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authorSerhiy Storchaka <storchaka@gmail.com>2019-10-14 16:10:40 +0300
committerŁukasz Langa <lukasz@langa.pl>2019-10-14 15:10:40 +0200
commit298439ce3fb01de6c3110cc4847e6afe3253ba7a (patch)
treed6cab8e824b9850f59b8ed50149ccdfb90a950c0
parent19d6842c15c145f65178f806048ac1a8ae7d05f6 (diff)
downloadcpython-git-298439ce3fb01de6c3110cc4847e6afe3253ba7a.tar.gz
bpo-37759: Polish What's New in Python 3.8. (#16769)
-rw-r--r--Doc/whatsnew/3.8.rst211
1 files changed, 123 insertions, 88 deletions
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index 0c59ef8015..8108fb7e14 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -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