From d60b97a833fd3284f2ee249d32c97fc359d83486 Mon Sep 17 00:00:00 2001 From: Adam Turner <9087854+AA-Turner@users.noreply.github.com> Date: Sat, 17 Aug 2024 13:09:42 +0100 Subject: GH-109975: Copyedit 3.13 What's New: Other Language Changes (#123086) Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> --- Doc/whatsnew/3.13.rst | 258 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 156 insertions(+), 102 deletions(-) diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst index 8d2c4e7..382fa1c 100644 --- a/Doc/whatsnew/3.13.rst +++ b/Doc/whatsnew/3.13.rst @@ -242,6 +242,7 @@ Windows support contributed by Dino Viehland and Anthony Shaw.) .. _`PyPy project`: https://pypy.org/ + .. _whatsnew313-improved-error-messages: Improved error messages @@ -492,138 +493,123 @@ Incremental garbage collection The cycle garbage collector is now incremental. This means that maximum pause times are reduced by an order of magnitude or more for larger heaps. +(Contributed by Mark Shannon in :gh:`108362`.) Other Language Changes ====================== -* Classes have a new :attr:`~class.__static_attributes__` attribute, populated by the compiler, - with a tuple of names of attributes of this class which are assigned - through ``self.X`` from any function in its body. (Contributed by Irit Katriel - in :gh:`115775`.) +* The compiler now strips common common leading whitespace + from every line in a docstring. + This reduces the size of the :term:`bytecode cache <bytecode>` + (such as ``.pyc`` files), with reductions in file size of around 5%, + for example in :mod:`!sqlalchemy.orm.session` from SQLAlchemy 2.0. + This change affects tools that use docstrings, such as :mod:`doctest`. + + .. doctest:: + + >>> def spam(): + ... """ + ... This is a docstring with + ... leading whitespace. + ... + ... It even has multiple paragraphs! + ... """ + ... + >>> spam.__doc__ + '\nThis is a docstring with\n leading whitespace.\n\nIt even has multiple paragraphs!\n' -* The :func:`exec` and :func:`eval` built-ins now accept their ``globals`` - and ``locals`` namespace arguments as keywords. - (Contributed by Raphael Gaschignard in :gh:`105879`) + (Contributed by Inada Naoki in :gh:`81283`.) -* Allow the *count* argument of :meth:`str.replace` to be a keyword. - (Contributed by Hugo van Kemenade in :gh:`106487`.) +* :ref:`Annotation scopes <annotation-scopes>` within class scopes + can now contain lambdas and comprehensions. + Comprehensions that are located within class scopes + are not inlined into their parent scope. -* Compiler now strip indents from docstrings. - This will reduce the size of :term:`bytecode cache <bytecode>` (e.g. ``.pyc`` file). - For example, cache file size for ``sqlalchemy.orm.session`` in SQLAlchemy 2.0 - is reduced by about 5%. - This change will affect tools using docstrings, like :mod:`doctest`. - (Contributed by Inada Naoki in :gh:`81283`.) + .. code-block:: python -* The :func:`compile` built-in can now accept a new flag, - ``ast.PyCF_OPTIMIZED_AST``, which is similar to ``ast.PyCF_ONLY_AST`` - except that the returned ``AST`` is optimized according to the value - of the ``optimize`` argument. - (Contributed by Irit Katriel in :gh:`108113`). + class C[T]: + type Alias = lambda: T -* :mod:`multiprocessing`, :mod:`concurrent.futures`, :mod:`compileall`: - Replace :func:`os.cpu_count` with :func:`os.process_cpu_count` to select the - default number of worker threads and processes. Get the CPU affinity - if supported. - (Contributed by Victor Stinner in :gh:`109649`.) + (Contributed by Jelle Zijlstra in :gh:`109118` and :gh:`118160`.) -* :func:`os.path.realpath` now resolves MS-DOS style file names even if - the file is not accessible. - (Contributed by Moonsik Park in :gh:`82367`.) +* :ref:`Future statements <future>` are no longer triggered by + relative imports of the :mod:`__future__` module, + meaning that statements of the form ``from .__future__ import ...`` + are now simply standard relative imports, with no special features activated. + (Contributed by Jeremiah Gabriel Pascual in :gh:`118216`.) -* Fixed a bug where a :keyword:`global` declaration in an :keyword:`except` block - is rejected when the global is used in the :keyword:`else` block. +* :keyword:`global` declarations are now permitted in :keyword:`except` blocks + when that global is used in the :keyword:`else` block. + Previously this raised an erroneous :exc:`SyntaxError`. (Contributed by Irit Katriel in :gh:`111123`.) -* Many functions now emit a warning if a boolean value is passed as - a file descriptor argument. - This can help catch some errors earlier. - (Contributed by Serhiy Storchaka in :gh:`82626`.) - -* Added a new environment variable :envvar:`PYTHON_FROZEN_MODULES`. It - determines whether or not frozen modules are ignored by the import machinery, - equivalent of the :option:`-X frozen_modules <-X>` command-line option. +* Add :envvar:`PYTHON_FROZEN_MODULES`, a new environment variable that + determines whether frozen modules are ignored by the import machinery, + equivalent to the :option:`-X frozen_modules <-X>` command-line option. (Contributed by Yilei Yang in :gh:`111374`.) -* Add :ref:`support for the perf profiler <perf_profiling>` working without - frame pointers through the new environment variable - :envvar:`PYTHON_PERF_JIT_SUPPORT` and command-line option :option:`-X perf_jit - <-X>` (Contributed by Pablo Galindo in :gh:`118518`.) - -* The new :envvar:`PYTHON_HISTORY` environment variable can be used to change - the location of a ``.python_history`` file. - (Contributed by Levi Sabah, Zackery Spytz and Hugo van Kemenade in - :gh:`73965`.) - -* Add :exc:`PythonFinalizationError` exception. This exception derived from - :exc:`RuntimeError` is raised when an operation is blocked during - the :term:`Python finalization <interpreter shutdown>`. - - The following functions now raise PythonFinalizationError, instead of - :exc:`RuntimeError`: - - * :func:`_thread.start_new_thread`. - * :class:`subprocess.Popen`. - * :func:`os.fork`. - * :func:`os.forkpty`. - - (Contributed by Victor Stinner in :gh:`114570`.) - -* Added :attr:`!name` and :attr:`!mode` attributes for compressed - and archived file-like objects in modules :mod:`bz2`, :mod:`lzma`, - :mod:`tarfile` and :mod:`zipfile`. - (Contributed by Serhiy Storchaka in :gh:`115961`.) - -* Allow controlling Expat >=2.6.0 reparse deferral (:cve:`2023-52425`) - by adding five new methods: +* Add :ref:`support for the perf profiler <perf_profiling>` working + without `frame pointers <https://en.wikipedia.org/wiki/Call_stack>`_ through + the new environment variable :envvar:`PYTHON_PERF_JIT_SUPPORT` + and command-line option :option:`-X perf_jit <-X>`. + (Contributed by Pablo Galindo in :gh:`118518`.) - * :meth:`xml.etree.ElementTree.XMLParser.flush` - * :meth:`xml.etree.ElementTree.XMLPullParser.flush` - * :meth:`xml.parsers.expat.xmlparser.GetReparseDeferralEnabled` - * :meth:`xml.parsers.expat.xmlparser.SetReparseDeferralEnabled` - * :meth:`!xml.sax.expatreader.ExpatParser.flush` +* The location of a :file:`.python_history` file can be changed via the + new :envvar:`PYTHON_HISTORY` environment variable. + (Contributed by Levi Sabah, Zackery Spytz and Hugo van Kemenade + in :gh:`73965`.) - (Contributed by Sebastian Pipping in :gh:`115623`.) +* Classes have a new :attr:`~class.__static_attributes__` attribute. + This is populated by the compiler with a tuple of the class's attribute names + which are assigned through ``self.<name>`` from any function in its body. + (Contributed by Irit Katriel in :gh:`115775`.) -* The :func:`ssl.create_default_context` API now includes - :data:`ssl.VERIFY_X509_PARTIAL_CHAIN` and :data:`ssl.VERIFY_X509_STRICT` - in its default flags. +* The compiler now creates a :attr:`!__firstlineno__` attribute on classes + with the line number of the first line of the class definition. + (Contributed by Serhiy Storchaka in :gh:`118465`.) - .. note:: +* The :func:`exec` and :func:`eval` builtins now accept + the *globals* and *locals* arguments as keywords. + (Contributed by Raphael Gaschignard in :gh:`105879`) - :data:`ssl.VERIFY_X509_STRICT` may reject pre-:rfc:`5280` or malformed - certificates that the underlying OpenSSL implementation otherwise would - accept. While disabling this is not recommended, you can do so using:: +* The :func:`compile` builtin now accepts a new flag, + ``ast.PyCF_OPTIMIZED_AST``, which is similar to ``ast.PyCF_ONLY_AST`` + except that the returned AST is optimized according to + the value of the *optimize* argument. + (Contributed by Irit Katriel in :gh:`108113`). - ctx = ssl.create_default_context() - ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT +* Add :exc:`PythonFinalizationError`, a new exception derived from + :exc:`RuntimeError` and used to signal when operations are blocked + during :term:`finalization <interpreter shutdown>`. + The following callables now raise :exc:`!PythonFinalizationError`, + instead of :exc:`RuntimeError`: - (Contributed by William Woodruff in :gh:`112389`.) + * :func:`_thread.start_new_thread` + * :func:`os.fork` + * :func:`os.forkpty` + * :class:`subprocess.Popen` -* The :class:`configparser.ConfigParser` now accepts unnamed sections before named - ones if configured to do so. - (Contributed by Pedro Sousa Lacerda in :gh:`66449`.) + (Contributed by Victor Stinner in :gh:`114570`.) -* :ref:`annotation scope <annotation-scopes>` within class scopes can now - contain lambdas and comprehensions. Comprehensions that are located within - class scopes are not inlined into their parent scope. (Contributed by - Jelle Zijlstra in :gh:`109118` and :gh:`118160`.) +* Allow the *count* argument of :meth:`str.replace` to be a keyword. + (Contributed by Hugo van Kemenade in :gh:`106487`.) -* Classes have a new :attr:`!__firstlineno__` attribute, - populated by the compiler, with the line number of the first line - of the class definition. - (Contributed by Serhiy Storchaka in :gh:`118465`.) +* Many functions now emit a warning if a boolean value is passed as + a file descriptor argument. + This can help catch some errors earlier. + (Contributed by Serhiy Storchaka in :gh:`82626`.) -* ``from __future__ import ...`` statements are now just normal - relative imports if dots are present before the module name. - (Contributed by Jeremiah Gabriel Pascual in :gh:`118216`.) +* Added :attr:`!name` and :attr:`!mode` attributes + for compressed and archived file-like objects in + the :mod:`bz2`, :mod:`lzma`, :mod:`tarfile`, and :mod:`zipfile` modules. + (Contributed by Serhiy Storchaka in :gh:`115961`.) New Modules =========== -* :mod:`dbm.sqlite3`: SQLite backend for :mod:`dbm`. +* :mod:`dbm.sqlite3`: An SQLite backend for :mod:`dbm`. (Contributed by Raymond Hettinger and Erlend E. Aasland in :gh:`100414`.) @@ -748,6 +734,23 @@ base64 See the `Z85 specification <https://rfc.zeromq.org/spec/32/>`_ for more information. (Contributed by Matan Perelman in :gh:`75299`.) + +compileall +---------- + +* Select the default number of worker threads and processes using + :func:`os.process_cpu_count` instead of :func:`os.cpu_count`. + (Contributed by Victor Stinner in :gh:`109649`.) + + +concurrent.futures +------------------ + +* Select the default number of worker threads and processes using + :func:`os.process_cpu_count` instead of :func:`os.cpu_count`. + (Contributed by Victor Stinner in :gh:`109649`.) + + copy ---- @@ -965,6 +968,15 @@ mmap is inaccessible due to file system errors or access violations. (Contributed by Jannis Weigend in :gh:`118209`.) + +multiprocessing +--------------- + +* Select the default number of worker threads and processes using + :func:`os.process_cpu_count` instead of :func:`os.cpu_count`. + (Contributed by Victor Stinner in :gh:`109649`.) + + opcode ------ @@ -1029,10 +1041,15 @@ os.path * Add :func:`os.path.isreserved` to check if a path is reserved on the current system. This function is only available on Windows. (Contributed by Barney Gale in :gh:`88569`.) + * On Windows, :func:`os.path.isabs` no longer considers paths starting with exactly one (back)slash to be absolute. (Contributed by Barney Gale and Jon Foster in :gh:`44626`.) +* :func:`os.path.realpath` now resolves MS-DOS style file names even if + the file is not accessible. + (Contributed by Moonsik Park in :gh:`82367`.) + * Add support of *dir_fd* and *follow_symlinks* keyword arguments in :func:`shutil.chown`. (Contributed by Berker Peksag and Tahia K in :gh:`62308`) @@ -1132,6 +1149,26 @@ sqlite3 for filtering database objects to dump. (Contributed by Mariusz Felisiak in :gh:`91602`.) + +ssl +--- + +* The :func:`ssl.create_default_context` API now includes + :data:`ssl.VERIFY_X509_PARTIAL_CHAIN` and :data:`ssl.VERIFY_X509_STRICT` + in its default flags. + + .. note:: + + :data:`ssl.VERIFY_X509_STRICT` may reject pre-:rfc:`5280` or malformed + certificates that the underlying OpenSSL implementation otherwise would + accept. While disabling this is not recommended, you can do so using:: + + ctx = ssl.create_default_context() + ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT + + (Contributed by William Woodruff in :gh:`112389`.) + + statistics ---------- @@ -1297,13 +1334,26 @@ warnings warning may also be emitted when a decorated function or class is used at runtime. See :pep:`702`. (Contributed by Jelle Zijlstra in :gh:`104003`.) -xml.etree.ElementTree ---------------------- + +xml +--- + +* Allow controlling Expat >=2.6.0 reparse deferral (:cve:`2023-52425`) + by adding five new methods: + + * :meth:`xml.etree.ElementTree.XMLParser.flush` + * :meth:`xml.etree.ElementTree.XMLPullParser.flush` + * :meth:`xml.parsers.expat.xmlparser.GetReparseDeferralEnabled` + * :meth:`xml.parsers.expat.xmlparser.SetReparseDeferralEnabled` + * :meth:`!xml.sax.expatreader.ExpatParser.flush` + + (Contributed by Sebastian Pipping in :gh:`115623`.) * Add the :meth:`!close` method for the iterator returned by :func:`~xml.etree.ElementTree.iterparse` for explicit cleaning up. (Contributed by Serhiy Storchaka in :gh:`69893`.) + zipimport --------- @@ -1459,6 +1509,10 @@ PEP 594: dead batteries (and other module removals) configparser ------------ +* The :class:`configparser.ConfigParser` now accepts unnamed sections + before named ones if configured to do so. + (Contributed by Pedro Sousa Lacerda in :gh:`66449`.) + * Remove the undocumented :class:`!configparser.LegacyInterpolation` class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. -- cgit v0.12