Doc/whatsnew/3.12.rst
What's New In Python 3.12
:Editor: Adam Turner
.. Rules for maintenance:
Anyone can add text to this document. Do not spend very much time on the wording of your changes, because your text will probably 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 I consider too small or esoteric to include. If such a change is added to the text, I'll just remove it. (This is another reason you shouldn't spend too much time on writing your addition.)
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 issue number as a comment:
XXX Describe the transmogrify() function added to the socket
module.
(Contributed by P.Y. Developer in :gh:12345.)
This saves the maintainer the effort of going through the VCS log when researching a change.
This article explains the new features in Python 3.12, compared to 3.11.
Python 3.12 was released on October 2, 2023.
For full details, see the :ref:changelog <changelog>.
.. seealso::
:pep:693 -- Python 3.12 Release Schedule
.. This section singles out the most important changes in Python 3.12. Brevity is key.
Python 3.12 is a stable release of the Python programming language,
with a mix of changes to the language and the standard library.
The library changes focus on cleaning up deprecated APIs, usability, and correctness.
Of note, the :mod:!distutils package has been removed from the standard library.
Filesystem support in :mod:os and :mod:pathlib has seen a number of improvements,
and several modules have better performance.
The language changes focus on usability,
as :term:f-strings <f-string> have had many limitations removed
and 'Did you mean ...' suggestions continue to improve.
The new :ref:type parameter syntax <whatsnew312-pep695>
and :keyword:type statement improve ergonomics for using :term:generic types <generic type> and :term:type aliases <type alias> with static type checkers.
This article doesn't attempt to provide a complete specification of all new features,
but instead gives a convenient overview.
For full details, you should refer to the documentation,
such as the :ref:Library Reference <library-index>
and :ref:Language Reference <reference-index>.
If you want to understand the complete implementation and design rationale for a change,
refer to the PEP for a particular new feature;
but note that PEPs usually are not kept up-to-date
once a feature has been fully implemented.
.. PEP-sized items next.
New syntax features:
PEP 695 <whatsnew312-pep695>, type parameter syntax and the :keyword:type statementNew grammar features:
PEP 701 <whatsnew312-pep701>, :term:f-strings <f-string> in the grammarInterpreter improvements:
PEP 684 <whatsnew312-pep684>, a unique per-interpreter :term:GIL <global interpreter lock>PEP 669 <whatsnew312-pep669>, low impact monitoringImproved 'Did you mean ...' suggestions <improved error messages_>_
for :exc:NameError, :exc:ImportError, and :exc:SyntaxError exceptionsPython data model improvements:
PEP 688 <whatsnew312-pep688>, using the :ref:buffer protocol <bufferobjects> from PythonSignificant improvements in the standard library:
pathlib.Path class now supports subclassingos module received several improvements for Windows supportcommand-line interface <sqlite3-cli> has been added to the
:mod:sqlite3 moduleisinstance checks against :func:runtime-checkable protocols <typing.runtime_checkable> enjoy a speed up of between two and 20 timesasyncio package has had a number of performance improvements,
with some benchmarks showing a 75% speed up.command-line interface <uuid-cli> has been added to the
:mod:uuid modulePEP 701 <whatsnew312-pep701>,
producing tokens via the :mod:tokenize module is up to 64% faster.Security improvements:
hashlib implementations of
SHA1, SHA3, SHA2-384, SHA2-512, and MD5 with formally verified code from the
HACL* <https://github.com/hacl-star/hacl-star/>__ project.
These builtin implementations remain as fallbacks that are only used when
OpenSSL does not provide them.C API improvements:
PEP 697 <whatsnew312-pep697>, unstable C API tierPEP 683 <whatsnew312-pep683>, immortal objectsCPython implementation improvements:
PEP 709 <whatsnew312-pep709>, comprehension inliningCPython support <perf_profiling> for the Linux perf profilerNew typing features:
PEP 692 <whatsnew312-pep692>, using :class:~typing.TypedDict to
annotate :term:**kwargs <argument>PEP 698 <whatsnew312-pep698>, :func:typing.override decoratorImportant deprecations, removals or restrictions:
:pep:623: Remove wstr from Unicode objects in Python's C API,
reducing the size of every :class:str object by at least 8 bytes.
:pep:632: Remove the :mod:!distutils package.
See :pep:the migration guide <0632#migration-advice>
for advice replacing the APIs it provided.
The third-party Setuptools <https://setuptools.pypa.io/en/latest/deprecated/distutils-legacy.html>__
package continues to provide :mod:!distutils,
if you still require it in Python 3.12 and beyond.
:gh:95299: Do not pre-install setuptools in virtual environments
created with :mod:venv.
This means that distutils, setuptools, pkg_resources,
and easy_install will no longer available by default; to access these
run pip install setuptools in the :ref:activated <venv-explanation>
virtual environment.
The :mod:!asynchat, :mod:!asyncore, and :mod:!imp modules have been
removed, along with several :class:unittest.TestCase
method aliases <unittest-TestCase-removed-aliases_>_.
.. _whatsnew312-pep695:
Generic classes and functions under :pep:484 were declared using a verbose syntax
that left the scope of type parameters unclear and required explicit declarations of
variance.
:pep:695 introduces a new, more compact and explicit way to create
:ref:generic classes <generic-classes> and :ref:functions <generic-functions>::
def max[T](args: Iterable[T]) -> T: ...
class list[T]: def getitem(self, index: int, /) -> T: ...
def append(self, element: T) -> None:
...
In addition, the PEP introduces a new way to declare :ref:type aliases <type-aliases>
using the :keyword:type statement, which creates an instance of
:class:~typing.TypeAliasType::
type Point = tuple[float, float]
Type aliases can also be :ref:generic <generic-type-aliases>::
type Point[T] = tuple[T, T]
The new syntax allows declaring :class:~typing.TypeVarTuple
and :class:~typing.ParamSpec parameters, as well as :class:~typing.TypeVar
parameters with bounds or constraints::
type IntFunc[**P] = Callable[P, int] # ParamSpec type LabeledTuple[*Ts] = tuple[str, *Ts] # TypeVarTuple type HashableSequence[T: Hashable] = Sequence[T] # TypeVar with bound type IntOrStrSequence[T: (int, str)] = Sequence[T] # TypeVar with constraints
The value of type aliases and the bound and constraints of type variables
created through this syntax are evaluated only on demand (see
:ref:lazy evaluation <lazy-evaluation>). This means type aliases are able to
refer to other types defined later in the file.
Type parameters declared through a type parameter list are visible within the
scope of the declaration and any nested scopes, but not in the outer scope. For
example, they can be used in the type annotations for the methods of a generic
class or in the class body. However, they cannot be used in the module scope after
the class is defined. See :ref:type-params for a detailed description of the
runtime semantics of type parameters.
In order to support these scoping semantics, a new kind of scope is introduced,
the :ref:annotation scope <annotation-scopes>. Annotation scopes behave for the
most part like function scopes, but interact differently with enclosing class scopes.
In Python 3.13, :term:annotations <annotation> will also be evaluated in
annotation scopes.
See :pep:695 for more details.
(PEP written by Eric Traut. Implementation by Jelle Zijlstra, Eric Traut,
and others in :gh:103764.)
.. _whatsnew312-pep701:
:pep:701 lifts some restrictions on the usage of :term:f-strings <f-string>.
Expression components inside f-strings can now be any valid Python expression,
including strings reusing the same quote as the containing f-string,
multi-line expressions, comments, backslashes, and unicode escape sequences.
Let's cover these in detail:
Quote reuse: in Python 3.11, reusing the same quotes as the enclosing f-string
raises a :exc:SyntaxError, forcing the user to either use other available
quotes (like using double quotes or triple quotes if the f-string uses single
quotes). In Python 3.12, you can now do things like this:
songs = ['Take me back to Eden', 'Alkaline', 'Ascensionism'] f"This is the playlist: {", ".join(songs)}" 'This is the playlist: Take me back to Eden, Alkaline, Ascensionism'
Note that before this change there was no explicit limit in how f-strings can be nested, but the fact that string quotes cannot be reused inside the expression component of f-strings made it impossible to nest f-strings arbitrarily. In fact, this is the most nested f-string that could be written:
f"""{f'''{f'{f"{1+1}"}'}'''}""" '2'
As now f-strings can contain any valid Python expression inside expression components, it is now possible to nest f-strings arbitrarily:
f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" '2'
Multi-line expressions and comments: In Python 3.11, f-string expressions must be defined in a single line, even if the expression within the f-string could normally span multiple lines (like literal lists being defined over multiple lines), making them harder to read. In Python 3.12 you can now define f-strings spanning multiple lines, and add inline comments:
f"This is the playlist: {", ".join([ ... 'Take me back to Eden', # My, my, those eyes like fire ... 'Alkaline', # Not acid nor alkaline ... 'Ascensionism' # Take to the broken skies at last ... ])}" 'This is the playlist: Take me back to Eden, Alkaline, Ascensionism'
Backslashes and unicode characters: before Python 3.12 f-string expressions
couldn't contain any \ character. This also affected unicode :ref:escape sequences <escape-sequences> (such as \N{snowman}) as these contain
the \N part that previously could not be part of expression components of
f-strings. Now, you can define expressions like this:
print(f"This is the playlist: {"\n".join(songs)}") This is the playlist: Take me back to Eden Alkaline Ascensionism print(f"This is the playlist: {"\N{BLACK HEART SUIT}".join(songs)}") This is the playlist: Take me back to Eden♥Alkaline♥Ascensionism
See :pep:701 for more details.
As a positive side-effect of how this feature has been implemented (by parsing f-strings
with :pep:the PEG parser <617>), now error messages for f-strings are more precise
and include the exact location of the error. For example, in Python 3.11, the following
f-string raises a :exc:SyntaxError:
.. code-block:: python
>>> my_string = f"{x z y}" + f"{1 + 1}"
File "<stdin>", line 1
(x z y)
^^^
SyntaxError: f-string: invalid syntax. Perhaps you forgot a comma?
but the error message doesn't include the exact location of the error within the line and also has the expression artificially surrounded by parentheses. In Python 3.12, as f-strings are parsed with the PEG parser, error messages can be more precise and show the entire line:
.. code-block:: python
>>> my_string = f"{x z y}" + f"{1 + 1}"
File "<stdin>", line 1
my_string = f"{x z y}" + f"{1 + 1}"
^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?
(Contributed by Pablo Galindo, Batuhan Taskaya, Lysandros Nikolaou, Cristián
Maureira-Fredes and Marta Gómez in :gh:102856. PEP written by Pablo Galindo,
Batuhan Taskaya, Lysandros Nikolaou and Marta Gómez).
.. _whatsnew312-pep684:
:pep:684 introduces a per-interpreter :term:GIL <global interpreter lock>,
so that sub-interpreters may now be created with a unique GIL per interpreter.
This allows Python programs to take full advantage of multiple CPU
cores. This is currently only available through the C-API,
though a Python API is :pep:anticipated for 3.13 <554>.
Use the new :c:func:Py_NewInterpreterFromConfig function to
create an interpreter with its own GIL:
.. code-block:: c
PyInterpreterConfig config = { .check_multi_interp_extensions = 1, .gil = PyInterpreterConfig_OWN_GIL, }; PyThreadState tstate = NULL; PyStatus status = Py_NewInterpreterFromConfig(&tstate, &config); if (PyStatus_Exception(status)) { return -1; } / The new interpreter is now active in the current thread. */
For further examples how to use the C-API for sub-interpreters with a
per-interpreter GIL, see Modules/_xxsubinterpretersmodule.c.
(Contributed by Eric Snow in :gh:104210, etc.)
.. _whatsnew312-pep669:
:pep:669 defines a new :mod:API <sys.monitoring> for profilers,
debuggers, and other tools to monitor events in CPython.
It covers a wide range of events, including calls,
returns, lines, exceptions, jumps, and more.
This means that you only pay for what you use, providing support
for near-zero overhead debuggers and coverage tools.
See :mod:sys.monitoring for details.
(Contributed by Mark Shannon in :gh:103082.)
.. _whatsnew312-pep688:
:pep:688 introduces a way to use the :ref:buffer protocol <bufferobjects>
from Python code. Classes that implement the :meth:~object.__buffer__ method
are now usable as buffer types.
The new :class:collections.abc.Buffer ABC provides a standard
way to represent buffer objects, for example in type annotations.
The new :class:inspect.BufferFlags enum represents the flags that
can be used to customize buffer creation.
(Contributed by Jelle Zijlstra in :gh:102500.)
.. _whatsnew312-pep709:
Dictionary, list, and set comprehensions are now inlined, rather than creating a
new single-use function object for each execution of the comprehension. This
speeds up execution of a comprehension by up to two times.
See :pep:709 for further details.
Comprehension iteration variables remain isolated and don't overwrite a variable of the same name in the outer scope, nor are they visible after the comprehension. Inlining does result in a few visible behavior changes:
symtable module will no longer produce child symbol tables for each
comprehension; instead, the comprehension's locals will be included in the
parent function's symbol table.locals inside a comprehension now includes variables
from outside the comprehension, and no longer includes the synthetic .0
variable for the comprehension "argument".locals() (e.g. [k for k in locals()]) may see "RuntimeError: dictionary changed size during iteration"
when run under tracing (e.g. code coverage measurement). This is the same
behavior already seen in e.g. for k in locals():. To avoid the error, first
create a list of keys to iterate over: keys = list(locals()); [k for k in keys].(Contributed by Carl Meyer and Vladimir Matveev in :pep:709.)
Modules from the standard library are now potentially suggested as part of
the error messages displayed by the interpreter when a :exc:NameError is
raised to the top level. (Contributed by Pablo Galindo in :gh:98254.)
sys.version_info Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'sys' is not defined. Did you forget to import 'sys'?
Improve the error suggestion for :exc:NameError exceptions for instances.
Now if a :exc:NameError is raised in a method and the instance has an
attribute that's exactly equal to the name in the exception, the suggestion
will include self.<NAME> instead of the closest match in the method
scope. (Contributed by Pablo Galindo in :gh:99139.)
class A: ... def init(self): ... self.blech = 1 ... ... def foo(self): ... somethin = blech ... A().foo() Traceback (most recent call last): File "<stdin>", line 1 somethin = blech ^^^^^ NameError: name 'blech' is not defined. Did you mean: 'self.blech'?
Improve the :exc:SyntaxError error message when the user types import x from y instead of from y import x. (Contributed by Pablo Galindo in :gh:98931.)
import a.y.z from b.y.z Traceback (most recent call last): File "<stdin>", line 1 import a.y.z from b.y.z ^^^^^^^^^^^^^^^^^^^^^^^ SyntaxError: Did you mean to use 'from ... import ...' instead?
:exc:ImportError exceptions raised from failed from <module> import <name> statements now include suggestions for the value of <name> based on the
available names in <module>. (Contributed by Pablo Galindo in :gh:91058.)
from collections import chainmap Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name 'chainmap' from 'collections'. Did you mean: 'ChainMap'?
This section covers major changes affecting :pep:type hints <484> and
the :mod:typing module.
.. _whatsnew312-pep692:
TypedDict for more precise **kwargs typingTyping **kwargs in a function signature as introduced by :pep:484 allowed
for valid annotations only in cases where all of the **kwargs were of the
same type.
:pep:692 specifies a more precise way of typing **kwargs by relying on
typed dictionaries::
from typing import TypedDict, Unpack
class Movie(TypedDict): name: str year: int
def foo(**kwargs: Unpack[Movie]): ...
See :pep:692 for more details.
(Contributed by Franek Magiera in :gh:103629.)
.. _whatsnew312-pep698:
A new decorator :func:typing.override has been added to the :mod:typing
module. It indicates to type checkers that the method is intended to override
a method in a superclass. This allows type checkers to catch mistakes where
a method that is intended to override something in a base class
does not in fact do so.
Example::
from typing import override
class Base: def get_color(self) -> str: return "blue"
class GoodChild(Base): @override # ok: overrides Base.get_color def get_color(self) -> str: return "yellow"
class BadChild(Base): @override # type checker error: does not override Base.get_color def get_colour(self) -> str: return "red"
See :pep:698 for more details.
(Contributed by Steven Troxler in :gh:101561.)
The parser now raises :exc:SyntaxError when parsing source code containing
null bytes. (Contributed by Pablo Galindo in :gh:96670.)
A backslash-character pair that is not a valid escape sequence now generates
a :exc:SyntaxWarning, instead of :exc:DeprecationWarning.
For example, re.compile("\d+\.\d+") now emits a :exc:SyntaxWarning
("\d" is an invalid escape sequence, use raw strings for regular
expression: re.compile(r"\d+\.\d+")).
In a future Python version, :exc:SyntaxError will eventually be raised,
instead of :exc:SyntaxWarning.
(Contributed by Victor Stinner in :gh:98401.)
Octal escapes with value larger than 0o377 (ex: "\477"), deprecated
in Python 3.11, now produce a :exc:SyntaxWarning, instead of
:exc:DeprecationWarning.
In a future Python version they will be eventually a :exc:SyntaxError.
(Contributed by Victor Stinner in :gh:98401.)
Variables used in the target part of comprehensions that are not stored to
can now be used in assignment expressions (:=).
For example, in [(b := 1) for a, b.prop in some_iter], the assignment to
b is now allowed. Note that assigning to variables stored to in the target
part of comprehensions (like a) is still disallowed, as per :pep:572.
(Contributed by Nikita Sobolev in :gh:100581.)
Exceptions raised in a class or type's __set_name__ method are no longer
wrapped by a :exc:RuntimeError. Context information is added to the
exception as a :pep:678 note. (Contributed by Irit Katriel in :gh:77757.)
When a try-except* construct handles the entire :exc:ExceptionGroup
and raises one other exception, that exception is no longer wrapped in an
:exc:ExceptionGroup. Also changed in version 3.11.4. (Contributed by Irit
Katriel in :gh:103590.)
The Garbage Collector now runs only on the eval breaker mechanism of the
Python bytecode evaluation loop instead of object allocations. The GC can
also run when :c:func:PyErr_CheckSignals is called so C extensions that
need to run for a long time without executing any Python code also have a
chance to execute the GC periodically. (Contributed by Pablo Galindo in
:gh:97922.)
All builtin and extension callables expecting boolean parameters now accept
arguments of any type instead of just :class:bool and :class:int.
(Contributed by Serhiy Storchaka in :gh:60203.)
:class:memoryview now supports the half-float type (the "e" format code).
(Contributed by Donghee Na and Antoine Pitrou in :gh:90751.)
:class:slice objects are now hashable, allowing them to be used as dict keys and
set items. (Contributed by Will Bradshaw, Furkan Onder, and Raymond Hettinger in :gh:101264.)
:func:sum now uses Neumaier summation to improve accuracy and commutativity
when summing floats or mixed ints and floats.
(Contributed by Raymond Hettinger in :gh:100425.)
:func:ast.parse now raises :exc:SyntaxError instead of :exc:ValueError
when parsing source code containing null bytes. (Contributed by Pablo Galindo
in :gh:96670.)
The extraction methods in :mod:tarfile, and :func:shutil.unpack_archive,
have a new a filter argument that allows limiting tar features than may be
surprising or dangerous, such as creating files outside the destination
directory.
See :ref:tarfile extraction filters <tarfile-extraction-filter> for details.
In Python 3.14, the default will switch to 'data'.
(Contributed by Petr Viktorin in :pep:706.)
:class:types.MappingProxyType instances are now hashable if the underlying
mapping is hashable.
(Contributed by Serhiy Storchaka in :gh:87995.)
Add :ref:support for the perf profiler <perf_profiling> through the new
environment variable :envvar:PYTHONPERFSUPPORT
and command-line option :option:-X perf <-X>,
as well as the new :func:sys.activate_stack_trampoline,
:func:sys.deactivate_stack_trampoline,
and :func:sys.is_stack_trampoline_active functions.
(Design by Pablo Galindo. Contributed by Pablo Galindo and Christian Heimes
with contributions from Gregory P. Smith [Google] and Mark Shannon
in :gh:96123.)
array.array class now supports subscripting, making it a
:term:generic type. (Contributed by Jelle Zijlstra in :gh:98658.)The performance of writing to sockets in :mod:asyncio has been
significantly improved. asyncio now avoids unnecessary copying when
writing to sockets and uses :meth:~socket.socket.sendmsg if the platform
supports it. (Contributed by Kumar Aditya in :gh:91166.)
Add :func:asyncio.eager_task_factory and :func:asyncio.create_eager_task_factory
functions to allow opting an event loop in to eager task execution,
making some use-cases 2x to 5x faster.
(Contributed by Jacob Bower & Itamar Oren in :gh:102853, :gh:104140, and :gh:104138)
On Linux, :mod:asyncio uses :class:!asyncio.PidfdChildWatcher by default
if :func:os.pidfd_open is available and functional instead of
:class:!asyncio.ThreadedChildWatcher.
(Contributed by Kumar Aditya in :gh:98024.)
The event loop now uses the best available child watcher for each platform
(:class:!asyncio.PidfdChildWatcher if supported and
:class:!asyncio.ThreadedChildWatcher otherwise), so manually
configuring a child watcher is not recommended.
(Contributed by Kumar Aditya in :gh:94597.)
Add loop_factory parameter to :func:asyncio.run to allow specifying
a custom event loop factory.
(Contributed by Kumar Aditya in :gh:99388.)
Add C implementation of :func:asyncio.current_task for 4x-6x speedup.
(Contributed by Itamar Oren and Pranav Thulasiram Bhat in :gh:100344.)
:func:asyncio.iscoroutine now returns False for generators as
:mod:asyncio does not support legacy generator-based coroutines.
(Contributed by Kumar Aditya in :gh:102748.)
:func:asyncio.wait and :func:asyncio.as_completed now accepts generators
yielding tasks.
(Contributed by Kumar Aditya in :gh:78530.)
calendar.Month and :data:calendar.Day
defining months of the year and days of the week.
(Contributed by Prince Roshan in :gh:103636.)csv.QUOTE_NOTNULL and :const:csv.QUOTE_STRINGS flags to
provide finer grained control of None and empty strings by
:class:~csv.reader and :class:~csv.writer objects.Pseudo instruction opcodes (which are used by the compiler but
do not appear in executable bytecode) are now exposed in the
:mod:dis module.
:opcode:HAVE_ARGUMENT is still relevant to real opcodes,
but it is not useful for pseudo instructions. Use the new
:data:dis.hasarg collection instead.
(Contributed by Irit Katriel in :gh:94216.)
Add the :data:dis.hasexc collection to signify instructions that set
an exception handler. (Contributed by Irit Katriel in :gh:94216.)
fractions.Fraction now support float-style
formatting. (Contributed by Mark Dickinson in :gh:100161.):func:importlib.resources.as_file now supports resource directories.
(Contributed by Jason R. Coombs in :gh:97930.)
Rename first parameter of :func:importlib.resources.files to anchor.
(Contributed by Jason R. Coombs in :gh:100598.)
Add :func:inspect.markcoroutinefunction to mark sync functions that return
a :term:coroutine for use with :func:inspect.iscoroutinefunction.
(Contributed by Carlton Gibson in :gh:99247.)
Add :func:inspect.getasyncgenstate and :func:inspect.getasyncgenlocals
for determining the current state of asynchronous generators.
(Contributed by Thomas Krennwallner in :gh:79940.)
The performance of :func:inspect.getattr_static has been considerably
improved. Most calls to the function should be at least 2x faster than they
were in Python 3.11. (Contributed by Alex Waygood in :gh:103193.)
itertools.batched for collecting into even-sized
tuples where the last batch may be shorter than the rest.
(Contributed by Raymond Hettinger in :gh:98363.)Add :func:math.sumprod for computing a sum of products.
(Contributed by Raymond Hettinger in :gh:100485.)
Extend :func:math.nextafter to include a steps argument
for moving up or down multiple steps at a time. (Contributed by
Matthias Goergens, Mark Dickinson, and Raymond Hettinger in :gh:94906.)
Add :const:os.PIDFD_NONBLOCK to open a file descriptor
for a process with :func:os.pidfd_open in non-blocking mode.
(Contributed by Kumar Aditya in :gh:93312.)
:class:os.DirEntry now includes an :meth:os.DirEntry.is_junction
method to check if the entry is a junction.
(Contributed by Charles Machalow in :gh:99547.)
Add :func:os.listdrives, :func:os.listvolumes and :func:os.listmounts
functions on Windows for enumerating drives, volumes and mount points.
(Contributed by Steve Dower in :gh:102519.)
:func:os.stat and :func:os.lstat are now more accurate on Windows.
The st_birthtime field will now be filled with the creation time
of the file, and st_ctime is deprecated but still contains the
creation time (but in the future will return the last metadata change,
for consistency with other platforms). st_dev may be up to 64 bits
and st_ino up to 128 bits depending on your file system, and
st_rdev is always set to zero rather than incorrect values.
Both functions may be significantly faster on newer releases of
Windows. (Contributed by Steve Dower in :gh:99726.)
Add :func:os.path.isjunction to check if a given path is a junction.
(Contributed by Charles Machalow in :gh:99547.)
Add :func:os.path.splitroot to split a path into a triad
(drive, root, tail). (Contributed by Barney Gale in :gh:101000.)
Add support for subclassing :class:pathlib.PurePath and
:class:pathlib.Path, plus their Posix- and Windows-specific variants.
Subclasses may override the :meth:pathlib.PurePath.with_segments method
to pass information between path instances.
Add :meth:pathlib.Path.walk for walking the directory trees and generating
all file or directory names within them, similar to :func:os.walk.
(Contributed by Stanislav Zmiev in :gh:90385.)
Add walk_up optional parameter to :meth:pathlib.PurePath.relative_to
to allow the insertion of .. entries in the result; this behavior is
more consistent with :func:os.path.relpath.
(Contributed by Domenico Ragusa in :gh:84538.)
Add :meth:pathlib.Path.is_junction as a proxy to :func:os.path.isjunction.
(Contributed by Charles Machalow in :gh:99547.)
Add case_sensitive optional parameter to :meth:pathlib.Path.glob,
:meth:pathlib.Path.rglob and :meth:pathlib.PurePath.match for matching
the path's case sensitivity, allowing for more precise control over the matching process.
Windows-10.
(Contributed by Steve Dower in :gh:89545.)103693.)Add :func:random.binomialvariate.
(Contributed by Raymond Hettinger in :gh:81620.)
Add a default of lambd=1.0 to :func:random.expovariate.
(Contributed by Raymond Hettinger in :gh:100234.)
:func:shutil.make_archive now passes the root_dir argument to custom
archivers which support it.
In this case it no longer temporarily changes the current working directory
of the process to root_dir to perform archiving.
(Contributed by Serhiy Storchaka in :gh:74696.)
:func:shutil.rmtree now accepts a new argument onexc which is an
error handler like onerror but which expects an exception instance
rather than a (typ, val, tb) triplet. onerror is deprecated.
(Contributed by Irit Katriel in :gh:102828.)
:func:shutil.which now consults the PATHEXT environment variable to
find matches within PATH on Windows even when the given cmd includes
a directory component.
(Contributed by Charles Machalow in :gh:103179.)
:func:shutil.which will call NeedCurrentDirectoryForExePathW when
querying for executables on Windows to determine if the current working
directory should be prepended to the search path.
(Contributed by Charles Machalow in :gh:103179.)
:func:shutil.which will return a path matching the cmd with a component
from PATHEXT prior to a direct match elsewhere in the search path on
Windows.
(Contributed by Charles Machalow in :gh:103179.)
Add a :ref:command-line interface <sqlite3-cli>.
(Contributed by Erlend E. Aasland in :gh:77617.)
Add the :attr:sqlite3.Connection.autocommit attribute
to :class:sqlite3.Connection
and the autocommit parameter to :func:sqlite3.connect
to control :pep:249-compliant
:ref:transaction handling <sqlite3-transaction-control-autocommit>.
(Contributed by Erlend E. Aasland in :gh:83638.)
Add entrypoint keyword-only parameter to
:meth:sqlite3.Connection.load_extension,
for overriding the SQLite extension entry point.
(Contributed by Erlend E. Aasland in :gh:103015.)
Add :meth:sqlite3.Connection.getconfig and
:meth:sqlite3.Connection.setconfig to :class:sqlite3.Connection
to make configuration changes to a database connection.
(Contributed by Erlend E. Aasland in :gh:103489.)
statistics.correlation to include as a ranked method
for computing the Spearman correlation of ranked data.
(Contributed by Raymond Hettinger in :gh:95861.)Add the :mod:sys.monitoring namespace to expose the new :ref:PEP 669 <whatsnew312-pep669> monitoring API.
(Contributed by Mark Shannon in :gh:103082.)
Add :func:sys.activate_stack_trampoline and
:func:sys.deactivate_stack_trampoline for activating and deactivating
stack profiler trampolines,
and :func:sys.is_stack_trampoline_active for querying if stack profiler
trampolines are active.
(Contributed by Pablo Galindo and Christian Heimes
with contributions from Gregory P. Smith [Google] and Mark Shannon
in :gh:96123.)
Add :data:sys.last_exc which holds the last unhandled exception that
was raised (for post-mortem debugging use cases). Deprecate the
three fields that have the same information in its legacy form:
:data:sys.last_type, :data:sys.last_value and :data:sys.last_traceback.
(Contributed by Irit Katriel in :gh:102778.)
:func:sys._current_exceptions now returns a mapping from thread-id to an
exception instance, rather than to a (typ, exc, tb) tuple.
(Contributed by Irit Katriel in :gh:103176.)
:func:sys.setrecursionlimit and :func:sys.getrecursionlimit.
The recursion limit now applies only to Python code. Builtin functions do
not use the recursion limit, but are protected by a different mechanism
that prevents recursion from causing a virtual machine crash.
tempfile.NamedTemporaryFile function has a new optional parameter
delete_on_close (Contributed by Evgeny Zorin in :gh:58451.)tempfile.mkdtemp now always returns an absolute path, even if the
argument provided to the dir parameter is a relative path.threading.settrace_all_threads and
:func:threading.setprofile_all_threads that allow to set tracing and
profiling functions in all running threads in addition to the calling one.
(Contributed by Pablo Galindo in :gh:93503.)tkinter.Canvas.coords() now flattens its arguments.
It now accepts not only coordinates as separate arguments
(x1, y1, x2, y2, ...) and a sequence of coordinates
([x1, y1, x2, y2, ...]), but also coordinates grouped in pairs
((x1, y1), (x2, y2), ... and [(x1, y1), (x2, y2), ...]),
like create_*() methods.
(Contributed by Serhiy Storchaka in :gh:94473.)tokenize module includes the changes introduced in :pep:701.
(Contributed by Marta Gómez Macías and Pablo Galindo in :gh:102856.)
See :ref:whatsnew312-porting-to-python312 for more information on the
changes to the :mod:tokenize module.types.get_original_bases to allow for further introspection of
:ref:user-defined-generics when subclassed. (Contributed by
James Hilton-Balfe and Alex Waygood in :gh:101827.).. _whatsnew-typing-py312:
:func:isinstance checks against
:func:runtime-checkable protocols <typing.runtime_checkable> now use
:func:inspect.getattr_static rather than :func:hasattr to lookup whether
attributes exist. This means that descriptors and :meth:~object.__getattr__
methods are no longer unexpectedly evaluated during isinstance() checks
against runtime-checkable protocols. However, it may also mean that some
objects which used to be considered instances of a runtime-checkable protocol
may no longer be considered instances of that protocol on Python 3.12+, and
vice versa. Most users are unlikely to be affected by this change.
(Contributed by Alex Waygood in :gh:102433.)
The members of a runtime-checkable protocol are now considered "frozen" at
runtime as soon as the class has been created. Monkey-patching attributes
onto a runtime-checkable protocol will still work, but will have no impact on
:func:isinstance checks comparing objects to the protocol. For example::
>>> from typing import Protocol, runtime_checkable
>>> @runtime_checkable
... class HasX(Protocol):
... x = 1
...
>>> class Foo: ...
...
>>> f = Foo()
>>> isinstance(f, HasX)
False
>>> f.x = 1
>>> isinstance(f, HasX)
True
>>> HasX.y = 2
>>> isinstance(f, HasX) # unchanged, even though HasX now also has a "y" attribute
True
This change was made in order to speed up isinstance() checks against
runtime-checkable protocols.
The performance profile of :func:isinstance checks against
:func:runtime-checkable protocols <typing.runtime_checkable> has changed
significantly. Most isinstance() checks against protocols with only a few
members should be at least 2x faster than in 3.11, and some may be 20x
faster or more. However, isinstance() checks against protocols with many
members may be slower than in Python 3.11. (Contributed by Alex
Waygood in :gh:74690 and :gh:103193.)
All :data:typing.TypedDict and :data:typing.NamedTuple classes now have the
__orig_bases__ attribute. (Contributed by Adrian Garcia Badaracco in
:gh:103699.)
Add frozen_default parameter to :func:typing.dataclass_transform.
(Contributed by Erik De Bonte in :gh:99957.)
96734).Add a --durations command line option, showing the N slowest test cases::
1.210s test_timeout (Lib.test.test_threading.BarrierTests) 1.003s test_default_timeout (Lib.test.test_threading.BarrierTests) 0.518s test_timeout (Lib.test.test_threading.EventTests)
Ran 158 tests in 9.869s
OK (skipped=3)
(Contributed by Giampaolo Rodola in :gh:48330)
command-line interface <uuid-cli>.
(Contributed by Adam Chhina in :gh:88597.)Remove wstr and wstr_length members from Unicode objects.
It reduces object size by 8 or 16 bytes on 64bit platform. (:pep:623)
(Contributed by Inada Naoki in :gh:92536.)
Add experimental support for using the BOLT binary optimizer in the build
process, which improves performance by 1-5%.
(Contributed by Kevin Modzelewski in :gh:90536 and tuned by Donghee Na in :gh:101525)
Speed up the regular expression substitution (functions :func:re.sub and
:func:re.subn and corresponding :class:!re.Pattern methods) for
replacement strings containing group references by 2--3 times.
(Contributed by Serhiy Storchaka in :gh:91524.)
Speed up :class:asyncio.Task creation by deferring expensive string formatting.
(Contributed by Itamar Oren in :gh:103793.)
The :func:tokenize.tokenize and :func:tokenize.generate_tokens functions are
up to 64% faster as a side effect of the changes required to cover :pep:701 in
the :mod:tokenize module. (Contributed by Marta Gómez Macías and Pablo Galindo
in :gh:102856.)
Speed up :func:super method calls and attribute loads via the
new :opcode:LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and
Vladimir Matveev in :gh:103497.)
Remove the :opcode:!LOAD_METHOD instruction. It has been merged into
:opcode:LOAD_ATTR. :opcode:LOAD_ATTR will now behave like the old
:opcode:!LOAD_METHOD instruction if the low bit of its oparg is set.
(Contributed by Ken Jin in :gh:93429.)
Remove the :opcode:!JUMP_IF_FALSE_OR_POP and :opcode:!JUMP_IF_TRUE_OR_POP
instructions. (Contributed by Irit Katriel in :gh:102859.)
Remove the :opcode:!PRECALL instruction. (Contributed by Mark Shannon in
:gh:92925.)
Add the :opcode:BINARY_SLICE and :opcode:STORE_SLICE instructions.
(Contributed by Mark Shannon in :gh:94163.)
Add the :opcode:CALL_INTRINSIC_1 instructions.
(Contributed by Mark Shannon in :gh:99005.)
Add the :opcode:CALL_INTRINSIC_2 instruction.
(Contributed by Irit Katriel in :gh:101799.)
Add the :opcode:CLEANUP_THROW instruction.
(Contributed by Brandt Bucher in :gh:90997.)
Add the :opcode:!END_SEND instruction.
(Contributed by Mark Shannon in :gh:103082.)
Add the :opcode:LOAD_FAST_AND_CLEAR instruction as part of the
implementation of :pep:709. (Contributed by Carl Meyer in :gh:101441.)
Add the :opcode:LOAD_FAST_CHECK instruction.
(Contributed by Dennis Sweeney in :gh:93143.)
Add the :opcode:LOAD_FROM_DICT_OR_DEREF, :opcode:LOAD_FROM_DICT_OR_GLOBALS,
and :opcode:LOAD_LOCALS opcodes as part of the implementation of :pep:695.
Remove the :opcode:!LOAD_CLASSDEREF opcode, which can be replaced with
:opcode:LOAD_LOCALS plus :opcode:LOAD_FROM_DICT_OR_DEREF. (Contributed
by Jelle Zijlstra in :gh:103764.)
Add the :opcode:LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and
Vladimir Matveev in :gh:103497.)
Add the RETURN_CONST instruction. (Contributed by Wenyang Wang in :gh:101632.)
Remove the Tools/demo/ directory which contained old demo scripts. A copy
can be found in the old-demos project <https://github.com/gvanrossum/old-demos>_.
(Contributed by Victor Stinner in :gh:97681.)
Remove outdated example scripts of the Tools/scripts/ directory.
A copy can be found in the old-demos project <https://github.com/gvanrossum/old-demos>_.
(Contributed by Victor Stinner in :gh:97669.)
:mod:argparse: The type, choices, and metavar parameters
of :class:!argparse.BooleanOptionalAction are deprecated
and will be removed in 3.14.
(Contributed by Nikita Sobolev in :gh:92248.)
:mod:ast: The following :mod:ast features have been deprecated in documentation since
Python 3.8, now cause a :exc:DeprecationWarning to be emitted at runtime
when they are accessed or used, and will be removed in Python 3.14:
!ast.Num!ast.Str!ast.Bytes!ast.NameConstant!ast.EllipsisUse :class:ast.Constant instead.
(Contributed by Serhiy Storchaka in :gh:90953.)
:mod:asyncio:
The child watcher classes :class:!asyncio.MultiLoopChildWatcher,
:class:!asyncio.FastChildWatcher, :class:!asyncio.AbstractChildWatcher
and :class:!asyncio.SafeChildWatcher are deprecated and
will be removed in Python 3.14.
(Contributed by Kumar Aditya in :gh:94597.)
:func:!asyncio.set_child_watcher, :func:!asyncio.get_child_watcher,
:meth:!asyncio.AbstractEventLoopPolicy.set_child_watcher and
:meth:!asyncio.AbstractEventLoopPolicy.get_child_watcher are deprecated
and will be removed in Python 3.14.
(Contributed by Kumar Aditya in :gh:94597.)
The :meth:~asyncio.get_event_loop method of the
default event loop policy now emits a :exc:DeprecationWarning if there
is no current event loop set and it decides to create one.
(Contributed by Serhiy Storchaka and Guido van Rossum in :gh:100160.)
:mod:calendar: calendar.January and calendar.February constants are deprecated and
replaced by :data:calendar.JANUARY and :data:calendar.FEBRUARY.
(Contributed by Prince Roshan in :gh:103636.)
:mod:collections.abc: Deprecated :class:collections.abc.ByteString.
Use isinstance(obj, collections.abc.Buffer) to test if obj implements
the :ref:buffer protocol <bufferobjects> at runtime. For use in type
annotations, either use :class:~collections.abc.Buffer or a union
that explicitly specifies the types your code supports (e.g.,
bytes | bytearray | memoryview).
:class:!ByteString was originally intended to be an abstract class that
would serve as a supertype of both :class:bytes and :class:bytearray.
However, since the ABC never had any methods, knowing that an object was an
instance of :class:!ByteString never actually told you anything useful
about the object. Other common buffer types such as :class:memoryview were
also never understood as subtypes of :class:!ByteString (either at
runtime or by static type checkers).
See :pep:PEP 688 <688#current-options> for more details.
(Contributed by Shantanu Jain in :gh:91896.)
:mod:datetime: :class:datetime.datetime's :meth:~datetime.datetime.utcnow and
:meth:~datetime.datetime.utcfromtimestamp are deprecated and will be
removed in a future version. Instead, use timezone-aware objects to represent
datetimes in UTC: respectively, call :meth:~datetime.datetime.now and
:meth:~datetime.datetime.fromtimestamp with the tz parameter set to
:const:datetime.UTC.
(Contributed by Paul Ganssle in :gh:103857.)
:mod:email: Deprecate the isdst parameter in :func:email.utils.localtime.
(Contributed by Alan Williams in :gh:72346.)
:mod:importlib.abc: Deprecated the following classes, scheduled for removal in
Python 3.14:
!importlib.abc.ResourceReader!importlib.abc.Traversable!importlib.abc.TraversableResourcesUse :mod:importlib.resources.abc classes instead:
importlib.resources.abc.Traversableimportlib.resources.abc.TraversableResources(Contributed by Jason R. Coombs and Hugo van Kemenade in :gh:93963.)
:mod:itertools: Deprecate the support for copy, deepcopy, and pickle operations,
which is undocumented, inefficient, historically buggy, and inconsistent.
This will be removed in 3.14 for a significant reduction in code
volume and maintenance burden.
(Contributed by Raymond Hettinger in :gh:101588.)
:mod:multiprocessing: In Python 3.14, the default :mod:multiprocessing
start method will change to a safer one on Linux, BSDs,
and other non-macOS POSIX platforms where 'fork' is currently
the default (:gh:84559). Adding a runtime warning about this was deemed too
disruptive as the majority of code is not expected to care. Use the
:func:~multiprocessing.get_context or
:func:~multiprocessing.set_start_method APIs to explicitly specify when
your code requires 'fork'. See :ref:contexts and start methods <multiprocessing-start-methods>.
:mod:pkgutil: :func:!pkgutil.find_loader and :func:!pkgutil.get_loader
are deprecated and will be removed in Python 3.14;
use :func:importlib.util.find_spec instead.
(Contributed by Nikita Sobolev in :gh:97850.)
:mod:pty: The module has two undocumented master_open() and slave_open()
functions that have been deprecated since Python 2 but only gained a
proper :exc:DeprecationWarning in 3.12. Remove them in 3.14.
(Contributed by Soumendra Ganguly and Gregory P. Smith in :gh:85984.)
:mod:os:
The st_ctime fields return by :func:os.stat and :func:os.lstat on
Windows are deprecated. In a future release, they will contain the last
metadata change time, consistent with other platforms. For now, they still
contain the creation time, which is also available in the new st_birthtime
field. (Contributed by Steve Dower in :gh:99726.)
On POSIX platforms, :func:os.fork can now raise a
:exc:DeprecationWarning when it can detect being called from a
multithreaded process. There has always been a fundamental incompatibility
with the POSIX platform when doing so. Even if such code appeared to work.
We added the warning to raise awareness as issues encountered by code doing
this are becoming more frequent. See the :func:os.fork documentation for
more details along with this discussion on fork being incompatible with threads <https://discuss.python.org/t/concerns-regarding-deprecation-of-fork-with-alive-threads/33555>_ for why we're now surfacing this
longstanding platform compatibility problem to developers.
When this warning appears due to usage of :mod:multiprocessing or
:mod:concurrent.futures the fix is to use a different
:mod:multiprocessing start method such as "spawn" or "forkserver".
:mod:shutil: The onerror argument of :func:shutil.rmtree is deprecated;
use onexc instead. (Contributed by Irit Katriel in :gh:102828.)
:mod:sqlite3:
:ref:default adapters and converters <sqlite3-default-converters> are now deprecated.
Instead, use the :ref:sqlite3-adapter-converter-recipes
and tailor them to your needs.
(Contributed by Erlend E. Aasland in :gh:90016.)
In :meth:~sqlite3.Cursor.execute, :exc:DeprecationWarning is now emitted
when :ref:named placeholders <sqlite3-placeholders> are used together with
parameters supplied as a :term:sequence instead of as a :class:dict.
Starting from Python 3.14, using named placeholders with parameters supplied
as a sequence will raise a :exc:~sqlite3.ProgrammingError.
(Contributed by Erlend E. Aasland in :gh:101698.)
:mod:sys: The :data:sys.last_type, :data:sys.last_value and :data:sys.last_traceback
fields are deprecated. Use :data:sys.last_exc instead.
(Contributed by Irit Katriel in :gh:102778.)
:mod:tarfile: Extracting tar archives without specifying filter is deprecated until
Python 3.14, when 'data' filter will become the default.
See :ref:tarfile-extraction-filter for details.
:mod:typing:
:class:typing.Hashable and :class:typing.Sized, aliases for
:class:collections.abc.Hashable and :class:collections.abc.Sized respectively, are
deprecated. (:gh:94309.)
:class:typing.ByteString, deprecated since Python 3.9, now causes a
:exc:DeprecationWarning to be emitted when it is used.
(Contributed by Alex Waygood in :gh:91896.)
:mod:xml.etree.ElementTree: The module now emits :exc:DeprecationWarning
when testing the truth value of an :class:xml.etree.ElementTree.Element.
Before, the Python implementation emitted :exc:FutureWarning, and the C
implementation emitted nothing.
(Contributed by Jacob Walls in :gh:83122.)
The 3-arg signatures (type, value, traceback) of :meth:coroutine throw() <coroutine.throw>, :meth:generator throw() <generator.throw> and
:meth:async generator throw() <agen.athrow> are deprecated and
may be removed in a future version of Python. Use the single-arg versions
of these functions instead. (Contributed by Ofey Chan in :gh:89874.)
:exc:DeprecationWarning is now raised when :attr:~module.__package__ on a
module differs from
:attr:__spec__.parent <importlib.machinery.ModuleSpec.parent> (previously
it was :exc:ImportWarning).
(Contributed by Brett Cannon in :gh:65961.)
Setting :attr:~module.__package__ or __cached__ on a
module is deprecated, and will cease to be set or taken into consideration by
the import system in Python 3.14. (Contributed by Brett Cannon in :gh:65961.)
The bitwise inversion operator (~) on bool is deprecated. It will throw an
error in Python 3.16. Use not for logical negation of bools instead.
In the rare case that you really need the bitwise inversion of the underlying
int, convert to int explicitly: ~int(x). (Contributed by Tim Hoffmann
in :gh:103487.)
Accessing :attr:~codeobject.co_lnotab on code objects was deprecated in
Python 3.10 via :pep:626,
but it only got a proper :exc:DeprecationWarning in 3.12.
May be removed in 3.15.
(Contributed by Nikita Sobolev in :gh:101866.)
.. include:: ../deprecations/pending-removal-in-3.13.rst
.. include:: ../deprecations/pending-removal-in-3.14.rst
.. include:: ../deprecations/pending-removal-in-3.15.rst
.. include:: ../deprecations/pending-removal-in-3.16.rst
.. include:: ../deprecations/pending-removal-in-3.17.rst
.. include:: ../deprecations/pending-removal-in-3.19.rst
.. include:: ../deprecations/pending-removal-in-3.20.rst
.. include:: ../deprecations/pending-removal-in-future.rst
.. _whatsnew312-removed:
594,
having been deprecated in Python 3.6.
Use :mod:asyncio instead.
(Contributed by Nikita Sobolev in :gh:96580.)Several names deprecated in the :mod:configparser way back in 3.2 have
been removed per :gh:89336:
configparser.ParsingError no longer has a filename attribute
or argument. Use the source attribute and argument instead.configparser no longer has a SafeConfigParser class. Use the
shorter :class:~configparser.ConfigParser name instead.configparser.ConfigParser no longer has a readfp method.
Use :meth:~configparser.ConfigParser.read_file instead... _whatsnew312-removed-distutils:
!distutils package. It was deprecated in Python 3.10 by
:pep:632 "Deprecate distutils module". For projects still using
distutils and cannot be updated to something else, the setuptools
project can be installed: it still provides distutils.
(Contributed by Victor Stinner in :gh:92584.)Remove the bundled setuptools wheel from :mod:ensurepip,
and stop installing setuptools in environments created by :mod:venv.
pip (>= 22.1) does not require setuptools to be installed in the
environment. setuptools-based (and distutils-based) packages
can still be used with pip install, since pip will provide
setuptools in the build environment it uses for building a
package.
easy_install, pkg_resources, setuptools and distutils
are no longer provided by default in environments created with
venv or bootstrapped with ensurepip, since they are part of
the setuptools package. For projects relying on these at runtime,
the setuptools project should be declared as a dependency and
installed separately (typically, using pip).
(Contributed by Pradyun Gedam in :gh:95299.)
enum's EnumMeta.__getattr__, which is no longer needed for
enum attribute access.
(Contributed by Ethan Furman in :gh:95083.)ftplib's FTP_TLS.ssl_version class attribute: use the
context parameter instead.
(Contributed by Victor Stinner in :gh:94172.)filename attribute of :mod:gzip's :class:gzip.GzipFile,
deprecated since Python 2.6, use the :attr:~gzip.GzipFile.name attribute
instead. In write mode, the filename attribute added '.gz' file
extension if it was not present.
(Contributed by Victor Stinner in :gh:94196.)hashlib's
:func:hashlib.pbkdf2_hmac, deprecated in Python 3.10. Python 3.10 and
newer requires OpenSSL 1.1.1 (:pep:644): this OpenSSL version provides
a C implementation of :func:~hashlib.pbkdf2_hmac which is faster.
(Contributed by Victor Stinner in :gh:94199.)Many previously deprecated cleanups in :mod:importlib have now been
completed:
References to, and support for :meth:!module_repr has been removed.
(Contributed by Barry Warsaw in :gh:97850.)
importlib.util.set_package, importlib.util.set_loader and
importlib.util.module_for_loader have all been removed. (Contributed by
Brett Cannon and Nikita Sobolev in :gh:65961 and :gh:97850.)
Support for find_loader() and find_module() APIs have been
removed. (Contributed by Barry Warsaw in :gh:98040.)
importlib.abc.Finder, pkgutil.ImpImporter, and pkgutil.ImpLoader
have been removed. (Contributed by Barry Warsaw in :gh:98040.)
.. _whatsnew312-removed-imp:
The :mod:!imp module has been removed. (Contributed by Barry Warsaw in
:gh:98040.)
To migrate, consult the following correspondence table:
================================= =======================================
imp importlib
================================= =======================================
imp.NullImporter Insert None into sys.path_importer_cache
imp.cache_from_source() :func:importlib.util.cache_from_source
imp.find_module() :func:importlib.util.find_spec
imp.get_magic() :const:importlib.util.MAGIC_NUMBER
imp.get_suffixes() :const:importlib.machinery.SOURCE_SUFFIXES, :const:importlib.machinery.EXTENSION_SUFFIXES, and :const:importlib.machinery.BYTECODE_SUFFIXES
imp.get_tag() :attr:sys.implementation.cache_tag <sys.implementation>
imp.load_module() :func:importlib.import_module
imp.new_module(name) types.ModuleType(name)
imp.reload() :func:importlib.reload
imp.source_from_cache() :func:importlib.util.source_from_cache
imp.load_source() See below
================================= =======================================
Replace imp.load_source() with::
import importlib.util
import importlib.machinery
def load_source(modname, filename):
loader = importlib.machinery.SourceFileLoader(modname, filename)
spec = importlib.util.spec_from_file_location(modname, filename, loader=loader)
module = importlib.util.module_from_spec(spec)
# The module is always executed and not cached in sys.modules.
# Uncomment the following line to cache the module.
# sys.modules[module.__name__] = module
loader.exec_module(module)
return module
Remove :mod:!imp functions and attributes with no replacements:
Undocumented functions:
imp.init_builtin()imp.load_compiled()imp.load_dynamic()imp.load_package()imp.lock_held(), imp.acquire_lock(), imp.release_lock():
the locking scheme has changed in Python 3.3 to per-module locks.
imp.find_module() constants: SEARCH_ERROR, PY_SOURCE,
PY_COMPILED, C_EXTENSION, PY_RESOURCE, PKG_DIRECTORY,
C_BUILTIN, PY_FROZEN, PY_CODERESOURCE, IMP_HOOK.
io's io.OpenWrapper and _pyio.OpenWrapper, deprecated in Python
3.10: just use :func:open instead. The :func:open (:func:io.open)
function is a built-in function. Since Python 3.10, :func:!_pyio.open is
also a static method.
(Contributed by Victor Stinner in :gh:94169.)locale's :func:!locale.format function, deprecated in Python 3.7:
use :func:locale.format_string instead.
(Contributed by Victor Stinner in :gh:94226.)smtpd module has been removed according to the schedule in :pep:594,
having been deprecated in Python 3.4.7 and 3.5.4.
Use the :pypi:aiosmtpd PyPI module or any other
:mod:asyncio-based server instead.
(Contributed by Oleg Iarygin in :gh:93243.)The following undocumented :mod:sqlite3 features, deprecated in Python
3.10, are now removed:
sqlite3.enable_shared_cache()sqlite3.OptimizedUnicodeIf a shared cache must be used, open the database in URI mode using the
cache=shared query parameter.
The sqlite3.OptimizedUnicode text factory has been an alias for
:class:str since Python 3.3. Code that previously set the text factory to
OptimizedUnicode can either use str explicitly, or rely on the
default value which is also str.
(Contributed by Erlend E. Aasland in :gh:92548.)
Remove :mod:ssl's :func:!ssl.RAND_pseudo_bytes function, deprecated in Python 3.6:
use :func:os.urandom or :func:ssl.RAND_bytes instead.
(Contributed by Victor Stinner in :gh:94199.)
Remove the :func:!ssl.match_hostname function.
It was deprecated in Python 3.7. OpenSSL performs
hostname matching since Python 3.7, Python no longer uses the
:func:!ssl.match_hostname function.
(Contributed by Victor Stinner in :gh:94199.)
Remove the :func:!ssl.wrap_socket function, deprecated in Python 3.7:
instead, create a :class:ssl.SSLContext object and call its
:class:ssl.SSLContext.wrap_socket method. Any package that still uses
:func:!ssl.wrap_socket is broken and insecure. The function neither sends a
SNI TLS extension nor validates the server hostname. Code is subject to :cwe:295
(Improper Certificate Validation).
(Contributed by Victor Stinner in :gh:94199.)
Remove many long-deprecated :mod:unittest features:
.. _unittest-TestCase-removed-aliases:
A number of :class:~unittest.TestCase method aliases:
============================ =============================== ===============
Deprecated alias Method Name Deprecated in
============================ =============================== ===============
failUnless :meth:.assertTrue 3.1
failIf :meth:.assertFalse 3.1
failUnlessEqual :meth:.assertEqual 3.1
failIfEqual :meth:.assertNotEqual 3.1
failUnlessAlmostEqual :meth:.assertAlmostEqual 3.1
failIfAlmostEqual :meth:.assertNotAlmostEqual 3.1
failUnlessRaises :meth:.assertRaises 3.1
assert_ :meth:.assertTrue 3.2
assertEquals :meth:.assertEqual 3.2
assertNotEquals :meth:.assertNotEqual 3.2
assertAlmostEquals :meth:.assertAlmostEqual 3.2
assertNotAlmostEquals :meth:.assertNotAlmostEqual 3.2
assertRegexpMatches :meth:.assertRegex 3.2
assertRaisesRegexp :meth:.assertRaisesRegex 3.2
assertNotRegexpMatches :meth:.assertNotRegex 3.5
============================ =============================== ===============
You can use https://github.com/isidentical/teyit to automatically modernise your unit tests.
Undocumented and broken :class:~unittest.TestCase method
assertDictContainsSubset (deprecated in Python 3.2).
Undocumented :meth:TestLoader.loadTestsFromModule <unittest.TestLoader.loadTestsFromModule> parameter use_load_tests
(deprecated and ignored since Python 3.5).
An alias of the :class:~unittest.TextTestResult class:
_TextTestResult (deprecated in Python 3.2).
(Contributed by Serhiy Storchaka in :gh:89325.)
webbrowser.
The removed browsers include: Grail, Mosaic, Netscape, Galeon, Skipstone,
Iceape, Firebird, and Firefox versions 35 and below (:gh:102871).ElementTree.Element.copy() method of the
pure Python implementation, deprecated in Python 3.10, use the
:func:copy.copy function instead. The C implementation of :mod:xml.etree.ElementTree
has no copy() method, only a __copy__() method.
(Contributed by Victor Stinner in :gh:94383.)zipimport's find_loader() and find_module() methods,
deprecated in Python 3.10: use the find_spec() method instead. See
:pep:451 for the rationale.
(Contributed by Victor Stinner in :gh:94379.)Remove the suspicious rule from the documentation :file:Makefile and
:file:Doc/tools/rstlint.py, both in favor of sphinx-lint <https://github.com/sphinx-contrib/sphinx-lint>_.
(Contributed by Julien Palard in :gh:98179.)
Remove the keyfile and certfile parameters from the
:mod:ftplib, :mod:imaplib, :mod:poplib and :mod:smtplib modules,
and the key_file, cert_file and check_hostname parameters from the
:mod:http.client module,
all deprecated since Python 3.6. Use the context parameter
(ssl_context in :mod:imaplib) instead.
(Contributed by Victor Stinner in :gh:94172.)
Remove Jython compatibility hacks from several stdlib modules and tests.
(Contributed by Nikita Sobolev in :gh:99482.)
Remove _use_broken_old_ctypes_structure_semantics_ flag
from :mod:ctypes module.
(Contributed by Nikita Sobolev in :gh:99285.)
.. _whatsnew312-porting-to-python312:
This section lists previously described changes and other bugfixes that may require changes to your code.
More strict rules are now applied for numerical group references and
group names in regular expressions.
Only sequence of ASCII digits is now accepted as a numerical reference.
The group name in bytes patterns and replacement strings can now only
contain ASCII letters and digits and underscore.
(Contributed by Serhiy Storchaka in :gh:91760.)
Remove randrange() functionality deprecated since Python 3.10. Formerly,
randrange(10.0) losslessly converted to randrange(10). Now, it raises a
:exc:TypeError. Also, the exception raised for non-integer values such as
randrange(10.5) or randrange('10') has been changed from :exc:ValueError to
:exc:TypeError. This also prevents bugs where randrange(1e25) would silently
select from a larger range than randrange(10**25).
(Originally suggested by Serhiy Storchaka :gh:86388.)
:class:argparse.ArgumentParser changed encoding and error handler
for reading arguments from file (e.g. fromfile_prefix_chars option)
from default text encoding (e.g. :func:locale.getpreferredencoding(False) <locale.getpreferredencoding>)
to :term:filesystem encoding and error handler.
Argument files should be encoded in UTF-8 instead of ANSI Codepage on Windows.
Remove the asyncore-based smtpd module deprecated in Python 3.4.7
and 3.5.4. A recommended replacement is the
:mod:asyncio-based :pypi:aiosmtpd PyPI module.
:func:shlex.split: Passing None for s argument now raises an
exception, rather than reading :data:sys.stdin. The feature was deprecated
in Python 3.9.
(Contributed by Victor Stinner in :gh:94352.)
The :mod:os module no longer accepts bytes-like paths, like
:class:bytearray and :class:memoryview types: only the exact
:class:bytes type is accepted for bytes strings.
(Contributed by Victor Stinner in :gh:98393.)
:func:syslog.openlog and :func:syslog.closelog now fail if used in subinterpreters.
:func:syslog.syslog may still be used in subinterpreters,
but now only if :func:syslog.openlog has already been called in the main interpreter.
These new restrictions do not apply to the main interpreter,
so only a very small set of users might be affected.
This change helps with interpreter isolation. Furthermore, :mod:syslog is a wrapper
around process-global resources, which are best managed from the main interpreter.
(Contributed by Donghee Na in :gh:99127.)
The undocumented locking behavior of :func:~functools.cached_property
is removed, because it locked across all instances of the class, leading to high
lock contention. This means that a cached property getter function could now run
more than once for a single instance, if two threads race. For most simple
cached properties (e.g. those that are idempotent and simply calculate a value
based on other attributes of the instance) this will be fine. If
synchronization is needed, implement locking within the cached property getter
function or around multi-threaded access points.
:func:sys._current_exceptions now returns a mapping from thread-id to an
exception instance, rather than to a (typ, exc, tb) tuple.
(Contributed by Irit Katriel in :gh:103176.)
When extracting tar files using :mod:tarfile or
:func:shutil.unpack_archive, pass the filter argument to limit features
that may be surprising or dangerous.
See :ref:tarfile-extraction-filter for details.
The output of the :func:tokenize.tokenize and :func:tokenize.generate_tokens
functions is now changed due to the changes introduced in :pep:701. This
means that STRING tokens are not emitted any more for f-strings and the
tokens described in :pep:701 are now produced instead: FSTRING_START,
FSTRING_MIDDLE and FSTRING_END are now emitted for f-string "string"
parts in addition to the appropriate tokens for the tokenization in the
expression components. For example for the f-string f"start {1+1} end"
the old version of the tokenizer emitted::
1,0-1,18: STRING 'f"start {1+1} end"'
while the new version emits::
1,0-1,2: FSTRING_START 'f"'
1,2-1,8: FSTRING_MIDDLE 'start '
1,8-1,9: OP '{'
1,9-1,10: NUMBER '1'
1,10-1,11: OP '+'
1,11-1,12: NUMBER '1'
1,12-1,13: OP '}'
1,13-1,17: FSTRING_MIDDLE ' end'
1,17-1,18: FSTRING_END '"'
Additionally, there may be some minor behavioral changes as a consequence of the
changes required to support :pep:701. Some of these changes include:
The type attribute of the tokens emitted when tokenizing some invalid Python
characters such as ! has changed from ERRORTOKEN to OP.
Incomplete single-line strings now also raise :exc:tokenize.TokenError as incomplete
multiline strings do.
Some incomplete or invalid Python code now raises :exc:tokenize.TokenError instead of
returning arbitrary ERRORTOKEN tokens when tokenizing it.
Mixing tabs and spaces as indentation in the same file is not supported anymore and will
raise a :exc:TabError.
The :mod:threading module now expects the :mod:!_thread module to have
an _is_main_interpreter attribute. It is a function with no
arguments that returns True if the current interpreter is the
main interpreter.
Any library or application that provides a custom _thread module
should provide _is_main_interpreter().
(See :gh:112826.)
Python no longer uses :file:setup.py to build shared C extension modules.
Build parameters like headers and libraries are detected in configure
script. Extensions are built by :file:Makefile. Most extensions use
pkg-config and fall back to manual detection.
(Contributed by Christian Heimes in :gh:93939.)
va_start() with two parameters, like va_start(args, format),
is now required to build Python.
va_start() is no longer called with a single parameter.
(Contributed by Kumar Aditya in :gh:93207.)
CPython now uses the ThinLTO option as the default link time optimization policy
if the Clang compiler accepts the flag.
(Contributed by Donghee Na in :gh:89536.)
Add COMPILEALL_OPTS variable in :file:Makefile to override :mod:compileall
options (default: -j0) in make install. Also merged the 3
compileall commands into a single command to build .pyc files for all
optimization levels (0, 1, 2) at once.
(Contributed by Victor Stinner in :gh:99289.)
Add platform triplets for 64-bit LoongArch:
(Contributed by Zhang Na in :gh:90656.)
PYTHON_FOR_REGEN now require Python 3.10 or newer.
Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate
:file:configure.
(Contributed by Christian Heimes in :gh:89886.)
Windows builds and macOS installers from python.org now use OpenSSL 3.0.
.. _whatsnew312-pep697:
:pep:697: Introduce the :ref:Unstable C API tier <unstable-c-api>,
intended for low-level tools like debuggers and JIT compilers.
This API may change in each minor release of CPython without deprecation
warnings.
Its contents are marked by the PyUnstable_ prefix in names.
Code object constructors:
PyUnstable_Code_New() (renamed from PyCode_New)PyUnstable_Code_NewWithPosOnlyArgs() (renamed from PyCode_NewWithPosOnlyArgs)Extra storage for code objects (:pep:523):
PyUnstable_Eval_RequestCodeExtraIndex() (renamed from _PyEval_RequestCodeExtraIndex)PyUnstable_Code_GetExtra() (renamed from _PyCode_GetExtra)PyUnstable_Code_SetExtra() (renamed from _PyCode_SetExtra)The original names will continue to be available until the respective API changes.
(Contributed by Petr Viktorin in :gh:101101.)
:pep:697: Add an API for extending types whose instance memory layout is
opaque:
PyType_Spec.basicsize can be zero or negative to specify
inheriting or extending the base class size.PyObject_GetTypeData and :c:func:PyType_GetTypeDataSize
added to allow access to subclass-specific instance data.Py_TPFLAGS_ITEMS_AT_END and :c:func:PyObject_GetItemData
added to allow safely extending certain variable-sized types, including
:c:var:PyType_Type.Py_RELATIVE_OFFSET added to allow defining
:c:type:members <PyMemberDef> in terms of a subclass-specific struct.(Contributed by Petr Viktorin in :gh:103509.)
Add the new :ref:limited C API <limited-c-api> function :c:func:PyType_FromMetaclass,
which generalizes the existing :c:func:PyType_FromModuleAndSpec using
an additional metaclass argument.
(Contributed by Wenzel Jakob in :gh:93012.)
API for creating objects that can be called using
:ref:the vectorcall protocol <vectorcall> was added to the
:ref:Limited API <stable>:
Py_TPFLAGS_HAVE_VECTORCALLPyVectorcall_NARGSPyVectorcall_CallvectorcallfuncThe :c:macro:Py_TPFLAGS_HAVE_VECTORCALL flag is now removed from a class
when the class's :py:meth:~object.__call__ method is reassigned.
This makes vectorcall safe to use with mutable types (i.e. heap types
without the immutable flag, :c:macro:Py_TPFLAGS_IMMUTABLETYPE).
Mutable types that do not override :c:member:~PyTypeObject.tp_call now
inherit the Py_TPFLAGS_HAVE_VECTORCALL flag.
(Contributed by Petr Viktorin in :gh:93274.)
The :c:macro:Py_TPFLAGS_MANAGED_DICT and :c:macro:Py_TPFLAGS_MANAGED_WEAKREF
flags have been added. This allows extensions classes to support object
:attr:~object.__dict__ and weakrefs with less bookkeeping,
using less memory and with faster access.
API for performing calls using
:ref:the vectorcall protocol <vectorcall> was added to the
:ref:Limited API <stable>:
PyObject_VectorcallPyObject_VectorcallMethodPY_VECTORCALL_ARGUMENTS_OFFSETThis means that both the incoming and outgoing ends of the vector call
protocol are now available in the :ref:Limited API <stable>. (Contributed
by Wenzel Jakob in :gh:98586.)
Add two new public functions,
:c:func:PyEval_SetProfileAllThreads and
:c:func:PyEval_SetTraceAllThreads, that allow to set tracing and profiling
functions in all running threads in addition to the calling one. (Contributed
by Pablo Galindo in :gh:93503.)
Add new function :c:func:PyFunction_SetVectorcall to the C API
which sets the vectorcall field of a given :c:type:PyFunctionObject.
(Contributed by Andrew Frost in :gh:92257.)
The C API now permits registering callbacks via :c:func:PyDict_AddWatcher,
:c:func:PyDict_Watch and related APIs to be called whenever a dictionary
is modified. This is intended for use by optimizing interpreters, JIT
compilers, or debuggers.
(Contributed by Carl Meyer in :gh:91052.)
Add :c:func:PyType_AddWatcher and :c:func:PyType_Watch API to register
callbacks to receive notification on changes to a type.
(Contributed by Carl Meyer in :gh:91051.)
Add :c:func:PyCode_AddWatcher and :c:func:PyCode_ClearWatcher
APIs to register callbacks to receive notification on creation and
destruction of code objects.
(Contributed by Itamar Oren in :gh:91054.)
Add :c:func:PyFrame_GetVar and :c:func:PyFrame_GetVarString functions to
get a frame variable by its name.
(Contributed by Victor Stinner in :gh:91248.)
Add :c:func:PyErr_GetRaisedException and :c:func:PyErr_SetRaisedException
for saving and restoring the current exception.
These functions return and accept a single exception object,
rather than the triple arguments of the now-deprecated
:c:func:PyErr_Fetch and :c:func:PyErr_Restore.
This is less error prone and a bit more efficient.
(Contributed by Mark Shannon in :gh:101578.)
Add _PyErr_ChainExceptions1, which takes an exception instance,
to replace the legacy-API _PyErr_ChainExceptions, which is now
deprecated. (Contributed by Mark Shannon in :gh:101578.)
Add :c:func:PyException_GetArgs and :c:func:PyException_SetArgs
as convenience functions for retrieving and modifying
the :attr:~BaseException.args passed to the exception's constructor.
(Contributed by Mark Shannon in :gh:101578.)
Add :c:func:PyErr_DisplayException, which takes an exception instance,
to replace the legacy-api :c:func:!PyErr_Display. (Contributed by
Irit Katriel in :gh:102755).
.. _whatsnew312-pep683:
:pep:683: Introduce Immortal Objects, which allows objects
to bypass reference counts, and related changes to the C-API:
_Py_IMMORTAL_REFCNT: The reference count that defines an object
as immortal._Py_IsImmortal Checks if an object has the immortal reference count.PyObject_HEAD_INIT This will now initialize reference count to
_Py_IMMORTAL_REFCNT when used with Py_BUILD_CORE.SSTATE_INTERNED_IMMORTAL An identifier for interned unicode objects
that are immortal.SSTATE_INTERNED_IMMORTAL_STATIC An identifier for interned unicode
objects that are immortal and staticsys.getunicodeinternedsize This returns the total number of unicode
objects that have been interned. This is now needed for :file:refleak.py to
correctly track reference counts and allocated blocks(Contributed by Eddie Elizondo in :gh:84436.)
:pep:684: Add the new :c:func:Py_NewInterpreterFromConfig
function and :c:type:PyInterpreterConfig, which may be used
to create sub-interpreters with their own GILs.
(See :ref:whatsnew312-pep684 for more info.)
(Contributed by Eric Snow in :gh:104110.)
In the limited C API version 3.12, :c:func:Py_INCREF and
:c:func:Py_DECREF functions are now implemented as opaque function calls to
hide implementation details.
(Contributed by Victor Stinner in :gh:105387.)
Legacy Unicode APIs based on Py_UNICODE* representation has been removed.
Please migrate to APIs based on UTF-8 or wchar_t*.
Argument parsing functions like :c:func:PyArg_ParseTuple doesn't support
Py_UNICODE* based format (e.g. u, Z) anymore. Please migrate
to other formats for Unicode like s, z, es, and U.
tp_weaklist for all static builtin types is always NULL.
This is an internal-only field on PyTypeObject
but we're pointing out the change in case someone happens to be
accessing the field directly anyway. To avoid breakage, consider
using the existing public C-API instead, or, if necessary, the
(internal-only) _PyObject_GET_WEAKREFS_LISTPTR() macro.
This internal-only :c:member:PyTypeObject.tp_subclasses may now not be
a valid object pointer. Its type was changed to :c:expr:void * to
reflect this. We mention this in case someone happens to be accessing the
internal-only field directly.
To get a list of subclasses, call the Python method
:py:meth:~type.__subclasses__ (using :c:func:PyObject_CallMethod,
for example).
Add support of more formatting options (left aligning, octals, uppercase
hexadecimals, :c:type:intmax_t, :c:type:ptrdiff_t, :c:type:wchar_t C
strings, variable width and precision) in :c:func:PyUnicode_FromFormat and
:c:func:PyUnicode_FromFormatV.
(Contributed by Serhiy Storchaka in :gh:98836.)
An unrecognized format character in :c:func:PyUnicode_FromFormat and
:c:func:PyUnicode_FromFormatV now sets a :exc:SystemError.
In previous versions it caused all the rest of the format string to be
copied as-is to the result string, and any extra arguments discarded.
(Contributed by Serhiy Storchaka in :gh:95781.)
Fix wrong sign placement in :c:func:PyUnicode_FromFormat and
:c:func:PyUnicode_FromFormatV.
(Contributed by Philip Georgi in :gh:95504.)
Extension classes wanting to add a :attr:~object.__dict__ or weak reference slot
should use :c:macro:Py_TPFLAGS_MANAGED_DICT and
:c:macro:Py_TPFLAGS_MANAGED_WEAKREF instead of tp_dictoffset and
tp_weaklistoffset, respectively.
The use of tp_dictoffset and tp_weaklistoffset is still
supported, but does not fully support multiple inheritance
(:gh:95589), and performance may be worse.
Classes declaring :c:macro:Py_TPFLAGS_MANAGED_DICT must call
:c:func:!_PyObject_VisitManagedDict and :c:func:!_PyObject_ClearManagedDict
to traverse and clear their instance's dictionaries.
To clear weakrefs, call :c:func:PyObject_ClearWeakRefs, as before.
The :c:func:PyUnicode_FSDecoder function no longer accepts bytes-like
paths, like :class:bytearray and :class:memoryview types: only the exact
:class:bytes type is accepted for bytes strings.
(Contributed by Victor Stinner in :gh:98393.)
The :c:macro:Py_CLEAR, :c:macro:Py_SETREF and :c:macro:Py_XSETREF
macros now only evaluate their arguments once. If an argument has side
effects, these side effects are no longer duplicated.
(Contributed by Victor Stinner in :gh:98724.)
The interpreter's error indicator is now always normalized. This means
that :c:func:PyErr_SetObject, :c:func:PyErr_SetString and the other
functions that set the error indicator now normalize the exception
before storing it. (Contributed by Mark Shannon in :gh:101578.)
_Py_RefTotal is no longer authoritative and only kept around
for ABI compatibility. Note that it is an internal global and only
available on debug builds. If you happen to be using it then you'll
need to start using _Py_GetGlobalRefTotal().
The following functions now select an appropriate metaclass for the newly created type:
PyType_FromSpecPyType_FromSpecWithBasesPyType_FromModuleAndSpecCreating classes whose metaclass overrides :c:member:~PyTypeObject.tp_new
is deprecated, and in Python 3.14+ it will be disallowed.
Note that these functions ignore tp_new of the metaclass, possibly
allowing incomplete initialization.
Note that :c:func:PyType_FromMetaclass (added in Python 3.12)
already disallows creating classes whose metaclass overrides tp_new
(:meth:~object.__new__ in Python).
Since tp_new overrides almost everything PyType_From* functions do,
the two are incompatible with each other.
The existing behavior -- ignoring the metaclass for several steps
of type creation -- is unsafe in general, since (meta)classes assume that
tp_new was called.
There is no simple general workaround. One of the following may work for you:
If you control the metaclass, avoid using tp_new in it:
~PyTypeObject.tp_init instead.tp_new to NULL using
the :c:macro:Py_TPFLAGS_DISALLOW_INSTANTIATION flag.
This makes it acceptable for PyType_From* functions.Avoid PyType_From* functions: if you don't need C-specific features
(slots or setting the instance size), create types by :ref:calling <call>
the metaclass.
If you know the tp_new can be skipped safely, filter the deprecation
warning out using :func:warnings.catch_warnings from Python.
:c:var:PyOS_InputHook and :c:var:PyOS_ReadlineFunctionPointer are no
longer called in :ref:subinterpreters <sub-interpreter-support>. This is
because clients generally rely on process-wide global state (since these
callbacks have no way of recovering extension module state).
This also avoids situations where extensions may find themselves running in a
subinterpreter that they don't support (or haven't yet been loaded in). See
:gh:104668 for more info.
:c:struct:PyLongObject has had its internals changed for better performance.
Although the internals of :c:struct:PyLongObject are private, they are used
by some extension modules.
The internal fields should no longer be accessed directly, instead the API
functions beginning PyLong_... should be used instead.
Two new unstable API functions are provided for efficient access to the
value of :c:struct:PyLongObject\s which fit into a single machine word:
PyUnstable_Long_IsCompactPyUnstable_Long_CompactValueCustom allocators, set via :c:func:PyMem_SetAllocator, are now
required to be thread-safe, regardless of memory domain. Allocators
that don't have their own state, including "hooks", are not affected.
If your custom allocator is not already thread-safe and you need
guidance then please create a new GitHub issue
and CC @ericsnowcurrently.
In accordance with :pep:699, the ma_version_tag field in :c:type:PyDictObject
is deprecated for extension modules. Accessing this field will generate a compiler
warning at compile time. This field will be removed in Python 3.14.
(Contributed by Ramvikrams and Kumar Aditya in :gh:101193. PEP by Ken Jin.)
Deprecate global configuration variable:
Py_DebugFlag: use :c:member:PyConfig.parser_debugPy_VerboseFlag: use :c:member:PyConfig.verbosePy_QuietFlag: use :c:member:PyConfig.quietPy_InteractiveFlag: use :c:member:PyConfig.interactivePy_InspectFlag: use :c:member:PyConfig.inspectPy_OptimizeFlag: use :c:member:PyConfig.optimization_levelPy_NoSiteFlag: use :c:member:PyConfig.site_importPy_BytesWarningFlag: use :c:member:PyConfig.bytes_warningPy_FrozenFlag: use :c:member:PyConfig.pathconfig_warningsPy_IgnoreEnvironmentFlag: use :c:member:PyConfig.use_environmentPy_DontWriteBytecodeFlag: use :c:member:PyConfig.write_bytecodePy_NoUserSiteDirectory: use :c:member:PyConfig.user_site_directoryPy_UnbufferedStdioFlag: use :c:member:PyConfig.buffered_stdioPy_HashRandomizationFlag: use :c:member:PyConfig.use_hash_seed
and :c:member:PyConfig.hash_seedPy_IsolatedFlag: use :c:member:PyConfig.isolatedPy_LegacyWindowsFSEncodingFlag: use :c:member:PyPreConfig.legacy_windows_fs_encodingPy_LegacyWindowsStdioFlag: use :c:member:PyConfig.legacy_windows_stdio!Py_FileSystemDefaultEncoding: use :c:member:PyConfig.filesystem_encoding!Py_HasFileSystemDefaultEncoding: use :c:member:PyConfig.filesystem_encoding!Py_FileSystemDefaultEncodeErrors: use :c:member:PyConfig.filesystem_errors!Py_UTF8Mode: use :c:member:PyPreConfig.utf8_mode (see :c:func:Py_PreInitialize)The :c:func:Py_InitializeFromConfig API should be used with
:c:type:PyConfig instead.
(Contributed by Victor Stinner in :gh:77782.)
Creating :c:data:immutable types <Py_TPFLAGS_IMMUTABLETYPE> with mutable
bases is deprecated and will be disabled in Python 3.14. (:gh:95388)
The :file:structmember.h header is deprecated, though it continues to be
available and there are no plans to remove it.
Its contents are now available just by including :file:Python.h,
with a Py prefix added if it was missing:
PyMemberDef, :c:func:PyMember_GetOne and
:c:func:PyMember_SetOnePy_T_INT, :c:macro:Py_T_DOUBLE, etc.
(previously T_INT, T_DOUBLE, etc.)Py_READONLY (previously READONLY) and
:c:macro:Py_AUDIT_READ (previously all uppercase)Several items are not exposed from :file:Python.h:
T_OBJECT (use :c:macro:Py_T_OBJECT_EX)T_NONE (previously undocumented, and pretty quirky)WRITE_RESTRICTED which does nothing.RESTRICTED and READ_RESTRICTED, equivalents of
:c:macro:Py_AUDIT_READ.<stddef.h> is not included from :file:Python.h.
It should be included manually when using offsetof().The deprecated header continues to provide its original contents under the original names. Your old code can stay unchanged, unless the extra include and non-namespaced macros bother you greatly.
(Contributed in :gh:47146 by Petr Viktorin, based on
earlier work by Alexander Belopolsky and Matthias Braun.)
:c:func:PyErr_Fetch and :c:func:PyErr_Restore are deprecated.
Use :c:func:PyErr_GetRaisedException and
:c:func:PyErr_SetRaisedException instead.
(Contributed by Mark Shannon in :gh:101578.)
:c:func:!PyErr_Display is deprecated. Use :c:func:PyErr_DisplayException
instead. (Contributed by Irit Katriel in :gh:102755).
_PyErr_ChainExceptions is deprecated. Use _PyErr_ChainExceptions1
instead. (Contributed by Irit Katriel in :gh:102192.)
Using :c:func:PyType_FromSpec, :c:func:PyType_FromSpecWithBases
or :c:func:PyType_FromModuleAndSpec to create a class whose metaclass
overrides :c:member:~PyTypeObject.tp_new is deprecated.
Call the metaclass instead.
.. Add deprecations above alphabetically, not here at the end.
.. include:: ../deprecations/c-api-pending-removal-in-3.14.rst
.. include:: ../deprecations/c-api-pending-removal-in-3.15.rst
.. include:: ../deprecations/c-api-pending-removal-in-3.16.rst
.. include:: ../deprecations/c-api-pending-removal-in-future.rst
Remove the :file:token.h header file. There was never any public tokenizer C
API. The :file:token.h header file was only designed to be used by Python
internals.
(Contributed by Victor Stinner in :gh:92651.)
Legacy Unicode APIs have been removed. See :pep:623 for detail.
!PyUnicode_WCHAR_KIND!PyUnicode_AS_UNICODE!PyUnicode_AsUnicode!PyUnicode_AsUnicodeAndSize!PyUnicode_AS_DATA!PyUnicode_FromUnicode!PyUnicode_GET_SIZE!PyUnicode_GetSize!PyUnicode_GET_DATA_SIZERemove the PyUnicode_InternImmortal() function macro.
(Contributed by Victor Stinner in :gh:85858.)