1577 lines
65 KiB
ReStructuredText
1577 lines
65 KiB
ReStructuredText
****************************
|
|
What's New In Python 3.9
|
|
****************************
|
|
|
|
:Release: |release|
|
|
:Date: |today|
|
|
:Editor: Łukasz Langa
|
|
|
|
.. Rules for maintenance:
|
|
|
|
* Anyone can add text to this document. Your text might get
|
|
rewritten to some degree.
|
|
|
|
* The maintainer will go through Misc/NEWS periodically and add
|
|
changes; it's therefore more important to add your changes to
|
|
Misc/NEWS than to this file.
|
|
|
|
* This is not a complete list of every single change; completeness
|
|
is the purpose of Misc/NEWS. Some changes will be too small
|
|
or esoteric to include. If such a change is added to the text,
|
|
it might get removed during final editing.
|
|
|
|
* If you want to draw your new text to the attention of the
|
|
maintainer, add 'XXX' to the beginning of the paragraph or
|
|
section.
|
|
|
|
* It's OK to just add a fragmentary note about a change. For
|
|
example: "XXX Describe the transmogrify() function added to the
|
|
socket module." The maintainer will research the change and
|
|
write the necessary text.
|
|
|
|
* You can comment out your additions if you like, but it's not
|
|
necessary (especially when a final release is some months away).
|
|
|
|
* Credit the author of a patch or bugfix. Just the name is
|
|
sufficient; the e-mail address isn't necessary.
|
|
|
|
* It's helpful to add the bug/patch number as a comment:
|
|
|
|
XXX Describe the transmogrify() function added to the socket
|
|
module.
|
|
(Contributed by P.Y. Developer in :issue:`12345`.)
|
|
|
|
This saves the maintainer the effort of going through the Mercurial log
|
|
when researching a change.
|
|
|
|
This article explains the new features in Python 3.9, compared to 3.8.
|
|
Python 3.9 was released on October 5th, 2020.
|
|
|
|
For full details, see the :ref:`changelog <changelog>`.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`596` - Python 3.9 Release Schedule
|
|
|
|
|
|
Summary -- Release highlights
|
|
=============================
|
|
|
|
.. This section singles out the most important changes in Python 3.9.
|
|
Brevity is key.
|
|
|
|
New syntax features:
|
|
|
|
* :pep:`584`, union operators added to ``dict``;
|
|
* :pep:`585`, type hinting generics in standard collections;
|
|
* :pep:`614`, relaxed grammar restrictions on decorators.
|
|
|
|
New built-in features:
|
|
|
|
* :pep:`616`, string methods to remove prefixes and suffixes.
|
|
|
|
New features in the standard library:
|
|
|
|
* :pep:`593`, flexible function and variable annotations;
|
|
* :func:`os.pidfd_open` added that allows process management without races
|
|
and signals.
|
|
|
|
Interpreter improvements:
|
|
|
|
* :pep:`573`, fast access to module state from methods of C extension
|
|
types;
|
|
* :pep:`617`, CPython now uses a new parser based on PEG;
|
|
* a number of Python builtins (range, tuple, set, frozenset, list, dict) are
|
|
now sped up using :pep:`590` vectorcall;
|
|
* garbage collection does not block on resurrected objects;
|
|
* a number of Python modules (:mod:`_abc`, :mod:`audioop`, :mod:`_bz2`,
|
|
:mod:`_codecs`, :mod:`_contextvars`, :mod:`_crypt`, :mod:`_functools`,
|
|
:mod:`_json`, :mod:`_locale`, :mod:`math`, :mod:`operator`, :mod:`resource`,
|
|
:mod:`time`, :mod:`_weakref`) now use multiphase initialization as defined
|
|
by PEP 489;
|
|
* a number of standard library modules (:mod:`audioop`, :mod:`ast`, :mod:`grp`,
|
|
:mod:`_hashlib`, :mod:`pwd`, :mod:`_posixsubprocess`, :mod:`random`,
|
|
:mod:`select`, :mod:`struct`, :mod:`termios`, :mod:`zlib`) are now using
|
|
the stable ABI defined by PEP 384.
|
|
|
|
New library modules:
|
|
|
|
* :pep:`615`, the IANA Time Zone Database is now present in the standard
|
|
library in the :mod:`zoneinfo` module;
|
|
* an implementation of a topological sort of a graph is now provided in
|
|
the new :mod:`graphlib` module.
|
|
|
|
Release process changes:
|
|
|
|
* :pep:`602`, CPython adopts an annual release cycle.
|
|
|
|
|
|
You should check for DeprecationWarning in your code
|
|
====================================================
|
|
|
|
When Python 2.7 was still supported, a lot of functionality in Python 3
|
|
was kept for backward compatibility with Python 2.7. With the end of Python
|
|
2 support, these backward compatibility layers have been removed, or will
|
|
be removed soon. Most of them emitted a :exc:`DeprecationWarning` warning for
|
|
several years. For example, using ``collections.Mapping`` instead of
|
|
``collections.abc.Mapping`` emits a :exc:`DeprecationWarning` since Python
|
|
3.3, released in 2012.
|
|
|
|
Test your application with the :option:`-W` ``default`` command-line option to see
|
|
:exc:`DeprecationWarning` and :exc:`PendingDeprecationWarning`, or even with
|
|
:option:`-W` ``error`` to treat them as errors. :ref:`Warnings Filter
|
|
<warning-filter>` can be used to ignore warnings from third-party code.
|
|
|
|
Python 3.9 is the last version providing those Python 2 backward compatibility
|
|
layers, to give more time to Python projects maintainers to organize the
|
|
removal of the Python 2 support and add support for Python 3.9.
|
|
|
|
Aliases to :ref:`Abstract Base Classes <collections-abstract-base-classes>` in
|
|
the :mod:`collections` module, like ``collections.Mapping`` alias to
|
|
:class:`collections.abc.Mapping`, are kept for one last release for backward
|
|
compatibility. They will be removed from Python 3.10.
|
|
|
|
More generally, try to run your tests in the :ref:`Python Development Mode
|
|
<devmode>` which helps to prepare your code to make it compatible with the
|
|
next Python version.
|
|
|
|
Note: a number of pre-existing deprecations were removed in this version of
|
|
Python as well. Consult the :ref:`removed-in-python-39` section.
|
|
|
|
|
|
New Features
|
|
============
|
|
|
|
Dictionary Merge & Update Operators
|
|
-----------------------------------
|
|
|
|
Merge (``|``) and update (``|=``) operators have been added to the built-in
|
|
:class:`dict` class. Those complement the existing ``dict.update`` and
|
|
``{**d1, **d2}`` methods of merging dictionaries.
|
|
|
|
Example::
|
|
|
|
>>> x = {"key1": "value1 from x", "key2": "value2 from x"}
|
|
>>> y = {"key2": "value2 from y", "key3": "value3 from y"}
|
|
>>> x | y
|
|
{'key1': 'value1 from x', 'key2': 'value2 from y', 'key3': 'value3 from y'}
|
|
>>> y | x
|
|
{'key2': 'value2 from x', 'key3': 'value3 from y', 'key1': 'value1 from x'}
|
|
|
|
See :pep:`584` for a full description.
|
|
(Contributed by Brandt Bucher in :issue:`36144`.)
|
|
|
|
New String Methods to Remove Prefixes and Suffixes
|
|
--------------------------------------------------
|
|
|
|
:meth:`str.removeprefix(prefix)<str.removeprefix>` and
|
|
:meth:`str.removesuffix(suffix)<str.removesuffix>` have been added
|
|
to easily remove an unneeded prefix or a suffix from a string. Corresponding
|
|
``bytes``, ``bytearray``, and ``collections.UserString`` methods have also been
|
|
added. See :pep:`616` for a full description. (Contributed by Dennis Sweeney in
|
|
:issue:`39939`.)
|
|
|
|
Type Hinting Generics in Standard Collections
|
|
---------------------------------------------
|
|
|
|
In type annotations you can now use built-in collection types such as
|
|
``list`` and ``dict`` as generic types instead of importing the
|
|
corresponding capitalized types (e.g. ``List`` or ``Dict``) from
|
|
``typing``. Some other types in the standard library are also now generic,
|
|
for example ``queue.Queue``.
|
|
|
|
Example:
|
|
|
|
.. code-block:: python
|
|
|
|
def greet_all(names: list[str]) -> None:
|
|
for name in names:
|
|
print("Hello", name)
|
|
|
|
See :pep:`585` for more details. (Contributed by Guido van Rossum,
|
|
Ethan Smith, and Batuhan Taşkaya in :issue:`39481`.)
|
|
|
|
New Parser
|
|
----------
|
|
|
|
Python 3.9 uses a new parser, based on `PEG
|
|
<https://en.wikipedia.org/wiki/Parsing_expression_grammar>`_ instead
|
|
of `LL(1) <https://en.wikipedia.org/wiki/LL_parser>`_. The new
|
|
parser's performance is roughly comparable to that of the old parser,
|
|
but the PEG formalism is more flexible than LL(1) when it comes to
|
|
designing new language features. We'll start using this flexibility
|
|
in Python 3.10 and later.
|
|
|
|
The :mod:`ast` module uses the new parser and produces the same AST as
|
|
the old parser.
|
|
|
|
In Python 3.10, the old parser will be deleted and so will all
|
|
functionality that depends on it (primarily the :mod:`parser` module,
|
|
which has long been deprecated). In Python 3.9 *only*, you can switch
|
|
back to the LL(1) parser using a command line switch (``-X
|
|
oldparser``) or an environment variable (``PYTHONOLDPARSER=1``).
|
|
|
|
See :pep:`617` for more details. (Contributed by Guido van Rossum,
|
|
Pablo Galindo and Lysandros Nikolaou in :issue:`40334`.)
|
|
|
|
|
|
Other Language Changes
|
|
======================
|
|
|
|
* :func:`__import__` now raises :exc:`ImportError` instead of
|
|
:exc:`ValueError`, which used to occur when a relative import went past
|
|
its top-level package.
|
|
(Contributed by Ngalim Siregar in :issue:`37444`.)
|
|
|
|
* Python now gets the absolute path of the script filename specified on
|
|
the command line (ex: ``python3 script.py``): the ``__file__`` attribute of
|
|
the :mod:`__main__` module became an absolute path, rather than a relative
|
|
path. These paths now remain valid after the current directory is changed
|
|
by :func:`os.chdir`. As a side effect, the traceback also displays the
|
|
absolute path for :mod:`__main__` module frames in this case.
|
|
(Contributed by Victor Stinner in :issue:`20443`.)
|
|
|
|
* In the :ref:`Python Development Mode <devmode>` and in debug build, the
|
|
*encoding* and *errors* arguments are now checked for string encoding and
|
|
decoding operations. Examples: :func:`open`, :meth:`str.encode` and
|
|
:meth:`bytes.decode`.
|
|
|
|
By default, for best performance, the *errors* argument is only checked at
|
|
the first encoding/decoding error and the *encoding* argument is sometimes
|
|
ignored for empty strings.
|
|
(Contributed by Victor Stinner in :issue:`37388`.)
|
|
|
|
* ``"".replace("", s, n)`` now returns ``s`` instead of an empty string for
|
|
all non-zero ``n``. It is now consistent with ``"".replace("", s)``.
|
|
There are similar changes for :class:`bytes` and :class:`bytearray` objects.
|
|
(Contributed by Serhiy Storchaka in :issue:`28029`.)
|
|
|
|
* Any valid expression can now be used as a :term:`decorator`. Previously, the
|
|
grammar was much more restrictive. See :pep:`614` for details.
|
|
(Contributed by Brandt Bucher in :issue:`39702`.)
|
|
|
|
* Improved help for the :mod:`typing` module. Docstrings are now shown for
|
|
all special forms and special generic aliases (like ``Union`` and ``List``).
|
|
Using :func:`help` with generic alias like ``List[int]`` will show the help
|
|
for the correspondent concrete type (``list`` in this case).
|
|
(Contributed by Serhiy Storchaka in :issue:`40257`.)
|
|
|
|
* Parallel running of :meth:`~agen.aclose` / :meth:`~agen.asend` /
|
|
:meth:`~agen.athrow` is now prohibited, and ``ag_running`` now reflects
|
|
the actual running status of the async generator.
|
|
(Contributed by Yury Selivanov in :issue:`30773`.)
|
|
|
|
* Unexpected errors in calling the ``__iter__`` method are no longer masked by
|
|
``TypeError`` in the :keyword:`in` operator and functions
|
|
:func:`~operator.contains`, :func:`~operator.indexOf` and
|
|
:func:`~operator.countOf` of the :mod:`operator` module.
|
|
(Contributed by Serhiy Storchaka in :issue:`40824`.)
|
|
|
|
* Unparenthesized lambda expressions can no longer be the expression part in an
|
|
``if`` clause in comprehensions and generator expressions. See :issue:`41848`
|
|
and :issue:`43755` for details.
|
|
|
|
|
|
New Modules
|
|
===========
|
|
|
|
zoneinfo
|
|
--------
|
|
|
|
The :mod:`zoneinfo` module brings support for the IANA time zone database to
|
|
the standard library. It adds :class:`zoneinfo.ZoneInfo`, a concrete
|
|
:class:`datetime.tzinfo` implementation backed by the system's time zone data.
|
|
|
|
Example::
|
|
|
|
>>> from zoneinfo import ZoneInfo
|
|
>>> from datetime import datetime, timedelta
|
|
|
|
>>> # Daylight saving time
|
|
>>> dt = datetime(2020, 10, 31, 12, tzinfo=ZoneInfo("America/Los_Angeles"))
|
|
>>> print(dt)
|
|
2020-10-31 12:00:00-07:00
|
|
>>> dt.tzname()
|
|
'PDT'
|
|
|
|
>>> # Standard time
|
|
>>> dt += timedelta(days=7)
|
|
>>> print(dt)
|
|
2020-11-07 12:00:00-08:00
|
|
>>> print(dt.tzname())
|
|
PST
|
|
|
|
|
|
As a fall-back source of data for platforms that don't ship the IANA database,
|
|
the |tzdata|_ module was released as a first-party package -- distributed via
|
|
PyPI and maintained by the CPython core team.
|
|
|
|
.. |tzdata| replace:: ``tzdata``
|
|
.. _tzdata: https://pypi.org/project/tzdata/
|
|
|
|
.. seealso::
|
|
|
|
:pep:`615` -- Support for the IANA Time Zone Database in the Standard Library
|
|
PEP written and implemented by Paul Ganssle
|
|
|
|
|
|
graphlib
|
|
---------
|
|
|
|
A new module, :mod:`graphlib`, was added that contains the
|
|
:class:`graphlib.TopologicalSorter` class to offer functionality to perform
|
|
topological sorting of graphs. (Contributed by Pablo Galindo, Tim Peters and
|
|
Larry Hastings in :issue:`17005`.)
|
|
|
|
|
|
Improved Modules
|
|
================
|
|
|
|
ast
|
|
---
|
|
|
|
Added the *indent* option to :func:`~ast.dump` which allows it to produce a
|
|
multiline indented output.
|
|
(Contributed by Serhiy Storchaka in :issue:`37995`.)
|
|
|
|
Added :func:`ast.unparse` as a function in the :mod:`ast` module that can
|
|
be used to unparse an :class:`ast.AST` object and produce a string with code
|
|
that would produce an equivalent :class:`ast.AST` object when parsed.
|
|
(Contributed by Pablo Galindo and Batuhan Taskaya in :issue:`38870`.)
|
|
|
|
Added docstrings to AST nodes that contains the ASDL signature used to
|
|
construct that node. (Contributed by Batuhan Taskaya in :issue:`39638`.)
|
|
|
|
asyncio
|
|
-------
|
|
|
|
Due to significant security concerns, the *reuse_address* parameter of
|
|
:meth:`asyncio.loop.create_datagram_endpoint` is no longer supported. This is
|
|
because of the behavior of the socket option ``SO_REUSEADDR`` in UDP. For more
|
|
details, see the documentation for ``loop.create_datagram_endpoint()``.
|
|
(Contributed by Kyle Stanley, Antoine Pitrou, and Yury Selivanov in
|
|
:issue:`37228`.)
|
|
|
|
Added a new :term:`coroutine` :meth:`~asyncio.loop.shutdown_default_executor`
|
|
that schedules a shutdown for the default executor that waits on the
|
|
:class:`~concurrent.futures.ThreadPoolExecutor` to finish closing. Also,
|
|
:func:`asyncio.run` has been updated to use the new :term:`coroutine`.
|
|
(Contributed by Kyle Stanley in :issue:`34037`.)
|
|
|
|
Added :class:`asyncio.PidfdChildWatcher`, a Linux-specific child watcher
|
|
implementation that polls process file descriptors. (:issue:`38692`)
|
|
|
|
Added a new :term:`coroutine` :func:`asyncio.to_thread`. It is mainly used for
|
|
running IO-bound functions in a separate thread to avoid blocking the event
|
|
loop, and essentially works as a high-level version of
|
|
:meth:`~asyncio.loop.run_in_executor` that can directly take keyword arguments.
|
|
(Contributed by Kyle Stanley and Yury Selivanov in :issue:`32309`.)
|
|
|
|
When cancelling the task due to a timeout, :meth:`asyncio.wait_for` will now
|
|
wait until the cancellation is complete also in the case when *timeout* is
|
|
<= 0, like it does with positive timeouts.
|
|
(Contributed by Elvis Pranskevichus in :issue:`32751`.)
|
|
|
|
:mod:`asyncio` now raises :exc:`TyperError` when calling incompatible
|
|
methods with an :class:`ssl.SSLSocket` socket.
|
|
(Contributed by Ido Michael in :issue:`37404`.)
|
|
|
|
compileall
|
|
----------
|
|
|
|
Added new possibility to use hardlinks for duplicated ``.pyc`` files: *hardlink_dupes* parameter and --hardlink-dupes command line option.
|
|
(Contributed by Lumír 'Frenzy' Balhar in :issue:`40495`.)
|
|
|
|
Added new options for path manipulation in resulting ``.pyc`` files: *stripdir*, *prependdir*, *limit_sl_dest* parameters and -s, -p, -e command line options.
|
|
Added the possibility to specify the option for an optimization level multiple times.
|
|
(Contributed by Lumír 'Frenzy' Balhar in :issue:`38112`.)
|
|
|
|
concurrent.futures
|
|
------------------
|
|
|
|
Added a new *cancel_futures* parameter to
|
|
:meth:`concurrent.futures.Executor.shutdown` that cancels all pending futures
|
|
which have not started running, instead of waiting for them to complete before
|
|
shutting down the executor.
|
|
(Contributed by Kyle Stanley in :issue:`39349`.)
|
|
|
|
Removed daemon threads from :class:`~concurrent.futures.ThreadPoolExecutor`
|
|
and :class:`~concurrent.futures.ProcessPoolExecutor`. This improves
|
|
compatibility with subinterpreters and predictability in their shutdown
|
|
processes. (Contributed by Kyle Stanley in :issue:`39812`.)
|
|
|
|
Workers in :class:`~concurrent.futures.ProcessPoolExecutor` are now spawned on
|
|
demand, only when there are no available idle workers to reuse. This optimizes
|
|
startup overhead and reduces the amount of lost CPU time to idle workers.
|
|
(Contributed by Kyle Stanley in :issue:`39207`.)
|
|
|
|
curses
|
|
------
|
|
|
|
Added :func:`curses.get_escdelay`, :func:`curses.set_escdelay`,
|
|
:func:`curses.get_tabsize`, and :func:`curses.set_tabsize` functions.
|
|
(Contributed by Anthony Sottile in :issue:`38312`.)
|
|
|
|
datetime
|
|
--------
|
|
The :meth:`~datetime.date.isocalendar()` of :class:`datetime.date`
|
|
and :meth:`~datetime.datetime.isocalendar()` of :class:`datetime.datetime`
|
|
methods now returns a :func:`~collections.namedtuple` instead of a :class:`tuple`.
|
|
(Contributed by Dong-hee Na in :issue:`24416`.)
|
|
|
|
distutils
|
|
---------
|
|
|
|
The :command:`upload` command now creates SHA2-256 and Blake2b-256 hash
|
|
digests. It skips MD5 on platforms that block MD5 digest.
|
|
(Contributed by Christian Heimes in :issue:`40698`.)
|
|
|
|
fcntl
|
|
-----
|
|
|
|
Added constants :data:`~fcntl.F_OFD_GETLK`, :data:`~fcntl.F_OFD_SETLK`
|
|
and :data:`~fcntl.F_OFD_SETLKW`.
|
|
(Contributed by Dong-hee Na in :issue:`38602`.)
|
|
|
|
ftplib
|
|
-------
|
|
|
|
:class:`~ftplib.FTP` and :class:`~ftplib.FTP_TLS` now raise a :class:`ValueError`
|
|
if the given timeout for their constructor is zero to prevent the creation of
|
|
a non-blocking socket. (Contributed by Dong-hee Na in :issue:`39259`.)
|
|
|
|
gc
|
|
--
|
|
|
|
When the garbage collector makes a collection in which some objects resurrect
|
|
(they are reachable from outside the isolated cycles after the finalizers have
|
|
been executed), do not block the collection of all objects that are still
|
|
unreachable. (Contributed by Pablo Galindo and Tim Peters in :issue:`38379`.)
|
|
|
|
Added a new function :func:`gc.is_finalized` to check if an object has been
|
|
finalized by the garbage collector. (Contributed by Pablo Galindo in
|
|
:issue:`39322`.)
|
|
|
|
hashlib
|
|
-------
|
|
|
|
The :mod:`hashlib` module can now use SHA3 hashes and SHAKE XOF from OpenSSL
|
|
when available.
|
|
(Contributed by Christian Heimes in :issue:`37630`.)
|
|
|
|
Builtin hash modules can now be disabled with
|
|
``./configure --without-builtin-hashlib-hashes`` or selectively enabled with
|
|
e.g. ``./configure --with-builtin-hashlib-hashes=sha3,blake2`` to force use
|
|
of OpenSSL based implementation.
|
|
(Contributed by Christian Heimes in :issue:`40479`)
|
|
|
|
|
|
http
|
|
----
|
|
|
|
HTTP status codes ``103 EARLY_HINTS``, ``418 IM_A_TEAPOT`` and ``425 TOO_EARLY`` are added to
|
|
:class:`http.HTTPStatus`. (Contributed by Dong-hee Na in :issue:`39509` and Ross Rhodes in :issue:`39507`.)
|
|
|
|
IDLE and idlelib
|
|
----------------
|
|
|
|
Added option to toggle cursor blink off. (Contributed by Zackery Spytz
|
|
in :issue:`4603`.)
|
|
|
|
Escape key now closes IDLE completion windows. (Contributed by Johnny
|
|
Najera in :issue:`38944`.)
|
|
|
|
Added keywords to module name completion list. (Contributed by Terry J.
|
|
Reedy in :issue:`37765`.)
|
|
|
|
The changes above have been backported to 3.8 maintenance releases.
|
|
|
|
imaplib
|
|
-------
|
|
|
|
:class:`~imaplib.IMAP4` and :class:`~imaplib.IMAP4_SSL` now have
|
|
an optional *timeout* parameter for their constructors.
|
|
Also, the :meth:`~imaplib.IMAP4.open` method now has an optional *timeout* parameter
|
|
with this change. The overridden methods of :class:`~imaplib.IMAP4_SSL` and
|
|
:class:`~imaplib.IMAP4_stream` were applied to this change.
|
|
(Contributed by Dong-hee Na in :issue:`38615`.)
|
|
|
|
:meth:`imaplib.IMAP4.unselect` is added.
|
|
:meth:`imaplib.IMAP4.unselect` frees server's resources associated with the
|
|
selected mailbox and returns the server to the authenticated
|
|
state. This command performs the same actions as :meth:`imaplib.IMAP4.close`, except
|
|
that no messages are permanently removed from the currently
|
|
selected mailbox. (Contributed by Dong-hee Na in :issue:`40375`.)
|
|
|
|
importlib
|
|
---------
|
|
|
|
To improve consistency with import statements, :func:`importlib.util.resolve_name`
|
|
now raises :exc:`ImportError` instead of :exc:`ValueError` for invalid relative
|
|
import attempts.
|
|
(Contributed by Ngalim Siregar in :issue:`37444`.)
|
|
|
|
Import loaders which publish immutable module objects can now publish
|
|
immutable packages in addition to individual modules.
|
|
(Contributed by Dino Viehland in :issue:`39336`.)
|
|
|
|
Added :func:`importlib.resources.files` function with support for
|
|
subdirectories in package data, matching backport in ``importlib_resources``
|
|
version 1.5.
|
|
(Contributed by Jason R. Coombs in :issue:`39791`.)
|
|
|
|
Refreshed ``importlib.metadata`` from ``importlib_metadata`` version 1.6.1.
|
|
|
|
inspect
|
|
-------
|
|
|
|
:attr:`inspect.BoundArguments.arguments` is changed from ``OrderedDict`` to regular
|
|
dict. (Contributed by Inada Naoki in :issue:`36350` and :issue:`39775`.)
|
|
|
|
ipaddress
|
|
---------
|
|
|
|
:mod:`ipaddress` now supports IPv6 Scoped Addresses (IPv6 address with suffix ``%<scope_id>``).
|
|
|
|
Scoped IPv6 addresses can be parsed using :class:`ipaddress.IPv6Address`.
|
|
If present, scope zone ID is available through the :attr:`~ipaddress.IPv6Address.scope_id` attribute.
|
|
(Contributed by Oleksandr Pavliuk in :issue:`34788`.)
|
|
|
|
Starting with Python 3.9.5 the :mod:`ipaddress` module no longer
|
|
accepts any leading zeros in IPv4 address strings.
|
|
(Contributed by Christian Heimes in :issue:`36384`).
|
|
|
|
math
|
|
----
|
|
|
|
Expanded the :func:`math.gcd` function to handle multiple arguments.
|
|
Formerly, it only supported two arguments.
|
|
(Contributed by Serhiy Storchaka in :issue:`39648`.)
|
|
|
|
Added :func:`math.lcm`: return the least common multiple of specified arguments.
|
|
(Contributed by Mark Dickinson, Ananthakrishnan and Serhiy Storchaka in
|
|
:issue:`39479` and :issue:`39648`.)
|
|
|
|
Added :func:`math.nextafter`: return the next floating-point value after *x*
|
|
towards *y*.
|
|
(Contributed by Victor Stinner in :issue:`39288`.)
|
|
|
|
Added :func:`math.ulp`: return the value of the least significant bit
|
|
of a float.
|
|
(Contributed by Victor Stinner in :issue:`39310`.)
|
|
|
|
multiprocessing
|
|
---------------
|
|
|
|
The :class:`multiprocessing.SimpleQueue` class has a new
|
|
:meth:`~multiprocessing.SimpleQueue.close` method to explicitly close the
|
|
queue.
|
|
(Contributed by Victor Stinner in :issue:`30966`.)
|
|
|
|
nntplib
|
|
-------
|
|
|
|
:class:`~nntplib.NNTP` and :class:`~nntplib.NNTP_SSL` now raise a :class:`ValueError`
|
|
if the given timeout for their constructor is zero to prevent the creation of
|
|
a non-blocking socket. (Contributed by Dong-hee Na in :issue:`39259`.)
|
|
|
|
os
|
|
--
|
|
|
|
Added :data:`~os.CLD_KILLED` and :data:`~os.CLD_STOPPED` for :attr:`si_code`.
|
|
(Contributed by Dong-hee Na in :issue:`38493`.)
|
|
|
|
Exposed the Linux-specific :func:`os.pidfd_open` (:issue:`38692`) and
|
|
:data:`os.P_PIDFD` (:issue:`38713`) for process management with file
|
|
descriptors.
|
|
|
|
The :func:`os.unsetenv` function is now also available on Windows.
|
|
(Contributed by Victor Stinner in :issue:`39413`.)
|
|
|
|
The :func:`os.putenv` and :func:`os.unsetenv` functions are now always
|
|
available.
|
|
(Contributed by Victor Stinner in :issue:`39395`.)
|
|
|
|
Added :func:`os.waitstatus_to_exitcode` function:
|
|
convert a wait status to an exit code.
|
|
(Contributed by Victor Stinner in :issue:`40094`.)
|
|
|
|
pathlib
|
|
-------
|
|
|
|
Added :meth:`pathlib.Path.readlink()` which acts similarly to
|
|
:func:`os.readlink`.
|
|
(Contributed by Girts Folkmanis in :issue:`30618`)
|
|
|
|
pdb
|
|
---
|
|
|
|
On Windows now :class:`~pdb.Pdb` supports ``~/.pdbrc``.
|
|
(Contributed by Tim Hopper and Dan Lidral-Porter in :issue:`20523`.)
|
|
|
|
poplib
|
|
------
|
|
|
|
:class:`~poplib.POP3` and :class:`~poplib.POP3_SSL` now raise a :class:`ValueError`
|
|
if the given timeout for their constructor is zero to prevent the creation of
|
|
a non-blocking socket. (Contributed by Dong-hee Na in :issue:`39259`.)
|
|
|
|
pprint
|
|
------
|
|
|
|
:mod:`pprint` can now pretty-print :class:`types.SimpleNamespace`.
|
|
(Contributed by Carl Bordum Hansen in :issue:`37376`.)
|
|
|
|
pydoc
|
|
-----
|
|
|
|
The documentation string is now shown not only for class, function,
|
|
method etc, but for any object that has its own ``__doc__`` attribute.
|
|
(Contributed by Serhiy Storchaka in :issue:`40257`.)
|
|
|
|
random
|
|
------
|
|
|
|
Added a new :attr:`random.Random.randbytes` method: generate random bytes.
|
|
(Contributed by Victor Stinner in :issue:`40286`.)
|
|
|
|
signal
|
|
------
|
|
|
|
Exposed the Linux-specific :func:`signal.pidfd_send_signal` for sending to
|
|
signals to a process using a file descriptor instead of a pid. (:issue:`38712`)
|
|
|
|
smtplib
|
|
-------
|
|
|
|
:class:`~smtplib.SMTP` and :class:`~smtplib.SMTP_SSL` now raise a :class:`ValueError`
|
|
if the given timeout for their constructor is zero to prevent the creation of
|
|
a non-blocking socket. (Contributed by Dong-hee Na in :issue:`39259`.)
|
|
|
|
:class:`~smtplib.LMTP` constructor now has an optional *timeout* parameter.
|
|
(Contributed by Dong-hee Na in :issue:`39329`.)
|
|
|
|
socket
|
|
------
|
|
|
|
The :mod:`socket` module now exports the :data:`~socket.CAN_RAW_JOIN_FILTERS`
|
|
constant on Linux 4.1 and greater.
|
|
(Contributed by Stefan Tatschner and Zackery Spytz in :issue:`25780`.)
|
|
|
|
The socket module now supports the :data:`~socket.CAN_J1939` protocol on
|
|
platforms that support it. (Contributed by Karl Ding in :issue:`40291`.)
|
|
|
|
The socket module now has the :func:`socket.send_fds` and
|
|
:func:`socket.recv_fds` functions. (Contributed by Joannah Nanjekye, Shinya
|
|
Okano and Victor Stinner in :issue:`28724`.)
|
|
|
|
|
|
time
|
|
----
|
|
|
|
On AIX, :func:`~time.thread_time` is now implemented with ``thread_cputime()``
|
|
which has nanosecond resolution, rather than
|
|
``clock_gettime(CLOCK_THREAD_CPUTIME_ID)`` which has a resolution of 10 ms.
|
|
(Contributed by Batuhan Taskaya in :issue:`40192`)
|
|
|
|
sys
|
|
---
|
|
|
|
Added a new :attr:`sys.platlibdir` attribute: name of the platform-specific
|
|
library directory. It is used to build the path of standard library and the
|
|
paths of installed extension modules. It is equal to ``"lib"`` on most
|
|
platforms. On Fedora and SuSE, it is equal to ``"lib64"`` on 64-bit platforms.
|
|
(Contributed by Jan Matějek, Matěj Cepl, Charalampos Stratakis and Victor Stinner in :issue:`1294959`.)
|
|
|
|
Previously, :attr:`sys.stderr` was block-buffered when non-interactive. Now
|
|
``stderr`` defaults to always being line-buffered.
|
|
(Contributed by Jendrik Seipp in :issue:`13601`.)
|
|
|
|
tracemalloc
|
|
-----------
|
|
|
|
Added :func:`tracemalloc.reset_peak` to set the peak size of traced memory
|
|
blocks to the current size, to measure the peak of specific pieces of code.
|
|
(Contributed by Huon Wilson in :issue:`40630`.)
|
|
|
|
typing
|
|
------
|
|
|
|
:pep:`593` introduced an :data:`typing.Annotated` type to decorate existing
|
|
types with context-specific metadata and new ``include_extras`` parameter to
|
|
:func:`typing.get_type_hints` to access the metadata at runtime. (Contributed
|
|
by Till Varoquaux and Konstantin Kashin.)
|
|
|
|
unicodedata
|
|
-----------
|
|
|
|
The Unicode database has been updated to version 13.0.0. (:issue:`39926`).
|
|
|
|
venv
|
|
----
|
|
|
|
The activation scripts provided by :mod:`venv` now all specify their prompt
|
|
customization consistently by always using the value specified by
|
|
``__VENV_PROMPT__``. Previously some scripts unconditionally used
|
|
``__VENV_PROMPT__``, others only if it happened to be set (which was the default
|
|
case), and one used ``__VENV_NAME__`` instead.
|
|
(Contributed by Brett Cannon in :issue:`37663`.)
|
|
|
|
xml
|
|
---
|
|
|
|
White space characters within attributes are now preserved when serializing
|
|
:mod:`xml.etree.ElementTree` to XML file. EOLNs are no longer normalized
|
|
to "\n". This is the result of discussion about how to interpret
|
|
section 2.11 of XML spec.
|
|
(Contributed by Mefistotelis in :issue:`39011`.)
|
|
|
|
|
|
Optimizations
|
|
=============
|
|
|
|
* Optimized the idiom for assignment a temporary variable in comprehensions.
|
|
Now ``for y in [expr]`` in comprehensions is as fast as a simple assignment
|
|
``y = expr``. For example:
|
|
|
|
sums = [s for s in [0] for x in data for s in [s + x]]
|
|
|
|
Unlike the ``:=`` operator this idiom does not leak a variable to the
|
|
outer scope.
|
|
|
|
(Contributed by Serhiy Storchaka in :issue:`32856`.)
|
|
|
|
* Optimized signal handling in multithreaded applications. If a thread different
|
|
than the main thread gets a signal, the bytecode evaluation loop is no longer
|
|
interrupted at each bytecode instruction to check for pending signals which
|
|
cannot be handled. Only the main thread of the main interpreter can handle
|
|
signals.
|
|
|
|
Previously, the bytecode evaluation loop was interrupted at each instruction
|
|
until the main thread handles signals.
|
|
(Contributed by Victor Stinner in :issue:`40010`.)
|
|
|
|
* Optimized the :mod:`subprocess` module on FreeBSD using ``closefrom()``.
|
|
(Contributed by Ed Maste, Conrad Meyer, Kyle Evans, Kubilay Kocak and Victor
|
|
Stinner in :issue:`38061`.)
|
|
|
|
* :c:func:`PyLong_FromDouble` is now up to 1.87x faster for values that
|
|
fit into :c:type:`long`.
|
|
(Contributed by Sergey Fedoseev in :issue:`37986`.)
|
|
|
|
* A number of Python builtins (:class:`range`, :class:`tuple`, :class:`set`,
|
|
:class:`frozenset`, :class:`list`, :class:`dict`) are now sped up by using
|
|
:pep:`590` vectorcall protocol.
|
|
(Contributed by Dong-hee Na, Mark Shannon, Jeroen Demeyer and Petr Viktorin in :issue:`37207`.)
|
|
|
|
* Optimized :func:`~set.difference_update` for the case when the other set
|
|
is much larger than the base set.
|
|
(Suggested by Evgeny Kapun with code contributed by Michele Orrù in :issue:`8425`.)
|
|
|
|
* Python's small object allocator (``obmalloc.c``) now allows (no more than)
|
|
one empty arena to remain available for immediate reuse, without returning
|
|
it to the OS. This prevents thrashing in simple loops where an arena could
|
|
be created and destroyed anew on each iteration.
|
|
(Contributed by Tim Peters in :issue:`37257`.)
|
|
|
|
* :term:`floor division` of float operation now has a better performance. Also
|
|
the message of :exc:`ZeroDivisionError` for this operation is updated.
|
|
(Contributed by Dong-hee Na in :issue:`39434`.)
|
|
|
|
* Decoding short ASCII strings with UTF-8 and ascii codecs is now about
|
|
15% faster. (Contributed by Inada Naoki in :issue:`37348`.)
|
|
|
|
Here's a summary of performance improvements from Python 3.4 through Python 3.9:
|
|
|
|
.. code-block:: none
|
|
|
|
Python version 3.4 3.5 3.6 3.7 3.8 3.9
|
|
-------------- --- --- --- --- --- ---
|
|
|
|
Variable and attribute read access:
|
|
read_local 7.1 7.1 5.4 5.1 3.9 3.9
|
|
read_nonlocal 7.1 8.1 5.8 5.4 4.4 4.5
|
|
read_global 15.5 19.0 14.3 13.6 7.6 7.8
|
|
read_builtin 21.1 21.6 18.5 19.0 7.5 7.8
|
|
read_classvar_from_class 25.6 26.5 20.7 19.5 18.4 17.9
|
|
read_classvar_from_instance 22.8 23.5 18.8 17.1 16.4 16.9
|
|
read_instancevar 32.4 33.1 28.0 26.3 25.4 25.3
|
|
read_instancevar_slots 27.8 31.3 20.8 20.8 20.2 20.5
|
|
read_namedtuple 73.8 57.5 45.0 46.8 18.4 18.7
|
|
read_boundmethod 37.6 37.9 29.6 26.9 27.7 41.1
|
|
|
|
Variable and attribute write access:
|
|
write_local 8.7 9.3 5.5 5.3 4.3 4.3
|
|
write_nonlocal 10.5 11.1 5.6 5.5 4.7 4.8
|
|
write_global 19.7 21.2 18.0 18.0 15.8 16.7
|
|
write_classvar 92.9 96.0 104.6 102.1 39.2 39.8
|
|
write_instancevar 44.6 45.8 40.0 38.9 35.5 37.4
|
|
write_instancevar_slots 35.6 36.1 27.3 26.6 25.7 25.8
|
|
|
|
Data structure read access:
|
|
read_list 24.2 24.5 20.8 20.8 19.0 19.5
|
|
read_deque 24.7 25.5 20.2 20.6 19.8 20.2
|
|
read_dict 24.3 25.7 22.3 23.0 21.0 22.4
|
|
read_strdict 22.6 24.3 19.5 21.2 18.9 21.5
|
|
|
|
Data structure write access:
|
|
write_list 27.1 28.5 22.5 21.6 20.0 20.0
|
|
write_deque 28.7 30.1 22.7 21.8 23.5 21.7
|
|
write_dict 31.4 33.3 29.3 29.2 24.7 25.4
|
|
write_strdict 28.4 29.9 27.5 25.2 23.1 24.5
|
|
|
|
Stack (or queue) operations:
|
|
list_append_pop 93.4 112.7 75.4 74.2 50.8 50.6
|
|
deque_append_pop 43.5 57.0 49.4 49.2 42.5 44.2
|
|
deque_append_popleft 43.7 57.3 49.7 49.7 42.8 46.4
|
|
|
|
Timing loop:
|
|
loop_overhead 0.5 0.6 0.4 0.3 0.3 0.3
|
|
|
|
These results were generated from the variable access benchmark script at:
|
|
``Tools/scripts/var_access_benchmark.py``. The benchmark script displays timings
|
|
in nanoseconds. The benchmarks were measured on an
|
|
`Intel® Core™ i7-4960HQ processor
|
|
<https://ark.intel.com/content/www/us/en/ark/products/76088/intel-core-i7-4960hq-processor-6m-cache-up-to-3-80-ghz.html>`_
|
|
running the macOS 64-bit builds found at
|
|
`python.org <https://www.python.org/downloads/mac-osx/>`_.
|
|
|
|
|
|
Deprecated
|
|
==========
|
|
|
|
* The distutils ``bdist_msi`` command is now deprecated, use
|
|
``bdist_wheel`` (wheel packages) instead.
|
|
(Contributed by Hugo van Kemenade in :issue:`39586`.)
|
|
|
|
* Currently :func:`math.factorial` accepts :class:`float` instances with
|
|
non-negative integer values (like ``5.0``). It raises a :exc:`ValueError`
|
|
for non-integral and negative floats. It is now deprecated. In future
|
|
Python versions it will raise a :exc:`TypeError` for all floats.
|
|
(Contributed by Serhiy Storchaka in :issue:`37315`.)
|
|
|
|
* The :mod:`parser` and :mod:`symbol` modules are deprecated and will be
|
|
removed in future versions of Python. For the majority of use cases,
|
|
users can leverage the Abstract Syntax Tree (AST) generation and compilation
|
|
stage, using the :mod:`ast` module.
|
|
|
|
* The Public C API functions :c:func:`PyParser_SimpleParseStringFlags`,
|
|
:c:func:`PyParser_SimpleParseStringFlagsFilename`,
|
|
:c:func:`PyParser_SimpleParseFileFlags` and :c:func:`PyNode_Compile`
|
|
are deprecated and will be removed in Python 3.10 together with the old parser.
|
|
|
|
* Using :data:`NotImplemented` in a boolean context has been deprecated,
|
|
as it is almost exclusively the result of incorrect rich comparator
|
|
implementations. It will be made a :exc:`TypeError` in a future version
|
|
of Python.
|
|
(Contributed by Josh Rosenberg in :issue:`35712`.)
|
|
|
|
* The :mod:`random` module currently accepts any hashable type as a
|
|
possible seed value. Unfortunately, some of those types are not
|
|
guaranteed to have a deterministic hash value. After Python 3.9,
|
|
the module will restrict its seeds to :const:`None`, :class:`int`,
|
|
:class:`float`, :class:`str`, :class:`bytes`, and :class:`bytearray`.
|
|
|
|
* Opening the :class:`~gzip.GzipFile` file for writing without specifying
|
|
the *mode* argument is deprecated. In future Python versions it will always
|
|
be opened for reading by default. Specify the *mode* argument for opening
|
|
it for writing and silencing a warning.
|
|
(Contributed by Serhiy Storchaka in :issue:`28286`.)
|
|
|
|
* Deprecated the ``split()`` method of :class:`_tkinter.TkappType` in
|
|
favour of the ``splitlist()`` method which has more consistent and
|
|
predicable behavior.
|
|
(Contributed by Serhiy Storchaka in :issue:`38371`.)
|
|
|
|
* The explicit passing of coroutine objects to :func:`asyncio.wait` has been
|
|
deprecated and will be removed in version 3.11.
|
|
(Contributed by Yury Selivanov and Kyle Stanley in :issue:`34790`.)
|
|
|
|
* binhex4 and hexbin4 standards are now deprecated. The :mod:`binhex` module
|
|
and the following :mod:`binascii` functions are now deprecated:
|
|
|
|
* :func:`~binascii.b2a_hqx`, :func:`~binascii.a2b_hqx`
|
|
* :func:`~binascii.rlecode_hqx`, :func:`~binascii.rledecode_hqx`
|
|
|
|
(Contributed by Victor Stinner in :issue:`39353`.)
|
|
|
|
* :mod:`ast` classes ``slice``, ``Index`` and ``ExtSlice`` are considered deprecated
|
|
and will be removed in future Python versions. ``value`` itself should be
|
|
used instead of ``Index(value)``. ``Tuple(slices, Load())`` should be
|
|
used instead of ``ExtSlice(slices)``.
|
|
(Contributed by Serhiy Storchaka in :issue:`34822`.)
|
|
|
|
* :mod:`ast` classes ``Suite``, ``Param``, ``AugLoad`` and ``AugStore``
|
|
are considered deprecated and will be removed in future Python versions.
|
|
They were not generated by the parser and not accepted by the code
|
|
generator in Python 3.
|
|
(Contributed by Batuhan Taskaya in :issue:`39639` and :issue:`39969`
|
|
and Serhiy Storchaka in :issue:`39988`.)
|
|
|
|
* The :c:func:`PyEval_InitThreads` and :c:func:`PyEval_ThreadsInitialized`
|
|
functions are now deprecated and will be removed in Python 3.11. Calling
|
|
:c:func:`PyEval_InitThreads` now does nothing. The :term:`GIL` is initialized
|
|
by :c:func:`Py_Initialize()` since Python 3.7.
|
|
(Contributed by Victor Stinner in :issue:`39877`.)
|
|
|
|
* Passing ``None`` as the first argument to the :func:`shlex.split` function
|
|
has been deprecated. (Contributed by Zackery Spytz in :issue:`33262`.)
|
|
|
|
* :func:`smtpd.MailmanProxy` is now deprecated as it is unusable without
|
|
an external module, ``mailman``. (Contributed by Samuel Colvin in :issue:`35800`.)
|
|
|
|
* The :mod:`lib2to3` module now emits a :exc:`PendingDeprecationWarning`.
|
|
Python 3.9 switched to a PEG parser (see :pep:`617`), and Python 3.10 may
|
|
include new language syntax that is not parsable by lib2to3's LL(1) parser.
|
|
The ``lib2to3`` module may be removed from the standard library in a future
|
|
Python version. Consider third-party alternatives such as `LibCST`_ or
|
|
`parso`_.
|
|
(Contributed by Carl Meyer in :issue:`40360`.)
|
|
|
|
* The *random* parameter of :func:`random.shuffle` has been deprecated.
|
|
(Contributed by Raymond Hettinger in :issue:`40465`)
|
|
|
|
.. _LibCST: https://libcst.readthedocs.io/
|
|
.. _parso: https://parso.readthedocs.io/
|
|
|
|
.. _removed-in-python-39:
|
|
|
|
Removed
|
|
=======
|
|
|
|
* The erroneous version at :data:`unittest.mock.__version__` has been removed.
|
|
|
|
* :class:`nntplib.NNTP`: ``xpath()`` and ``xgtitle()`` methods have been removed.
|
|
These methods are deprecated since Python 3.3. Generally, these extensions
|
|
are not supported or not enabled by NNTP server administrators.
|
|
For ``xgtitle()``, please use :meth:`nntplib.NNTP.descriptions` or
|
|
:meth:`nntplib.NNTP.description` instead.
|
|
(Contributed by Dong-hee Na in :issue:`39366`.)
|
|
|
|
* :class:`array.array`: ``tostring()`` and ``fromstring()`` methods have been
|
|
removed. They were aliases to ``tobytes()`` and ``frombytes()``, deprecated
|
|
since Python 3.2.
|
|
(Contributed by Victor Stinner in :issue:`38916`.)
|
|
|
|
* The undocumented ``sys.callstats()`` function has been removed. Since Python
|
|
3.7, it was deprecated and always returned :const:`None`. It required a special
|
|
build option ``CALL_PROFILE`` which was already removed in Python 3.7.
|
|
(Contributed by Victor Stinner in :issue:`37414`.)
|
|
|
|
* The ``sys.getcheckinterval()`` and ``sys.setcheckinterval()`` functions have
|
|
been removed. They were deprecated since Python 3.2. Use
|
|
:func:`sys.getswitchinterval` and :func:`sys.setswitchinterval` instead.
|
|
(Contributed by Victor Stinner in :issue:`37392`.)
|
|
|
|
* The C function ``PyImport_Cleanup()`` has been removed. It was documented as:
|
|
"Empty the module table. For internal use only."
|
|
(Contributed by Victor Stinner in :issue:`36710`.)
|
|
|
|
* ``_dummy_thread`` and ``dummy_threading`` modules have been removed. These
|
|
modules were deprecated since Python 3.7 which requires threading support.
|
|
(Contributed by Victor Stinner in :issue:`37312`.)
|
|
|
|
* ``aifc.openfp()`` alias to ``aifc.open()``, ``sunau.openfp()`` alias to
|
|
``sunau.open()``, and ``wave.openfp()`` alias to :func:`wave.open()` have been
|
|
removed. They were deprecated since Python 3.7.
|
|
(Contributed by Victor Stinner in :issue:`37320`.)
|
|
|
|
* The :meth:`~threading.Thread.isAlive()` method of :class:`threading.Thread`
|
|
has been removed. It was deprecated since Python 3.8.
|
|
Use :meth:`~threading.Thread.is_alive()` instead.
|
|
(Contributed by Dong-hee Na in :issue:`37804`.)
|
|
|
|
* Methods ``getchildren()`` and ``getiterator()`` of classes
|
|
:class:`~xml.etree.ElementTree.ElementTree` and
|
|
:class:`~xml.etree.ElementTree.Element` in the :mod:`~xml.etree.ElementTree`
|
|
module have been removed. They were deprecated in Python 3.2.
|
|
Use ``iter(x)`` or ``list(x)`` instead of ``x.getchildren()`` and
|
|
``x.iter()`` or ``list(x.iter())`` instead of ``x.getiterator()``.
|
|
(Contributed by Serhiy Storchaka in :issue:`36543`.)
|
|
|
|
* The old :mod:`plistlib` API has been removed, it was deprecated since Python
|
|
3.4. Use the :func:`~plistlib.load`, :func:`~plistlib.loads`, :func:`~plistlib.dump`, and
|
|
:func:`~plistlib.dumps` functions. Additionally, the *use_builtin_types* parameter was
|
|
removed, standard :class:`bytes` objects are always used instead.
|
|
(Contributed by Jon Janzen in :issue:`36409`.)
|
|
|
|
* The C function ``PyGen_NeedsFinalizing`` has been removed. It was not
|
|
documented, tested, or used anywhere within CPython after the implementation
|
|
of :pep:`442`. Patch by Joannah Nanjekye.
|
|
(Contributed by Joannah Nanjekye in :issue:`15088`)
|
|
|
|
* ``base64.encodestring()`` and ``base64.decodestring()``, aliases deprecated
|
|
since Python 3.1, have been removed: use :func:`base64.encodebytes` and
|
|
:func:`base64.decodebytes` instead.
|
|
(Contributed by Victor Stinner in :issue:`39351`.)
|
|
|
|
* ``fractions.gcd()`` function has been removed, it was deprecated since Python
|
|
3.5 (:issue:`22486`): use :func:`math.gcd` instead.
|
|
(Contributed by Victor Stinner in :issue:`39350`.)
|
|
|
|
* The *buffering* parameter of :class:`bz2.BZ2File` has been removed. Since
|
|
Python 3.0, it was ignored and using it emitted a :exc:`DeprecationWarning`.
|
|
Pass an open file object to control how the file is opened.
|
|
(Contributed by Victor Stinner in :issue:`39357`.)
|
|
|
|
* The *encoding* parameter of :func:`json.loads` has been removed.
|
|
As of Python 3.1, it was deprecated and ignored; using it has emitted a
|
|
:exc:`DeprecationWarning` since Python 3.8.
|
|
(Contributed by Inada Naoki in :issue:`39377`)
|
|
|
|
* ``with (await asyncio.lock):`` and ``with (yield from asyncio.lock):`` statements are
|
|
not longer supported, use ``async with lock`` instead. The same is correct for
|
|
``asyncio.Condition`` and ``asyncio.Semaphore``.
|
|
(Contributed by Andrew Svetlov in :issue:`34793`.)
|
|
|
|
* The :func:`sys.getcounts` function, the ``-X showalloccount`` command line
|
|
option and the ``show_alloc_count`` field of the C structure
|
|
:c:type:`PyConfig` have been removed. They required a special Python build by
|
|
defining ``COUNT_ALLOCS`` macro.
|
|
(Contributed by Victor Stinner in :issue:`39489`.)
|
|
|
|
* The ``_field_types`` attribute of the :class:`typing.NamedTuple` class
|
|
has been removed. It was deprecated since Python 3.8. Use
|
|
the ``__annotations__`` attribute instead.
|
|
(Contributed by Serhiy Storchaka in :issue:`40182`.)
|
|
|
|
* The :meth:`symtable.SymbolTable.has_exec` method has been removed. It was
|
|
deprecated since 2006, and only returning ``False`` when it's called.
|
|
(Contributed by Batuhan Taskaya in :issue:`40208`)
|
|
|
|
* The :meth:`asyncio.Task.current_task` and :meth:`asyncio.Task.all_tasks`
|
|
have been removed. They were deprecated since Python 3.7 and you can use
|
|
:func:`asyncio.current_task` and :func:`asyncio.all_tasks` instead.
|
|
(Contributed by Rémi Lapeyre in :issue:`40967`)
|
|
|
|
* The ``unescape()`` method in the :class:`html.parser.HTMLParser` class
|
|
has been removed (it was deprecated since Python 3.4). :func:`html.unescape`
|
|
should be used for converting character references to the corresponding
|
|
unicode characters.
|
|
|
|
|
|
Porting to Python 3.9
|
|
=====================
|
|
|
|
This section lists previously described changes and other bugfixes
|
|
that may require changes to your code.
|
|
|
|
|
|
Changes in the Python API
|
|
-------------------------
|
|
|
|
* :func:`__import__` and :func:`importlib.util.resolve_name` now raise
|
|
:exc:`ImportError` where it previously raised :exc:`ValueError`. Callers
|
|
catching the specific exception type and supporting both Python 3.9 and
|
|
earlier versions will need to catch both using ``except (ImportError, ValueError):``.
|
|
|
|
* The :mod:`venv` activation scripts no longer special-case when
|
|
``__VENV_PROMPT__`` is set to ``""``.
|
|
|
|
* The :meth:`select.epoll.unregister` method no longer ignores the
|
|
:data:`~errno.EBADF` error.
|
|
(Contributed by Victor Stinner in :issue:`39239`.)
|
|
|
|
* The *compresslevel* parameter of :class:`bz2.BZ2File` became keyword-only,
|
|
since the *buffering* parameter has been removed.
|
|
(Contributed by Victor Stinner in :issue:`39357`.)
|
|
|
|
* Simplified AST for subscription. Simple indices will be represented by
|
|
their value, extended slices will be represented as tuples.
|
|
``Index(value)`` will return a ``value`` itself, ``ExtSlice(slices)``
|
|
will return ``Tuple(slices, Load())``.
|
|
(Contributed by Serhiy Storchaka in :issue:`34822`.)
|
|
|
|
* The :mod:`importlib` module now ignores the :envvar:`PYTHONCASEOK`
|
|
environment variable when the :option:`-E` or :option:`-I` command line
|
|
options are being used.
|
|
|
|
* The *encoding* parameter has been added to the classes :class:`ftplib.FTP` and
|
|
:class:`ftplib.FTP_TLS` as a keyword-only parameter, and the default encoding
|
|
is changed from Latin-1 to UTF-8 to follow :rfc:`2640`.
|
|
|
|
* :meth:`asyncio.loop.shutdown_default_executor` has been added to
|
|
:class:`~asyncio.AbstractEventLoop`, meaning alternative event loops that
|
|
inherit from it should have this method defined.
|
|
(Contributed by Kyle Stanley in :issue:`34037`.)
|
|
|
|
* The constant values of future flags in the :mod:`__future__` module
|
|
is updated in order to prevent collision with compiler flags. Previously
|
|
``PyCF_ALLOW_TOP_LEVEL_AWAIT`` was clashing with ``CO_FUTURE_DIVISION``.
|
|
(Contributed by Batuhan Taskaya in :issue:`39562`)
|
|
|
|
* ``array('u')`` now uses ``wchar_t`` as C type instead of ``Py_UNICODE``.
|
|
This change doesn't affect to its behavior because ``Py_UNICODE`` is alias
|
|
of ``wchar_t`` since Python 3.3.
|
|
(Contributed by Inada Naoki in :issue:`34538`.)
|
|
|
|
* The :func:`logging.getLogger` API now returns the root logger when passed
|
|
the name ``'root'``, whereas previously it returned a non-root logger named
|
|
``'root'``. This could affect cases where user code explicitly wants a
|
|
non-root logger named ``'root'``, or instantiates a logger using
|
|
``logging.getLogger(__name__)`` in some top-level module called ``'root.py'``.
|
|
(Contributed by Vinay Sajip in :issue:`37742`.)
|
|
|
|
* Division handling of :class:`~pathlib.PurePath` now returns ``NotImplemented``
|
|
instead of raising a :exc:`TypeError` when passed something other than an
|
|
instance of ``str`` or :class:`~pathlib.PurePath`. This allows creating
|
|
compatible classes that don't inherit from those mentioned types.
|
|
(Contributed by Roger Aiudi in :issue:`34775`).
|
|
|
|
* Starting with Python 3.9.5 the :mod:`ipaddress` module no longer
|
|
accepts any leading zeros in IPv4 address strings. Leading zeros are
|
|
ambiguous and interpreted as octal notation by some libraries. For example
|
|
the legacy function :func:`socket.inet_aton` treats leading zeros as octal
|
|
notatation. glibc implementation of modern :func:`~socket.inet_pton` does
|
|
not accept any leading zeros.
|
|
(Contributed by Christian Heimes in :issue:`36384`).
|
|
|
|
* :func:`codecs.lookup` now normalizes the encoding name the same way as
|
|
:func:`encodings.normalize_encoding`, except that :func:`codecs.lookup` also
|
|
converts the name to lower case. For example, ``"latex+latin1"`` encoding
|
|
name is now normalized to ``"latex_latin1"``.
|
|
(Contributed by Jordon Xu in :issue:`37751`.)
|
|
|
|
|
|
Changes in the C API
|
|
--------------------
|
|
|
|
* Instances of heap-allocated types (such as those created with
|
|
:c:func:`PyType_FromSpec` and similar APIs) hold a reference to their type
|
|
object since Python 3.8. As indicated in the "Changes in the C API" of Python
|
|
3.8, for the vast majority of cases, there should be no side effect but for
|
|
types that have a custom :c:member:`~PyTypeObject.tp_traverse` function,
|
|
ensure that all custom ``tp_traverse`` functions of heap-allocated types
|
|
visit the object's type.
|
|
|
|
Example:
|
|
|
|
.. code-block:: c
|
|
|
|
int
|
|
foo_traverse(foo_struct *self, visitproc visit, void *arg) {
|
|
// Rest of the traverse function
|
|
#if PY_VERSION_HEX >= 0x03090000
|
|
// This was not needed before Python 3.9 (Python issue 35810 and 40217)
|
|
Py_VISIT(Py_TYPE(self));
|
|
#endif
|
|
}
|
|
|
|
If your traverse function delegates to ``tp_traverse`` of its base class
|
|
(or another type), ensure that ``Py_TYPE(self)`` is visited only once.
|
|
Note that only heap types are expected to visit the type in ``tp_traverse``.
|
|
|
|
For example, if your ``tp_traverse`` function includes:
|
|
|
|
.. code-block:: c
|
|
|
|
base->tp_traverse(self, visit, arg)
|
|
|
|
then add:
|
|
|
|
.. code-block:: c
|
|
|
|
#if PY_VERSION_HEX >= 0x03090000
|
|
// This was not needed before Python 3.9 (Python issue 35810 and 40217)
|
|
if (base->tp_flags & Py_TPFLAGS_HEAPTYPE) {
|
|
// a heap type's tp_traverse already visited Py_TYPE(self)
|
|
} else {
|
|
Py_VISIT(Py_TYPE(self));
|
|
}
|
|
#else
|
|
|
|
(See :issue:`35810` and :issue:`40217` for more information.)
|
|
|
|
* The functions ``PyEval_CallObject``, ``PyEval_CallFunction``,
|
|
``PyEval_CallMethod`` and ``PyEval_CallObjectWithKeywords`` are deprecated.
|
|
Use :c:func:`PyObject_Call` and its variants instead.
|
|
(See more details in :issue:`29548`.)
|
|
|
|
CPython bytecode changes
|
|
------------------------
|
|
|
|
* The :opcode:`LOAD_ASSERTION_ERROR` opcode was added for handling the
|
|
:keyword:`assert` statement. Previously, the assert statement would not work
|
|
correctly if the :exc:`AssertionError` exception was being shadowed.
|
|
(Contributed by Zackery Spytz in :issue:`34880`.)
|
|
|
|
* The :opcode:`COMPARE_OP` opcode was split into four distinct instructions:
|
|
|
|
* ``COMPARE_OP`` for rich comparisons
|
|
* ``IS_OP`` for 'is' and 'is not' tests
|
|
* ``CONTAINS_OP`` for 'in' and 'not in' tests
|
|
* ``JUMP_IF_NOT_EXC_MATCH`` for checking exceptions in 'try-except'
|
|
statements.
|
|
|
|
(Contributed by Mark Shannon in :issue:`39156`.)
|
|
|
|
|
|
Build Changes
|
|
=============
|
|
|
|
* Added ``--with-platlibdir`` option to the ``configure`` script: name of the
|
|
platform-specific library directory, stored in the new :attr:`sys.platlibdir`
|
|
attribute. See :attr:`sys.platlibdir` attribute for more information.
|
|
(Contributed by Jan Matějek, Matěj Cepl, Charalampos Stratakis
|
|
and Victor Stinner in :issue:`1294959`.)
|
|
|
|
* The ``COUNT_ALLOCS`` special build macro has been removed.
|
|
(Contributed by Victor Stinner in :issue:`39489`.)
|
|
|
|
* On non-Windows platforms, the :c:func:`setenv` and :c:func:`unsetenv`
|
|
functions are now required to build Python.
|
|
(Contributed by Victor Stinner in :issue:`39395`.)
|
|
|
|
* On non-Windows platforms, creating ``bdist_wininst`` installers is now
|
|
officially unsupported. (See :issue:`10945` for more details.)
|
|
|
|
* When building Python on macOS from source, ``_tkinter`` now links with
|
|
non-system Tcl and Tk frameworks if they are installed in
|
|
``/Library/Frameworks``, as had been the case on older releases
|
|
of macOS. If a macOS SDK is explicitly configured, by using
|
|
``--enable-universalsdk=`` or ``-isysroot``, only the SDK itself is
|
|
searched. The default behavior can still be overridden with
|
|
``--with-tcltk-includes`` and ``--with-tcltk-libs``.
|
|
(Contributed by Ned Deily in :issue:`34956`.)
|
|
|
|
* Python can now be built for Windows 10 ARM64.
|
|
(Contributed by Steve Dower in :issue:`33125`.)
|
|
|
|
* Some individual tests are now skipped when ``--pgo`` is used. The tests
|
|
in question increased the PGO task time significantly and likely
|
|
didn't help improve optimization of the final executable. This
|
|
speeds up the task by a factor of about 15x. Running the full unit test
|
|
suite is slow. This change may result in a slightly less optimized build
|
|
since not as many code branches will be executed. If you are willing to
|
|
wait for the much slower build, the old behavior can be restored using
|
|
``./configure [..] PROFILE_TASK="-m test --pgo-extended"``. We make no
|
|
guarantees as to which PGO task set produces a faster build. Users who care
|
|
should run their own relevant benchmarks as results can depend on the
|
|
environment, workload, and compiler tool chain.
|
|
(See :issue:`36044` and :issue:`37707` for more details.)
|
|
|
|
|
|
C API Changes
|
|
=============
|
|
|
|
New Features
|
|
------------
|
|
|
|
* :pep:`573`: Added :c:func:`PyType_FromModuleAndSpec` to associate
|
|
a module with a class; :c:func:`PyType_GetModule` and
|
|
:c:func:`PyType_GetModuleState` to retrieve the module and its state; and
|
|
:c:data:`PyCMethod` and :c:data:`METH_METHOD` to allow a method to
|
|
access the class it was defined in.
|
|
(Contributed by Marcel Plch and Petr Viktorin in :issue:`38787`.)
|
|
|
|
* Added :c:func:`PyFrame_GetCode` function: get a frame code.
|
|
Added :c:func:`PyFrame_GetBack` function: get the frame next outer frame.
|
|
(Contributed by Victor Stinner in :issue:`40421`.)
|
|
|
|
* Added :c:func:`PyFrame_GetLineNumber` to the limited C API.
|
|
(Contributed by Victor Stinner in :issue:`40421`.)
|
|
|
|
* Added :c:func:`PyThreadState_GetInterpreter` and
|
|
:c:func:`PyInterpreterState_Get` functions to get the interpreter.
|
|
Added :c:func:`PyThreadState_GetFrame` function to get the current frame of a
|
|
Python thread state.
|
|
Added :c:func:`PyThreadState_GetID` function: get the unique identifier of a
|
|
Python thread state.
|
|
(Contributed by Victor Stinner in :issue:`39947`.)
|
|
|
|
* Added a new public :c:func:`PyObject_CallNoArgs` function to the C API, which
|
|
calls a callable Python object without any arguments. It is the most efficient
|
|
way to call a callable Python object without any argument.
|
|
(Contributed by Victor Stinner in :issue:`37194`.)
|
|
|
|
* Changes in the limited C API (if ``Py_LIMITED_API`` macro is defined):
|
|
|
|
* Provide :c:func:`Py_EnterRecursiveCall` and :c:func:`Py_LeaveRecursiveCall`
|
|
as regular functions for the limited API. Previously, there were defined as
|
|
macros, but these macros didn't compile with the limited C API which cannot
|
|
access ``PyThreadState.recursion_depth`` field (the structure is opaque in
|
|
the limited C API).
|
|
|
|
* ``PyObject_INIT()`` and ``PyObject_INIT_VAR()`` become regular "opaque"
|
|
function to hide implementation details.
|
|
|
|
(Contributed by Victor Stinner in :issue:`38644` and :issue:`39542`.)
|
|
|
|
* The :c:func:`PyModule_AddType` function is added to help adding a type
|
|
to a module.
|
|
(Contributed by Dong-hee Na in :issue:`40024`.)
|
|
|
|
* Added the functions :c:func:`PyObject_GC_IsTracked` and
|
|
:c:func:`PyObject_GC_IsFinalized` to the public API to allow to query if
|
|
Python objects are being currently tracked or have been already finalized by
|
|
the garbage collector respectively.
|
|
(Contributed by Pablo Galindo Salgado in :issue:`40241`.)
|
|
|
|
* Added :c:func:`_PyObject_FunctionStr` to get a user-friendly string
|
|
representation of a function-like object.
|
|
(Patch by Jeroen Demeyer in :issue:`37645`.)
|
|
|
|
* Added :c:func:`PyObject_CallOneArg` for calling an object with one
|
|
positional argument
|
|
(Patch by Jeroen Demeyer in :issue:`37483`.)
|
|
|
|
|
|
Porting to Python 3.9
|
|
---------------------
|
|
|
|
* ``PyInterpreterState.eval_frame`` (:pep:`523`) now requires a new mandatory
|
|
*tstate* parameter (``PyThreadState*``).
|
|
(Contributed by Victor Stinner in :issue:`38500`.)
|
|
|
|
* Extension modules: :c:member:`~PyModuleDef.m_traverse`,
|
|
:c:member:`~PyModuleDef.m_clear` and :c:member:`~PyModuleDef.m_free`
|
|
functions of :c:type:`PyModuleDef` are no longer called if the module state
|
|
was requested but is not allocated yet. This is the case immediately after
|
|
the module is created and before the module is executed
|
|
(:c:data:`Py_mod_exec` function). More precisely, these functions are not called
|
|
if :c:member:`~PyModuleDef.m_size` is greater than 0 and the module state (as
|
|
returned by :c:func:`PyModule_GetState`) is ``NULL``.
|
|
|
|
Extension modules without module state (``m_size <= 0``) are not affected.
|
|
|
|
* If :c:func:`Py_AddPendingCall` is called in a subinterpreter, the function is
|
|
now scheduled to be called from the subinterpreter, rather than being called
|
|
from the main interpreter. Each subinterpreter now has its own list of
|
|
scheduled calls.
|
|
(Contributed by Victor Stinner in :issue:`39984`.)
|
|
|
|
* The Windows registry is no longer used to initialize :data:`sys.path` when
|
|
the ``-E`` option is used (if :c:member:`PyConfig.use_environment` is set to
|
|
``0``). This is significant when embedding Python on Windows.
|
|
(Contributed by Zackery Spytz in :issue:`8901`.)
|
|
|
|
* The global variable :c:data:`PyStructSequence_UnnamedField` is now a constant
|
|
and refers to a constant string.
|
|
(Contributed by Serhiy Storchaka in :issue:`38650`.)
|
|
|
|
* The :c:type:`PyGC_Head` structure is now opaque. It is only defined in the
|
|
internal C API (``pycore_gc.h``).
|
|
(Contributed by Victor Stinner in :issue:`40241`.)
|
|
|
|
* The ``Py_UNICODE_COPY``, ``Py_UNICODE_FILL``, ``PyUnicode_WSTR_LENGTH``,
|
|
:c:func:`PyUnicode_FromUnicode`, :c:func:`PyUnicode_AsUnicode`,
|
|
``_PyUnicode_AsUnicode``, and :c:func:`PyUnicode_AsUnicodeAndSize` are
|
|
marked as deprecated in C. They have been deprecated by :pep:`393` since
|
|
Python 3.3.
|
|
(Contributed by Inada Naoki in :issue:`36346`.)
|
|
|
|
* The :c:func:`Py_FatalError` function is replaced with a macro which logs
|
|
automatically the name of the current function, unless the
|
|
``Py_LIMITED_API`` macro is defined.
|
|
(Contributed by Victor Stinner in :issue:`39882`.)
|
|
|
|
* The vectorcall protocol now requires that the caller passes only strings as
|
|
keyword names. (See :issue:`37540` for more information.)
|
|
|
|
* Implementation details of a number of macros and functions are now hidden:
|
|
|
|
* :c:func:`PyObject_IS_GC` macro was converted to a function.
|
|
|
|
* The :c:func:`PyObject_NEW` macro becomes an alias to the
|
|
:c:func:`PyObject_New` macro, and the :c:func:`PyObject_NEW_VAR` macro
|
|
becomes an alias to the :c:func:`PyObject_NewVar` macro. They no longer
|
|
access directly the :c:member:`PyTypeObject.tp_basicsize` member.
|
|
|
|
* :c:func:`PyType_HasFeature` now always calls :c:func:`PyType_GetFlags`.
|
|
Previously, it accessed directly the :c:member:`PyTypeObject.tp_flags`
|
|
member when the limited C API was not used.
|
|
|
|
* :c:func:`PyObject_GET_WEAKREFS_LISTPTR` macro was converted to a function:
|
|
the macro accessed directly the :c:member:`PyTypeObject.tp_weaklistoffset`
|
|
member.
|
|
|
|
* :c:func:`PyObject_CheckBuffer` macro was converted to a function: the macro
|
|
accessed directly the :c:member:`PyTypeObject.tp_as_buffer` member.
|
|
|
|
* :c:func:`PyIndex_Check` is now always declared as an opaque function to hide
|
|
implementation details: removed the ``PyIndex_Check()`` macro. The macro accessed
|
|
directly the :c:member:`PyTypeObject.tp_as_number` member.
|
|
|
|
(See :issue:`40170` for more details.)
|
|
|
|
Removed
|
|
-------
|
|
|
|
* Excluded ``PyFPE_START_PROTECT()`` and ``PyFPE_END_PROTECT()`` macros of
|
|
``pyfpe.h`` from the limited C API.
|
|
(Contributed by Victor Stinner in :issue:`38835`.)
|
|
|
|
* The ``tp_print`` slot of :ref:`PyTypeObject <type-structs>` has been removed.
|
|
It was used for printing objects to files in Python 2.7 and before. Since
|
|
Python 3.0, it has been ignored and unused.
|
|
(Contributed by Jeroen Demeyer in :issue:`36974`.)
|
|
|
|
* Changes in the limited C API (if ``Py_LIMITED_API`` macro is defined):
|
|
|
|
* Excluded the following functions from the limited C API:
|
|
|
|
* ``PyThreadState_DeleteCurrent()``
|
|
(Contributed by Joannah Nanjekye in :issue:`37878`.)
|
|
* ``_Py_CheckRecursionLimit``
|
|
* ``_Py_NewReference()``
|
|
* ``_Py_ForgetReference()``
|
|
* ``_PyTraceMalloc_NewReference()``
|
|
* ``_Py_GetRefTotal()``
|
|
* The trashcan mechanism which never worked in the limited C API.
|
|
* ``PyTrash_UNWIND_LEVEL``
|
|
* ``Py_TRASHCAN_BEGIN_CONDITION``
|
|
* ``Py_TRASHCAN_BEGIN``
|
|
* ``Py_TRASHCAN_END``
|
|
* ``Py_TRASHCAN_SAFE_BEGIN``
|
|
* ``Py_TRASHCAN_SAFE_END``
|
|
|
|
* Moved following functions and definitions to the internal C API:
|
|
|
|
* ``_PyDebug_PrintTotalRefs()``
|
|
* ``_Py_PrintReferences()``
|
|
* ``_Py_PrintReferenceAddresses()``
|
|
* ``_Py_tracemalloc_config``
|
|
* ``_Py_AddToAllObjects()`` (specific to ``Py_TRACE_REFS`` build)
|
|
|
|
(Contributed by Victor Stinner in :issue:`38644` and :issue:`39542`.)
|
|
|
|
* Removed ``_PyRuntime.getframe`` hook and removed ``_PyThreadState_GetFrame``
|
|
macro which was an alias to ``_PyRuntime.getframe``. They were only exposed
|
|
by the internal C API. Removed also ``PyThreadFrameGetter`` type.
|
|
(Contributed by Victor Stinner in :issue:`39946`.)
|
|
|
|
* Removed the following functions from the C API. Call :c:func:`PyGC_Collect`
|
|
explicitly to clear all free lists.
|
|
(Contributed by Inada Naoki and Victor Stinner in :issue:`37340`,
|
|
:issue:`38896` and :issue:`40428`.)
|
|
|
|
* ``PyAsyncGen_ClearFreeLists()``
|
|
* ``PyContext_ClearFreeList()``
|
|
* ``PyDict_ClearFreeList()``
|
|
* ``PyFloat_ClearFreeList()``
|
|
* ``PyFrame_ClearFreeList()``
|
|
* ``PyList_ClearFreeList()``
|
|
* ``PyMethod_ClearFreeList()`` and ``PyCFunction_ClearFreeList()``:
|
|
the free lists of bound method objects have been removed.
|
|
* ``PySet_ClearFreeList()``: the set free list has been removed
|
|
in Python 3.4.
|
|
* ``PyTuple_ClearFreeList()``
|
|
* ``PyUnicode_ClearFreeList()``: the Unicode free list has been removed in
|
|
Python 3.3.
|
|
|
|
* Removed ``_PyUnicode_ClearStaticStrings()`` function.
|
|
(Contributed by Victor Stinner in :issue:`39465`.)
|
|
|
|
* Removed ``Py_UNICODE_MATCH``. It has been deprecated by :pep:`393`, and
|
|
broken since Python 3.3. The :c:func:`PyUnicode_Tailmatch` function can be
|
|
used instead.
|
|
(Contributed by Inada Naoki in :issue:`36346`.)
|
|
|
|
* Cleaned header files of interfaces defined but with no implementation.
|
|
The public API symbols being removed are:
|
|
``_PyBytes_InsertThousandsGroupingLocale``,
|
|
``_PyBytes_InsertThousandsGrouping``, ``_Py_InitializeFromArgs``,
|
|
``_Py_InitializeFromWideArgs``, ``_PyFloat_Repr``, ``_PyFloat_Digits``,
|
|
``_PyFloat_DigitsInit``, ``PyFrame_ExtendStack``, ``_PyAIterWrapper_Type``,
|
|
``PyNullImporter_Type``, ``PyCmpWrapper_Type``, ``PySortWrapper_Type``,
|
|
``PyNoArgsFunction``.
|
|
(Contributed by Pablo Galindo Salgado in :issue:`39372`.)
|
|
|
|
Notable changes in Python 3.9.1
|
|
===============================
|
|
|
|
typing
|
|
------
|
|
|
|
The behavior of :class:`typing.Literal` was changed to conform with :pep:`586`
|
|
and to match the behavior of static type checkers specified in the PEP.
|
|
|
|
1. ``Literal`` now de-duplicates parameters.
|
|
2. Equality comparisons between ``Literal`` objects are now order independent.
|
|
3. ``Literal`` comparisons now respect types. For example,
|
|
``Literal[0] == Literal[False]`` previously evaluated to ``True``. It is
|
|
now ``False``. To support this change, the internally used type cache now
|
|
supports differentiating types.
|
|
4. ``Literal`` objects will now raise a :exc:`TypeError` exception during
|
|
equality comparisons if any of their parameters are not :term:`hashable`.
|
|
Note that declaring ``Literal`` with mutable parameters will not throw
|
|
an error::
|
|
|
|
>>> from typing import Literal
|
|
>>> Literal[{0}]
|
|
>>> Literal[{0}] == Literal[{False}]
|
|
Traceback (most recent call last):
|
|
File "<stdin>", line 1, in <module>
|
|
TypeError: unhashable type: 'set'
|
|
|
|
(Contributed by Yurii Karabas in :issue:`42345`.)
|
|
|
|
macOS 11.0 (Big Sur) and Apple Silicon Mac support
|
|
--------------------------------------------------
|
|
|
|
As of 3.9.1, Python now fully supports building and running on macOS 11.0
|
|
(Big Sur) and on Apple Silicon Macs (based on the ``ARM64`` architecture).
|
|
A new universal build variant, ``universal2``, is now available to natively
|
|
support both ``ARM64`` and ``Intel 64`` in one set of executables. Binaries
|
|
can also now be built on current versions of macOS to be deployed on a range
|
|
of older macOS versions (tested to 10.9) while making some newer OS
|
|
functions and options conditionally available based on the operating system
|
|
version in use at runtime ("weaklinking").
|
|
|
|
(Contributed by Ronald Oussoren and Lawrence D'Anna in :issue:`41100`.)
|
|
|
|
Notable changes in Python 3.9.2
|
|
===============================
|
|
|
|
collections.abc
|
|
---------------
|
|
|
|
:class:`collections.abc.Callable` generic now flattens type parameters, similar
|
|
to what :data:`typing.Callable` currently does. This means that
|
|
``collections.abc.Callable[[int, str], str]`` will have ``__args__`` of
|
|
``(int, str, str)``; previously this was ``([int, str], str)``. To allow this
|
|
change, :class:`types.GenericAlias` can now be subclassed, and a subclass will
|
|
be returned when subscripting the :class:`collections.abc.Callable` type.
|
|
Code which accesses the arguments via :func:`typing.get_args` or ``__args__``
|
|
need to account for this change. A :exc:`DeprecationWarning` may be emitted for
|
|
invalid forms of parameterizing :class:`collections.abc.Callable` which may have
|
|
passed silently in Python 3.9.1. This :exc:`DeprecationWarning` will
|
|
become a :exc:`TypeError` in Python 3.10.
|
|
(Contributed by Ken Jin in :issue:`42195`.)
|
|
|
|
urllib.parse
|
|
------------
|
|
|
|
Earlier Python versions allowed using both ``;`` and ``&`` as
|
|
query parameter separators in :func:`urllib.parse.parse_qs` and
|
|
:func:`urllib.parse.parse_qsl`. Due to security concerns, and to conform with
|
|
newer W3C recommendations, this has been changed to allow only a single
|
|
separator key, with ``&`` as the default. This change also affects
|
|
:func:`cgi.parse` and :func:`cgi.parse_multipart` as they use the affected
|
|
functions internally. For more details, please see their respective
|
|
documentation.
|
|
(Contributed by Adam Goldschmidt, Senthil Kumaran and Ken Jin in :issue:`42967`.)
|
|
|
|
Notable changes in Python 3.9.3
|
|
===============================
|
|
|
|
A security fix alters the :class:`ftplib.FTP` behavior to not trust the
|
|
IPv4 address sent from the remote server when setting up a passive data
|
|
channel. We reuse the ftp server IP address instead. For unusual code
|
|
requiring the old behavior, set a ``trust_server_pasv_ipv4_address``
|
|
attribute on your FTP instance to ``True``. (See :issue:`43285`)
|
|
|
|
Notable changes in Python 3.9.5
|
|
===============================
|
|
|
|
urllib.parse
|
|
------------
|
|
|
|
The presence of newline or tab characters in parts of a URL allows for some
|
|
forms of attacks. Following the WHATWG specification that updates :rfc:`3986`,
|
|
ASCII newline ``\n``, ``\r`` and tab ``\t`` characters are stripped from the
|
|
URL by the parser in :mod:`urllib.parse` preventing such attacks. The removal
|
|
characters are controlled by a new module level variable
|
|
``urllib.parse._UNSAFE_URL_BYTES_TO_REMOVE``. (See :issue:`43882`)
|
|
|