[RELEASE] Python 3.7.0b2 is now available for testing

Ned Deily nad at python.org
Wed Feb 28 01:04:32 EST 2018

On behalf of the Python development community and the Python 3.7 release
team, I'm happy to announce the availability of Python 3.7.0b2.  b2 is
the second of four planned beta releases of Python 3.7, the next major
release of Python, and marks the end of the feature development phase
for 3.7.  You can find Python 3.7.0b2 here:


Among the new major new features in Python 3.7 are:

* PEP 538, Coercing the legacy C locale to a UTF-8 based locale
* PEP 539, A New C-API for Thread-Local Storage in CPython
* PEP 540, UTF-8 mode
* PEP 552, Deterministic pyc
* PEP 553, Built-in breakpoint()
* PEP 557, Data Classes
* PEP 560, Core support for typing module and generic types
* PEP 562, Module __getattr__ and __dir__
* PEP 563, Postponed Evaluation of Annotations
* PEP 564, Time functions with nanosecond resolution
* PEP 565, Show DeprecationWarning in __main__
* PEP 567, Context Variables

Please see "What’s New In Python 3.7" for more information.
Additional documentation for these features and for other changes
will be provided during the beta phase.


Beta releases are intended to give you the opportunity to test new
features and bug fixes and to prepare their projects to support the
new feature release. We strongly encourage you to test your projects
with 3.7 during the beta phase and report issues found to
https://bugs.python.org as soon as possible.

While the release is 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 (2018-05-21). Our goal
is have no ABI changes after beta 3 and no code changes after rc1.
To achieve that, it will be extremely important to get as much exposure
for 3.7 as possible during the beta phase.

Attention macOS users: as of b1, there is a new installer variant for
macOS 10.9+ that includes a built-in version of Tcl/Tk 8.6. This
variant is expected to become the default version when 3.7.0 releases.
Check it out! We welcome your feedback.

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

The next planned release of Python 3.7 will be 3.7.0b3, currently
scheduled for 2018-03-26. More information about the release schedule
can be found here:


  Ned Deily
  nad at python.org -- []

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