I'm pleased to announce the release of Python 3.12 beta 1 (and feature
freeze for Python 3.12).

https://www.python.org/downloads/release/python-3120b1/
This is a beta preview of Python 3.12

Python 3.12 is still in development. This release, 3.12.0b1, is the first
of four planned 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 (Issues · python/cpython · GitHub) 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 beta 4 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 recommended 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
<https://peps.python.org/pep-0695/>).
- More flexible f-string parsing, allowing many things previously
disallowed (PEP 701 <https://peps.python.org/pep-0701/>).
- 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
<https://peps.python.org/pep-0709/>).
- Support for the Linux perf profiler to report Python function names in
traces.
- The deprecated wstr and wstr_length members of the C implementation of
unicode objects were removed, per PEP 623
<https://peps.python.org/pep-0623/>.
- 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 <https://peps.python.org/pep-0594/> and PEP 632
<https://peps.python.org/pep-0632/>. The setuptools package (installed
by default in virtualenvs and many other places) 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 <thomas@python.org>.)

For more details on the changes to Python 3.12, see What’s new in Python
3.12 <https://docs.python.org/dev/whatsnew/3.12.html>. The next pre-release
of Python 3.12 will be 3.12.0b2, currently scheduled for 2023-05-29.


More resources

Online Documentation <https://docs.python.org/3.12/>.
PEP 693 <https://www.python.org/dev/peps/pep-0693/>, the Python 3.12
Release Schedule.
Report bugs via GitHub Issues <https://github.com/python/cpython/issues>.
Help fund Python and its community <https://www.python.org/psf/donations/>.


And now for something completely different

As the first beta release marks the point at which we fork off the release branch from the main development branch, here’s a poem about forks in the road.

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves, no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I —
I took the one less traveled by,
And that has made all the difference.


*The Road Not Taken*, by Robert Frost.

Enjoy the new release

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
Ned Deily
Steve Dower
--
Thomas Wouters <thomas@python.org>

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On 25/05/2023 12:23, Robin Becker wrote:

On 22/05/2023 22:04, Thomas Wouters wrote:

I'm pleased to announce the release of Python 3.12 beta 1 (and feature freeze for Python 3.12).

.......
I see a major difference between 3.12.0a7 and 3.12.0b1

Basically in preppy an importer is defined to handle imports of '.prep' files.

This worked as expected in the a7 version and fails in the b1. I put in some prints in the code and I see these calls
for the a7 run> $ ~/LOCAL/3.12.0a7/bin/python3 test_import.py

sys.meta_path.insert(<preppy.installImporter.<locals>.PreppyImporter object at 0x7fa870b84080>) -->

.........

I think this might be caused by the removal of the find_module method of importlib.abc.MetaPathFinder. So I guess I have
to implement a modernised importer. Apologies for noise if that is the case.
--
Robin Becker

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On 22/05/2023 22:04, Thomas Wouters wrote:

I'm pleased to announce the release of Python 3.12 beta 1 (and feature freeze for Python 3.12).

.......
I see a major difference between 3.12.0a7 and 3.12.0b1

Basically in preppy an importer is defined to handle imports of '.prep' files.

This worked as expected in the a7 version and fails in the b1. I put in some prints in the code and I see these calls
for the a7 run> $ ~/LOCAL/3.12.0a7/bin/python3 test_import.py

sys.meta_path.insert(<preppy.installImporter.<locals>.PreppyImporter object at 0x7fa870b84080>) -->

[<preppy.installImporter.<locals>.PreppyImporter object at 0x7fa870b84080>, <_distutils_hack.DistutilsMetaFinder object
at 0x7fa871290fb0>, <class '_frozen_importlib.BuiltinImporter'>, <class '_frozen_importlib.FrozenImporter'>, <class
'_frozen_importlib_external.PathFinder'>]

PreppyImporter.find_module('sample001',None) PreppyImporter.load_module('sample001')
4
.
----------------------------------------------------------------------
Ran 1 test in 0.004s

OK

In 3.12.0b1 although the importer is inserted into sys.meta_path the find_module/load_module methods are never called.
and the import fails.

So is this an expected change in the way importers behave or a bug?

$ ~/LOCAL/3.12.0b1/bin/python3 test_import.py sys.meta_path.insert(<preppy.installImporter.<locals>.PreppyImporter object at 0x7fc866ecb110>) -->

[<preppy.installImporter.<locals>.PreppyImporter object at 0x7fc866ecb110>, <class '_frozen_importlib.BuiltinImporter'>,
<class '_frozen_importlib.FrozenImporter'>, <class '_frozen_importlib_external.PathFinder'>]

E
====================================================================== ERROR: testImport1 (__main__.ImportTestCase.testImport1) ---------------------------------------------------------------------- Traceback (most recent call last):
File "/home/robin/devel/reportlab/REPOS/preppy/tmp/test_import.py", line 13, in testImport1
import sample001
ModuleNotFoundError: No module named 'sample001'

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (errors=1)

..........

Your release team,
Thomas Wouters
Ned Deily
Steve Dower

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