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Commit 298439ce authored by Serhiy Storchaka's avatar Serhiy Storchaka Committed by Łukasz Langa
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bpo-37759: Polish What's New in Python 3.8. (#16769)

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Doc/whatsnew/3.8.rst
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......@@ -212,6 +212,7 @@ subdirectories).
(Contributed by Carl Meyer in :issue:`33499`.)
Debug build uses the same ABI as release build
-----------------------------------------------
......@@ -285,6 +286,7 @@ calculations can be shown::
(Contributed by Eric V. Smith and Larry Hastings in :issue:`36817`.)
PEP 587: Python Initialization Configuration
--------------------------------------------
......@@ -411,7 +413,8 @@ Other Language Changes
* The syntax allowed for keyword names in function calls was further
restricted. In particular, ``f((keyword)=arg)`` is no longer allowed. It was
never intended to permit more than a bare name on the left-hand side of a
keyword argument assignment term. See :issue:`34641`.
keyword argument assignment term.
(Contributed by Benjamin Peterson in :issue:`34641`.)
* Generalized iterable unpacking in :keyword:`yield` and
:keyword:`return` statements no longer requires enclosing parentheses.
......@@ -425,7 +428,6 @@ Other Language Changes
>>> parse('simpsons homer marge bart lisa sally')
('SIMPSONS', 'homer', 'marge', 'bart', 'lisa', 'sally')
(Contributed by David Cuthbert and Jordan Chapman in :issue:`32117`.)
* When a comma is missed in code such as ``[(10, 20) (30, 40)]``, the
......@@ -521,6 +523,8 @@ Other Language Changes
'łukasz langa': 'Łukasz Langa',
'walter dörwald': 'Walter Dörwald'}
(Contributed by Jörn Heissler in :issue:`35224`.)
New Modules
===========
......@@ -544,13 +548,12 @@ New Modules
PackagePath('requests-2.22.0.dist-info/RECORD'),
PackagePath('requests-2.22.0.dist-info/WHEEL')]
(Contributed in :issue:`34632` by Barry Warsaw and Jason R. Coombs.)
(Contributed by Barry Warsaw and Jason R. Coombs in :issue:`34632`.)
Improved Modules
================
ast
---
......@@ -558,6 +561,11 @@ AST nodes now have ``end_lineno`` and ``end_col_offset`` attributes,
which give the precise location of the end of the node. (This only
applies to nodes that have ``lineno`` and ``col_offset`` attributes.)
New function :func:`ast.get_source_segment` returns the source code
for a specific AST node.
(Contributed by Ivan Levkivskyi in :issue:`33416`.)
The :func:`ast.parse` function has some new flags:
* ``type_comments=True`` causes it to return the text of :pep:`484` and
......@@ -570,8 +578,7 @@ The :func:`ast.parse` function has some new flags:
version. (For example, ``feature_version=(3, 4)`` will treat
``async`` and ``await`` as non-reserved words.)
New function :func:`ast.get_source_segment` returns the source code
for a specific AST node.
(Contributed by Guido van Rossum in :issue:`35766`.)
asyncio
......@@ -596,7 +603,6 @@ The :func:`compile` built-in has been improved to accept the
:func:`compile` will allow top-level ``await``, ``async for`` and ``async with``
constructs that are usually considered invalid syntax. Asynchronous code object
marked with the ``CO_COROUTINE`` flag may then be returned.
(Contributed by Matthias Bussonnier in :issue:`34616`)
......@@ -627,6 +633,7 @@ to specify flags for the underlying ``LoadLibraryEx`` call. The default flags ar
set to only load DLL dependencies from trusted locations, including the path
where the DLL is stored (if a full or partial path is used to load the initial
DLL) and paths added by :func:`~os.add_dll_directory`.
(Contributed by Steve Dower in :issue:`36085`.)
datetime
......@@ -660,8 +667,8 @@ gc
--
:func:`~gc.get_objects` can now receive an optional *generation* parameter
indicating a generation to get objects from. Contributed in
:issue:`36016` by Pablo Galindo.
indicating a generation to get objects from.
(Contributed by Pablo Galindo in :issue:`36016`.)
gettext
......@@ -723,6 +730,8 @@ for :func:`property`, :func:`classmethod`, and :func:`staticmethod`::
self.bit_rate = round(bit_rate / 1000.0, 1)
self.duration = ceil(duration)
(Contributed by Raymond Hettinger in :issue:`36326`.)
io
--
......@@ -780,7 +789,7 @@ multiprocessing
---------------
Added new :mod:`multiprocessing.shared_memory` module.
(Contributed Davin Potts in :issue:`35813`.)
(Contributed by Davin Potts in :issue:`35813`.)
On macOS, the *spawn* start method is now used by default.
(Contributed by Victor Stinner in :issue:`33725`.)
......@@ -792,6 +801,7 @@ os
Added new function :func:`~os.add_dll_directory` on Windows for providing
additional search paths for native dependencies when importing extension
modules or loading DLLs using :mod:`ctypes`.
(Contributed by Steve Dower in :issue:`36085`.)
A new :func:`os.memfd_create` function was added to wrap the
``memfd_create()`` syscall.
......@@ -812,6 +822,8 @@ and so code that checks ``islink`` first will continue to treat junctions as
directories, while code that handles errors from :func:`os.readlink` may now
treat junctions as links.
(Contributed by Steve Dower in :issue:`37834`.)
os.path
-------
......@@ -827,6 +839,7 @@ characters or bytes unrepresentable at the OS level.
:func:`~os.path.expanduser` on Windows now prefers the :envvar:`USERPROFILE`
environment variable and does not use :envvar:`HOME`, which is not normally set
for regular user accounts.
(Contributed by Anthony Sottile in :issue:`36264`.)
:func:`~os.path.isdir` on Windows no longer returns true for a link to a
non-existent directory.
......@@ -834,6 +847,8 @@ non-existent directory.
:func:`~os.path.realpath` on Windows now resolves reparse points, including
symlinks and directory junctions.
(Contributed by Steve Dower in :issue:`37834`.)
pathlib
-------
......@@ -883,11 +898,12 @@ py_compile
shlex
----------
-----
The new :func:`shlex.join` function acts as the inverse of :func:`shlex.split`.
(Contributed by Bo Bayles in :issue:`32102`.)
shutil
------
......@@ -901,6 +917,7 @@ inherited from the corresponding change to the :mod:`tarfile` module.
:func:`shutil.rmtree` on Windows now removes directory junctions without
recursively removing their contents first.
(Contributed by Steve Dower in :issue:`37834`.)
socket
......@@ -995,18 +1012,18 @@ in a standardized and extensible format, and offers several other benefits.
threading
---------
* Add a new :func:`threading.excepthook` function which handles uncaught
:meth:`threading.Thread.run` exception. It can be overridden to control how
uncaught :meth:`threading.Thread.run` exceptions are handled.
(Contributed by Victor Stinner in :issue:`1230540`.)
Add a new :func:`threading.excepthook` function which handles uncaught
:meth:`threading.Thread.run` exception. It can be overridden to control how
uncaught :meth:`threading.Thread.run` exceptions are handled.
(Contributed by Victor Stinner in :issue:`1230540`.)
* Add a new
:func:`threading.get_native_id` function and a :data:`~threading.Thread.native_id`
attribute to the :class:`threading.Thread` class. These return the native
integral Thread ID of the current thread assigned by the kernel.
This feature is only available on certain platforms, see
:func:`get_native_id <threading.get_native_id>` for more information.
(Contributed by Jake Tesler in :issue:`36084`.)
Add a new :func:`threading.get_native_id` function and
a :data:`~threading.Thread.native_id`
attribute to the :class:`threading.Thread` class. These return the native
integral Thread ID of the current thread assigned by the kernel.
This feature is only available on certain platforms, see
:func:`get_native_id <threading.get_native_id>` for more information.
(Contributed by Jake Tesler in :issue:`36084`.)
tokenize
......@@ -1017,6 +1034,7 @@ provided with input that does not have a trailing new line. This behavior
now matches what the C tokenizer does internally.
(Contributed by Ammar Askar in :issue:`33899`.)
tkinter
-------
......@@ -1036,6 +1054,7 @@ The :class:`tkinter.PhotoImage` class now has
:meth:`~tkinter.PhotoImage.transparency_set` methods. (Contributed by
Zackery Spytz in :issue:`25451`.)
time
----
......@@ -1084,95 +1103,98 @@ The :mod:`typing` module incorporates several new features:
unicodedata
-----------
* The :mod:`unicodedata` module has been upgraded to use the `Unicode 12.1.0
<http://blog.unicode.org/2019/05/unicode-12-1-en.html>`_ release.
The :mod:`unicodedata` module has been upgraded to use the `Unicode 12.1.0
<http://blog.unicode.org/2019/05/unicode-12-1-en.html>`_ release.
* New function :func:`~unicodedata.is_normalized` can be used to verify a string
is in a specific normal form, often much faster than by actually normalizing
the string. (Contributed by Max Belanger, David Euresti, and Greg Price in
:issue:`32285` and :issue:`37966`).
New function :func:`~unicodedata.is_normalized` can be used to verify a string
is in a specific normal form, often much faster than by actually normalizing
the string. (Contributed by Max Belanger, David Euresti, and Greg Price in
:issue:`32285` and :issue:`37966`).
unittest
--------
* Added :class:`AsyncMock` to support an asynchronous version of :class:`Mock`.
Appropriate new assert functions for testing have been added as well.
(Contributed by Lisa Roach in :issue:`26467`).
Added :class:`AsyncMock` to support an asynchronous version of :class:`Mock`.
Appropriate new assert functions for testing have been added as well.
(Contributed by Lisa Roach in :issue:`26467`).
* Added :func:`~unittest.addModuleCleanup()` and
:meth:`~unittest.TestCase.addClassCleanup()` to unittest to support
cleanups for :func:`~unittest.setUpModule()` and
:meth:`~unittest.TestCase.setUpClass()`.
(Contributed by Lisa Roach in :issue:`24412`.)
Added :func:`~unittest.addModuleCleanup()` and
:meth:`~unittest.TestCase.addClassCleanup()` to unittest to support
cleanups for :func:`~unittest.setUpModule()` and
:meth:`~unittest.TestCase.setUpClass()`.
(Contributed by Lisa Roach in :issue:`24412`.)
* Several mock assert functions now also print a list of actual calls upon
failure. (Contributed by Petter Strandmark in :issue:`35047`.)
Several mock assert functions now also print a list of actual calls upon
failure. (Contributed by Petter Strandmark in :issue:`35047`.)
* :mod:`unittest` module gained support for coroutines to be used as test cases
with :class:`unittest.IsolatedAsyncioTestCase`.
(Contributed by Andrew Svetlov in :issue:`32972`.)
:mod:`unittest` module gained support for coroutines to be used as test cases
with :class:`unittest.IsolatedAsyncioTestCase`.
(Contributed by Andrew Svetlov in :issue:`32972`.)
Example::
Example::
import unittest
import unittest
class TestRequest(unittest.IsolatedAsyncioTestCase):
class TestRequest(unittest.IsolatedAsyncioTestCase):
async def asyncSetUp(self):
self.connection = await AsyncConnection()
async def asyncSetUp(self):
self.connection = await AsyncConnection()
async def test_get(self):
response = await self.connection.get("https://example.com")
self.assertEqual(response.status_code, 200)
async def test_get(self):
response = await self.connection.get("https://example.com")
self.assertEqual(response.status_code, 200)
async def asyncTearDown(self):
await self.connection.close()
async def asyncTearDown(self):
await self.connection.close()
if __name__ == "__main__":
unittest.main()
if __name__ == "__main__":
unittest.main()
venv
----
* :mod:`venv` now includes an ``Activate.ps1`` script on all platforms for
activating virtual environments under PowerShell Core 6.1.
(Contributed by Brett Cannon in :issue:`32718`.)
:mod:`venv` now includes an ``Activate.ps1`` script on all platforms for
activating virtual environments under PowerShell Core 6.1.
(Contributed by Brett Cannon in :issue:`32718`.)
weakref
-------
* The proxy objects returned by :func:`weakref.proxy` now support the matrix
multiplication operators ``@`` and ``@=`` in addition to the other
numeric operators. (Contributed by Mark Dickinson in :issue:`36669`.)
The proxy objects returned by :func:`weakref.proxy` now support the matrix
multiplication operators ``@`` and ``@=`` in addition to the other
numeric operators. (Contributed by Mark Dickinson in :issue:`36669`.)
xml
---
* As mitigation against DTD and external entity retrieval, the
:mod:`xml.dom.minidom` and :mod:`xml.sax` modules no longer process
external entities by default.
(Contributed by Christian Heimes in :issue:`17239`.)
As mitigation against DTD and external entity retrieval, the
:mod:`xml.dom.minidom` and :mod:`xml.sax` modules no longer process
external entities by default.
(Contributed by Christian Heimes in :issue:`17239`.)
* The ``.find*()`` methods in the :mod:`xml.etree.ElementTree` module
support wildcard searches like ``{*}tag`` which ignores the namespace
and ``{namespace}*`` which returns all tags in the given namespace.
(Contributed by Stefan Behnel in :issue:`28238`.)
The ``.find*()`` methods in the :mod:`xml.etree.ElementTree` module
support wildcard searches like ``{*}tag`` which ignores the namespace
and ``{namespace}*`` which returns all tags in the given namespace.
(Contributed by Stefan Behnel in :issue:`28238`.)
* The :mod:`xml.etree.ElementTree` module provides a new function
:func:`–xml.etree.ElementTree.canonicalize()` that implements C14N 2.0.
(Contributed by Stefan Behnel in :issue:`13611`.)
The :mod:`xml.etree.ElementTree` module provides a new function
:func:`–xml.etree.ElementTree.canonicalize()` that implements C14N 2.0.
(Contributed by Stefan Behnel in :issue:`13611`.)
The target object of :class:`xml.etree.ElementTree.XMLParser` can
receive namespace declaration events through the new callback methods
``start_ns()`` and ``end_ns()``. Additionally, the
:class:`xml.etree.ElementTree.TreeBuilder` target can be configured
to process events about comments and processing instructions to include
them in the generated tree.
(Contributed by Stefan Behnel in :issue:`36676` and :issue:`36673`.)
* The target object of :class:`xml.etree.ElementTree.XMLParser` can
receive namespace declaration events through the new callback methods
``start_ns()`` and ``end_ns()``. Additionally, the
:class:`xml.etree.ElementTree.TreeBuilder` target can be configured
to process events about comments and processing instructions to include
them in the generated tree.
(Contributed by Stefan Behnel in :issue:`36676` and :issue:`36673`.)
Optimizations
=============
......@@ -1220,6 +1242,7 @@ Optimizations
(Contributed by Inada Naoki in :issue:`33597`)
* :class:`uuid.UUID` now uses ``__slots__`` to reduce its memory footprint.
(Contributed by Wouter Bolsterlee and Tal Einat in :issue:`30977`)
* Improved performance of :func:`operator.itemgetter` by 33%. Optimized
argument handling and added a fast path for the common case of a single
......@@ -1412,7 +1435,8 @@ Deprecated
for the ``l*gettext()`` functions.
(Contributed by Serhiy Storchaka in :issue:`33710`.)
* The :meth:`~threading.Thread.isAlive()` method of :class:`threading.Thread` has been deprecated.
* The :meth:`~threading.Thread.isAlive()` method of :class:`threading.Thread`
has been deprecated.
(Contributed by Dong-hee Na in :issue:`35283`.)
* Many builtin and extension functions that take integer arguments will
......@@ -1516,7 +1540,7 @@ Changes in Python behavior
* The compiler now produces a :exc:`SyntaxWarning` when identity checks
(``is`` and ``is not``) are used with certain types of literals
(e.g. strings, ints). These can often work by accident in CPython,
(e.g. strings, numbers). These can often work by accident in CPython,
but are not guaranteed by the language spec. The warning advises users
to use equality tests (``==`` and ``!=``) instead.
(Contributed by Serhiy Storchaka in :issue:`34850`.)
......@@ -1545,6 +1569,8 @@ Changes in Python behavior
:c:func:`Py_END_ALLOW_THREADS`, and :c:func:`PyGILState_Ensure`. If this
behavior is not desired, guard the call by checking :c:func:`_Py_IsFinalizing`
or :c:func:`sys.is_finalizing`.
(Contributed by Joannah Nanjekye in :issue:`36475`.)
Changes in the Python API
-------------------------
......@@ -1569,6 +1595,7 @@ Changes in the Python API
* The :meth:`imap.IMAP4.logout` method no longer ignores silently arbitrary
exceptions.
(Contributed by Victor Stinner in :issue:`36348`.)
* The function :func:`platform.popen` has been removed, after having been deprecated since
Python 3.3: use :func:`os.popen` instead.
......@@ -1657,8 +1684,9 @@ Changes in the Python API
* :func:`~os.path.expanduser` on Windows now prefers the :envvar:`USERPROFILE`
environment variable and does not use :envvar:`HOME`, which is not normally
set for regular user accounts.
(Contributed by Anthony Sottile in :issue:`36264`.)
* The Exception :class:`asyncio.CancelledError` now inherits from
* The exception :class:`asyncio.CancelledError` now inherits from
:class:`BaseException` rather than a :class:`Exception`.
(Contributed by Yury Selivanov in :issue:`13528`.)
......@@ -1675,7 +1703,7 @@ Changes in the Python API
directory while loading your library. Note that Windows 7 users will need to
ensure that Windows Update KB2533625 has been installed (this is also verified
by the installer).
(See :issue:`36085`.)
(Contributed by Steve Dower in :issue:`36085`.)
* The header files and functions related to pgen have been removed after its
replacement by a pure Python implementation. (Contributed by Pablo Galindo
......@@ -1696,6 +1724,7 @@ Changes in the C API
field. It should be initialized to ``PY_MINOR_VERSION``. The field is ignored
by default, and is used if and only if ``PyCF_ONLY_AST`` flag is set in
*cf_flags*.
(Contributed by Guido van Rossum in :issue:`35766`.)
* The :c:func:`PyEval_ReInitThreads` function has been removed from the C API.
It should not be called explicitly: use :c:func:`PyOS_AfterFork_Child`
......@@ -1742,7 +1771,9 @@ Changes in the C API
:c:func:`PyObject_GC_NewVar`, or any other custom allocator that uses
:c:func:`PyObject_Init` or :c:func:`PyObject_INIT`.
Example::
Example:
.. code-block:: c
static foo_struct *
foo_new(PyObject *type) {
......@@ -1759,7 +1790,9 @@ Changes in the C API
* Ensure that all custom ``tp_dealloc`` functions of heap-allocated types
decrease the type's reference count.
Example::
Example:
.. code-block:: c
static void
foo_dealloc(foo_struct *instance) {
......@@ -1776,7 +1809,9 @@ Changes in the C API
* The :c:macro:`Py_DEPRECATED()` macro has been implemented for MSVC.
The macro now must be placed before the symbol name.
Example::
Example:
.. code-block:: c
Py_DEPRECATED(3.8) PyAPI_FUNC(int) Py_OldFunction(void);
......@@ -1797,12 +1832,12 @@ Changes in the C API
* The functions :c:func:`PyNode_AddChild` and :c:func:`PyParser_AddToken` now accept
two additional ``int`` arguments *end_lineno* and *end_col_offset*.
.. highlight:: shell
* The :file:`libpython38.a` file to allow MinGW tools to link directly against
:file:`python38.dll` is no longer included in the regular Windows distribution.
If you require this file, it may be generated with the ``gendef`` and
``dlltool`` tools, which are part of the MinGW binutils package::
``dlltool`` tools, which are part of the MinGW binutils package:
.. code-block:: shell
gendef python38.dll > tmp.def
dlltool --dllname python38.dll --def tmp.def --output-lib libpython38.a
......@@ -1813,7 +1848,7 @@ Changes in the C API
placed in the same directory as :file:`pythonXY.lib`, which is generally the
:file:`libs` directory under your Python installation.
.. highlight:: python3
(Contributed by Steve Dower in :issue:`37351`.)
CPython bytecode changes
......
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