

*This is a beta preview of Python 3.12*
Python 3.12 is still in development. This release, 3.12.0b4, is the final
of four beta release previews of 3.12.

Beta release previews are intended to give the wider community the
opportunity to test new features and bug fixes and to prepare their
projects to support the new feature release.

We *strongly encourage* maintainers of third-party Python projects to *test
with 3.12* during the beta phase and report issues found to the Python bug
tracker <> as soon as possible.
While the release is planned to be feature complete entering the beta
phase, it is possible that features may be modified or, in rare cases,
deleted up until the start of the release candidate phase (Monday,
2023-07-31). Our goal is to have no ABI changes after this release, and as
few code changes as possible after 3.12.0rc1, the first release candidate.
To achieve that, it will be *extremely important* to get as much exposure
for 3.12 as possible during the beta phase.

Please keep in mind that this is a preview release and its use is *not
for production environments.

*Major new features of the 3.12 series, compared to 3.11*
Some of the new major new features and changes in Python 3.12 are:

- New type annotation syntax for generic classes (PEP 695
- More flexible f-string parsing, allowing many things previously
disallowed (PEP 701 <>).
- Support for the buffer protocol in Python code (PEP 688
- Even more improved error messages. More exceptions potentially caused
by typos now make suggestions to the user.
- Many large and small performance improvements (like PEP 709
- Support for the Linux perf profiler to report Python function names in
- 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 3.12.0rc1, the *first release candidate*,
currently scheduled for 2023-07-31.

*More resources*
Online Documentation <>.
PEP 693 <>, the Python 3.12
Release Schedule.
Report bugs via GitHub Issues <>.
Help fund Python and its community <>.

*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 <>.

Regards from the alternating thunderstorms and heat waves in Amsterdam,
Thomas Wouters.

Your release team,
Ned Deily
Steve Dower
?ukasz Langa

Thomas Wouters <>