What's New In Python 3.12

Editor
Adam Turner

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* 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.)

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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 12345.)

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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 changelog <changelog>.

693 -- Python 3.12 Release Schedule

Summary -- Release highlights

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 !distutils package has been removed from the standard library. Filesystem support in os and pathlib has seen a number of improvements, and several modules have better performance.

The language changes focus on usability, as f-strings <f-string> have had many limitations removed and 'Did you mean ...' suggestions continue to improve. The new type parameter syntax <whatsnew312-pep695> and type statement improve ergonomics for using generic types <generic type> and 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 Library Reference <library-index> and 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.

New syntax features:

PEP 695 <whatsnew312-pep695>, type parameter syntax and the type statement

New grammar features:

PEP 701 <whatsnew312-pep701>, f-strings <f-string> in the grammar

Interpreter improvements:

PEP 684 <whatsnew312-pep684>, a unique per-interpreter GIL <global interpreter lock>
PEP 669 <whatsnew312-pep669>, low impact monitoring
Improved 'Did you mean ...' suggestions for NameError, ImportError, and SyntaxError exceptions

Python data model improvements:

PEP 688 <whatsnew312-pep688>, using the buffer protocol <bufferobjects> from Python

Significant improvements in the standard library:

The pathlib.Path class now supports subclassing
The os module received several improvements for Windows support
A command-line interface <sqlite3-cli> has been added to the sqlite3 module
isinstance checks against runtime-checkable protocols <typing.runtime_checkable> enjoy a speed up of between two and 20 times
The asyncio package has had a number of performance improvements, with some benchmarks showing a 75% speed up.
A command-line interface <uuid-cli> has been added to the uuid module
Due to the changes in PEP 701 <whatsnew312-pep701>, producing tokens via the tokenize module is up to 64% faster.

Security improvements:

Replace the builtin hashlib implementations of SHA1, SHA3, SHA2-384, SHA2-512, and MD5 with formally verified code from the HACL* 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 tier
PEP 683 <whatsnew312-pep683>, immortal objects

CPython implementation improvements:

PEP 709 <whatsnew312-pep709>, comprehension inlining
CPython support <perf_profiling> for the Linux perf profiler
Implement stack overflow protection on supported platforms

New typing features:

PEP 692 <whatsnew312-pep692>, using ~typing.TypedDict to annotate **kwargs <argument>
PEP 698 <whatsnew312-pep698>, typing.override decorator

Important deprecations, removals or restrictions:

623: Remove wstr from Unicode objects in Python's C API, reducing the size of every str object by at least 8 bytes.
632: Remove the !distutils package. See the migration guide <0632#migration-advice> for advice replacing the APIs it provided. The third-party Setuptools package continues to provide !distutils, if you still require it in Python 3.12 and beyond.
95299: Do not pre-install setuptools in virtual environments created with 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 activated <venv-explanation> virtual environment.
The !asynchat, !asyncore, and !imp modules have been removed, along with several unittest.TestCase method aliases.

New Features

PEP 695: Type Parameter Syntax

Generic classes and functions under 484 were declared using a verbose syntax that left the scope of type parameters unclear and required explicit declarations of variance.

695 introduces a new, more compact and explicit way to create generic classes <generic-classes> and 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 type aliases <type-aliases> using the type statement, which creates an instance of ~typing.TypeAliasType:

type Point = tuple[float, float]

Type aliases can also be generic <generic-type-aliases>:

type Point[T] = tuple[T, T]

The new syntax allows declaring ~typing.TypeVarTuple and ~typing.ParamSpec parameters, as well as ~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 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 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 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, annotations <annotation> will also be evaluated in annotation scopes.

See 695 for more details.

(PEP written by Eric Traut. Implementation by Jelle Zijlstra, Eric Traut, and others in 103764.)

PEP 701: Syntactic formalization of f-strings

701 lifts some restrictions on the usage of 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 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 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 701 for more details.

As a positive side-effect of how this feature has been implemented (by parsing f-strings with 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 SyntaxError:

>>> 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:

>>> 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 102856. PEP written by Pablo Galindo, Batuhan Taskaya, Lysandros Nikolaou and Marta Gómez).

PEP 684: A Per-Interpreter GIL

684 introduces a per-interpreter 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 anticipated for 3.13 <554>.

Use the new Py_NewInterpreterFromConfig function to create an interpreter with its own GIL:

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 104210, etc.)

PEP 669: Low impact monitoring for CPython

669 defines a new 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 sys.monitoring for details.

(Contributed by Mark Shannon in 103082.)

PEP 688: Making the buffer protocol accessible in Python

688 introduces a way to use the buffer protocol <bufferobjects> from Python code. Classes that implement the ~object.__buffer__ method are now usable as buffer types.

The new collections.abc.Buffer ABC provides a standard way to represent buffer objects, for example in type annotations. The new inspect.BufferFlags enum represents the flags that can be used to customize buffer creation. (Contributed by Jelle Zijlstra in 102500.)

PEP 709: Comprehension inlining

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 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:

There is no longer a separate frame for the comprehension in tracebacks, and tracing/profiling no longer shows the comprehension as a function call.
The 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.
Calling locals inside a comprehension now includes variables from outside the comprehension, and no longer includes the synthetic .0 variable for the comprehension "argument".
A comprehension iterating directly over 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 709.)

Improved Error Messages

Modules from the standard library are now potentially suggested as part of the error messages displayed by the interpreter when a NameError is raised to the top level. (Contributed by Pablo Galindo in 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 NameError exceptions for instances. Now if a 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 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 SyntaxError error message when the user types import x from y instead of from y import x. (Contributed by Pablo Galindo in 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?
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 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 type hints <484> and the typing module.

PEP 692: Using `TypedDict` for more precise `**kwargs` typing

Typing **kwargs in a function signature as introduced by 484 allowed for valid annotations only in cases where all of the **kwargs were of the same type.

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 692 for more details.

(Contributed by Franek Magiera in 103629.)

PEP 698: Override Decorator for Static Typing

A new decorator typing.override has been added to the 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 698 for more details.

(Contributed by Steven Troxler in 101561.)

Other Language Changes

The parser now raises SyntaxError when parsing source code containing null bytes. (Contributed by Pablo Galindo in 96670.)
A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning, instead of DeprecationWarning. For example, re.compile("\d+\.\d+") now emits a SyntaxWarning ("\d" is an invalid escape sequence, use raw strings for regular expression: re.compile(r"\d+\.\d+")). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning. (Contributed by Victor Stinner in 98401.)
Octal escapes with value larger than 0o377 (ex: "\477"), deprecated in Python 3.11, now produce a SyntaxWarning, instead of DeprecationWarning. In a future Python version they will be eventually a SyntaxError. (Contributed by Victor Stinner in 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 572. (Contributed by Nikita Sobolev in 100581.)
Exceptions raised in a class or type's __set_name__ method are no longer wrapped by a RuntimeError. Context information is added to the exception as a 678 note. (Contributed by Irit Katriel in 77757.)
When a try-except* construct handles the entire ExceptionGroup and raises one other exception, that exception is no longer wrapped in an ExceptionGroup. Also changed in version 3.11.4. (Contributed by Irit Katriel in 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 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 97922.)
All builtin and extension callables expecting boolean parameters now accept arguments of any type instead of just bool and int. (Contributed by Serhiy Storchaka in 60203.)
memoryview now supports the half-float type (the "e" format code). (Contributed by Donghee Na and Antoine Pitrou in 90751.)
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 101264.)
sum now uses Neumaier summation to improve accuracy and commutativity when summing floats or mixed ints and floats. (Contributed by Raymond Hettinger in 100425.)
ast.parse now raises SyntaxError instead of ValueError when parsing source code containing null bytes. (Contributed by Pablo Galindo in 96670.)
The extraction methods in tarfile, and 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 tarfile extraction filters <tarfile-extraction-filter> for details. In Python 3.14, the default will switch to 'data'. (Contributed by Petr Viktorin in 706.)
types.MappingProxyType instances are now hashable if the underlying mapping is hashable. (Contributed by Serhiy Storchaka in 87995.)
Add support for the perf profiler <perf_profiling> through the new environment variable PYTHONPERFSUPPORT and command-line option -X perf <-X>, as well as the new sys.activate_stack_trampoline, sys.deactivate_stack_trampoline, and 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 96123.)

New Modules

None.

Improved Modules

array

The array.array class now supports subscripting, making it a generic type. (Contributed by Jelle Zijlstra in 98658.)

asyncio

The performance of writing to sockets in asyncio has been significantly improved. asyncio now avoids unnecessary copying when writing to sockets and uses ~socket.socket.sendmsg if the platform supports it. (Contributed by Kumar Aditya in 91166.)
Add asyncio.eager_task_factory and 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 102853, 104140, and 104138)
On Linux, asyncio uses !asyncio.PidfdChildWatcher by default if os.pidfd_open is available and functional instead of !asyncio.ThreadedChildWatcher. (Contributed by Kumar Aditya in 98024.)
The event loop now uses the best available child watcher for each platform (!asyncio.PidfdChildWatcher if supported and !asyncio.ThreadedChildWatcher otherwise), so manually configuring a child watcher is not recommended. (Contributed by Kumar Aditya in 94597.)
Add loop_factory parameter to asyncio.run to allow specifying a custom event loop factory. (Contributed by Kumar Aditya in 99388.)
Add C implementation of asyncio.current_task for 4x-6x speedup. (Contributed by Itamar Oren and Pranav Thulasiram Bhat in 100344.)
asyncio.iscoroutine now returns False for generators as asyncio does not support legacy generator-based coroutines. (Contributed by Kumar Aditya in 102748.)
asyncio.wait and asyncio.as_completed now accepts generators yielding tasks. (Contributed by Kumar Aditya in 78530.)

calendar

Add enums calendar.Month and calendar.Day defining months of the year and days of the week. (Contributed by Prince Roshan in 103636.)

csv

Add csv.QUOTE_NOTNULL and csv.QUOTE_STRINGS flags to provide finer grained control of None and empty strings by ~csv.reader and ~csv.writer objects.

dis

Pseudo instruction opcodes (which are used by the compiler but do not appear in executable bytecode) are now exposed in the dis module. HAVE_ARGUMENT is still relevant to real opcodes, but it is not useful for pseudo instructions. Use the new dis.hasarg collection instead. (Contributed by Irit Katriel in 94216.)
Add the dis.hasexc collection to signify instructions that set an exception handler. (Contributed by Irit Katriel in 94216.)

fractions

Objects of type fractions.Fraction now support float-style formatting. (Contributed by Mark Dickinson in 100161.)

importlib.resources

importlib.resources.as_file now supports resource directories. (Contributed by Jason R. Coombs in 97930.)
Rename first parameter of importlib.resources.files to anchor. (Contributed by Jason R. Coombs in 100598.)

inspect

Add inspect.markcoroutinefunction to mark sync functions that return a coroutine for use with inspect.iscoroutinefunction. (Contributed by Carlton Gibson in 99247.)
Add inspect.getasyncgenstate and inspect.getasyncgenlocals for determining the current state of asynchronous generators. (Contributed by Thomas Krennwallner in 79940.)
The performance of 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 103193.)

itertools

Add itertools.batched for collecting into even-sized tuples where the last batch may be shorter than the rest. (Contributed by Raymond Hettinger in 98363.)

math

Add math.sumprod for computing a sum of products. (Contributed by Raymond Hettinger in 100485.)
Extend 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 94906.)

os

Add os.PIDFD_NONBLOCK to open a file descriptor for a process with os.pidfd_open in non-blocking mode. (Contributed by Kumar Aditya in 93312.)
os.DirEntry now includes an os.DirEntry.is_junction method to check if the entry is a junction. (Contributed by Charles Machalow in 99547.)
Add os.listdrives, os.listvolumes and os.listmounts functions on Windows for enumerating drives, volumes and mount points. (Contributed by Steve Dower in 102519.)
os.stat and 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 99726.)

os.path

Add os.path.isjunction to check if a given path is a junction. (Contributed by Charles Machalow in 99547.)
Add os.path.splitroot to split a path into a triad (drive, root, tail). (Contributed by Barney Gale in 101000.)

pathlib

Add support for subclassing pathlib.PurePath and pathlib.Path, plus their Posix- and Windows-specific variants. Subclasses may override the pathlib.PurePath.with_segments method to pass information between path instances.
Add pathlib.Path.walk for walking the directory trees and generating all file or directory names within them, similar to os.walk. (Contributed by Stanislav Zmiev in 90385.)
Add walk_up optional parameter to pathlib.PurePath.relative_to to allow the insertion of .. entries in the result; this behavior is more consistent with os.path.relpath. (Contributed by Domenico Ragusa in 84538.)
Add pathlib.Path.is_junction as a proxy to os.path.isjunction. (Contributed by Charles Machalow in 99547.)
Add case_sensitive optional parameter to pathlib.Path.glob, pathlib.Path.rglob and pathlib.PurePath.match for matching the path's case sensitivity, allowing for more precise control over the matching process.

platform

Add support for detecting Windows 11 and Windows Server releases past 2012. Previously, lookups on Windows Server platforms newer than Windows Server 2012 and on Windows 11 would return Windows-10. (Contributed by Steve Dower in 89545.)

pdb

Add convenience variables to hold values temporarily for debug session and provide quick access to values like the current frame or the return value. (Contributed by Tian Gao in 103693.)

random

Add random.binomialvariate. (Contributed by Raymond Hettinger in 81620.)
Add a default of lambd=1.0 to random.expovariate. (Contributed by Raymond Hettinger in 100234.)

shutil

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 74696.)
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 102828.)
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 103179.)

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 103179.)

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 103179.)

sqlite3

Add a command-line interface <sqlite3-cli>. (Contributed by Erlend E. Aasland in 77617.)
Add the sqlite3.Connection.autocommit attribute to sqlite3.Connection and the autocommit parameter to sqlite3.connect to control 249-compliant transaction handling <sqlite3-transaction-control-autocommit>. (Contributed by Erlend E. Aasland in 83638.)
Add entrypoint keyword-only parameter to sqlite3.Connection.load_extension, for overriding the SQLite extension entry point. (Contributed by Erlend E. Aasland in 103015.)
Add sqlite3.Connection.getconfig and sqlite3.Connection.setconfig to sqlite3.Connection to make configuration changes to a database connection. (Contributed by Erlend E. Aasland in 103489.)

statistics

Extend statistics.correlation to include as a ranked method for computing the Spearman correlation of ranked data. (Contributed by Raymond Hettinger in 95861.)

sys

Add the sys.monitoring namespace to expose the new PEP 669 <whatsnew312-pep669> monitoring API. (Contributed by Mark Shannon in 103082.)
Add sys.activate_stack_trampoline and sys.deactivate_stack_trampoline for activating and deactivating stack profiler trampolines, and 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 96123.)
Add 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: sys.last_type, sys.last_value and sys.last_traceback. (Contributed by Irit Katriel in 102778.)
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 103176.)
sys.setrecursionlimit and 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

The tempfile.NamedTemporaryFile function has a new optional parameter delete_on_close (Contributed by Evgeny Zorin in 58451.)
tempfile.mkdtemp now always returns an absolute path, even if the argument provided to the dir parameter is a relative path.

threading

Add threading.settrace_all_threads and 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 93503.)

tkinter

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 94473.)

tokenize

The tokenize module includes the changes introduced in 701. (Contributed by Marta Gómez Macías and Pablo Galindo in 102856.) See whatsnew312-porting-to-python312 for more information on the changes to the tokenize module.

types

Add types.get_original_bases to allow for further introspection of user-defined-generics when subclassed. (Contributed by James Hilton-Balfe and Alex Waygood in 101827.)

typing

isinstance checks against runtime-checkable protocols <typing.runtime_checkable> now use inspect.getattr_static rather than hasattr to lookup whether attributes exist. This means that descriptors and ~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 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 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 isinstance checks against 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 74690 and 103193.)
All typing.TypedDict and typing.NamedTuple classes now have the __orig_bases__ attribute. (Contributed by Adrian Garcia Badaracco in 103699.)
Add frozen_default parameter to typing.dataclass_transform. (Contributed by Erik De Bonte in 99957.)

unicodedata

The Unicode database has been updated to version 15.0.0. (Contributed by Benjamin Peterson in 96734).

unittest

Add a --durations command line option, showing the N slowest test cases:

python3 -m unittest --durations=3 lib.tests.test_threading
.....
Slowest test durations
----------------------------------------------------------------------
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)

(0.000 durations hidden.  Use -v to show these durations.)
----------------------------------------------------------------------
Ran 158 tests in 9.869s

OK (skipped=3)

(Contributed by Giampaolo Rodola in 48330)

uuid

Add a command-line interface <uuid-cli>. (Contributed by Adam Chhina in 88597.)

Optimizations

Remove wstr and wstr_length members from Unicode objects. It reduces object size by 8 or 16 bytes on 64bit platform. (623) (Contributed by Inada Naoki in 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 90536 and tuned by Donghee Na in 101525)
Speed up the regular expression substitution (functions re.sub and re.subn and corresponding !re.Pattern methods) for replacement strings containing group references by 2--3 times. (Contributed by Serhiy Storchaka in 91524.)
Speed up asyncio.Task creation by deferring expensive string formatting. (Contributed by Itamar Oren in 103793.)
The tokenize.tokenize and tokenize.generate_tokens functions are up to 64% faster as a side effect of the changes required to cover 701 in the tokenize module. (Contributed by Marta Gómez Macías and Pablo Galindo in 102856.)
Speed up super method calls and attribute loads via the new LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and Vladimir Matveev in 103497.)

CPython bytecode changes

Remove the !LOAD_METHOD instruction. It has been merged into LOAD_ATTR. LOAD_ATTR will now behave like the old !LOAD_METHOD instruction if the low bit of its oparg is set. (Contributed by Ken Jin in 93429.)
Remove the !JUMP_IF_FALSE_OR_POP and !JUMP_IF_TRUE_OR_POP instructions. (Contributed by Irit Katriel in 102859.)
Remove the !PRECALL instruction. (Contributed by Mark Shannon in 92925.)
Add the BINARY_SLICE and STORE_SLICE instructions. (Contributed by Mark Shannon in 94163.)
Add the CALL_INTRINSIC_1 instructions. (Contributed by Mark Shannon in 99005.)
Add the CALL_INTRINSIC_2 instruction. (Contributed by Irit Katriel in 101799.)
Add the CLEANUP_THROW instruction. (Contributed by Brandt Bucher in 90997.)
Add the !END_SEND instruction. (Contributed by Mark Shannon in 103082.)
Add the LOAD_FAST_AND_CLEAR instruction as part of the implementation of 709. (Contributed by Carl Meyer in 101441.)
Add the LOAD_FAST_CHECK instruction. (Contributed by Dennis Sweeney in 93143.)
Add the LOAD_FROM_DICT_OR_DEREF, LOAD_FROM_DICT_OR_GLOBALS, and LOAD_LOCALS opcodes as part of the implementation of 695. Remove the !LOAD_CLASSDEREF opcode, which can be replaced with LOAD_LOCALS plus LOAD_FROM_DICT_OR_DEREF. (Contributed by Jelle Zijlstra in 103764.)
Add the LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and Vladimir Matveev in 103497.)
Add the RETURN_CONST instruction. (Contributed by Wenyang Wang in 101632.)

Demos and Tools

Remove the Tools/demo/ directory which contained old demo scripts. A copy can be found in the old-demos project. (Contributed by Victor Stinner in 97681.)
Remove outdated example scripts of the Tools/scripts/ directory. A copy can be found in the old-demos project. (Contributed by Victor Stinner in 97669.)

Deprecated

argparse: The type, choices, and metavar parameters of !argparse.BooleanOptionalAction are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in 92248.)
ast: The following ast features have been deprecated in documentation since Python 3.8, now cause a 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.Ellipsis
Use ast.Constant instead. (Contributed by Serhiy Storchaka in 90953.)
asyncio:
- The child watcher classes !asyncio.MultiLoopChildWatcher, !asyncio.FastChildWatcher, !asyncio.AbstractChildWatcher and !asyncio.SafeChildWatcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in 94597.)
- !asyncio.set_child_watcher, !asyncio.get_child_watcher, !asyncio.AbstractEventLoopPolicy.set_child_watcher and !asyncio.AbstractEventLoopPolicy.get_child_watcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in 94597.)
- The ~asyncio.get_event_loop method of the default event loop policy now emits a DeprecationWarning if there is no current event loop set and it decides to create one. (Contributed by Serhiy Storchaka and Guido van Rossum in 100160.)
calendar: calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY. (Contributed by Prince Roshan in 103636.)
collections.abc: Deprecated collections.abc.ByteString.

Use isinstance(obj, collections.abc.Buffer) to test if obj implements the buffer protocol <bufferobjects> at runtime. For use in type annotations, either use ~collections.abc.Buffer or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).

!ByteString was originally intended to be an abstract class that would serve as a supertype of both bytes and bytearray. However, since the ABC never had any methods, knowing that an object was an instance of !ByteString never actually told you anything useful about the object. Other common buffer types such as memoryview were also never understood as subtypes of !ByteString (either at runtime or by static type checkers).

See PEP 688 <688#current-options> for more details. (Contributed by Shantanu Jain in 91896.)
datetime: datetime.datetime's ~datetime.datetime.utcnow and ~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 ~datetime.datetime.now and ~datetime.datetime.fromtimestamp with the tz parameter set to datetime.UTC. (Contributed by Paul Ganssle in 103857.)
email: Deprecate the isdst parameter in email.utils.localtime. (Contributed by Alan Williams in 72346.)
importlib.abc: Deprecated the following classes, scheduled for removal in Python 3.14:
- !importlib.abc.ResourceReader
- !importlib.abc.Traversable
- !importlib.abc.TraversableResources
Use importlib.resources.abc classes instead:
- importlib.resources.abc.Traversable
- importlib.resources.abc.TraversableResources
(Contributed by Jason R. Coombs and Hugo van Kemenade in 93963.)
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 101588.)
multiprocessing: In Python 3.14, the default multiprocessing start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default (84559). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the ~multiprocessing.get_context or ~multiprocessing.set_start_method APIs to explicitly specify when your code requires 'fork'. See contexts and start methods <multiprocessing-start-methods>.
pkgutil: !pkgutil.find_loader and !pkgutil.get_loader are deprecated and will be removed in Python 3.14; use importlib.util.find_spec instead. (Contributed by Nikita Sobolev in 97850.)
pty: The module has two undocumented master_open() and slave_open() functions that have been deprecated since Python 2 but only gained a proper DeprecationWarning in 3.12. Remove them in 3.14. (Contributed by Soumendra Ganguly and Gregory P. Smith in 85984.)
os:
- The st_ctime fields return by os.stat and 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 99726.)
- On POSIX platforms, os.fork can now raise a 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 os.fork documentation for more details along with this discussion on fork being incompatible with threads for why we're now surfacing this longstanding platform compatibility problem to developers.
When this warning appears due to usage of multiprocessing or concurrent.futures the fix is to use a different multiprocessing start method such as "spawn" or "forkserver".
shutil: The onerror argument of shutil.rmtree is deprecated; use onexc instead. (Contributed by Irit Katriel in 102828.)
sqlite3:
- default adapters and converters <sqlite3-default-converters> are now deprecated. Instead, use the sqlite3-adapter-converter-recipes and tailor them to your needs. (Contributed by Erlend E. Aasland in 90016.)
- In ~sqlite3.Cursor.execute, DeprecationWarning is now emitted when named placeholders <sqlite3-placeholders> are used together with parameters supplied as a sequence instead of as a dict. Starting from Python 3.14, using named placeholders with parameters supplied as a sequence will raise a ~sqlite3.ProgrammingError. (Contributed by Erlend E. Aasland in 101698.)
sys: The sys.last_type, sys.last_value and sys.last_traceback fields are deprecated. Use sys.last_exc instead. (Contributed by Irit Katriel in 102778.)
tarfile: Extracting tar archives without specifying filter is deprecated until Python 3.14, when 'data' filter will become the default. See tarfile-extraction-filter for details.
typing:
- typing.Hashable and typing.Sized, aliases for collections.abc.Hashable and collections.abc.Sized respectively, are deprecated. (94309.)
- typing.ByteString, deprecated since Python 3.9, now causes a DeprecationWarning to be emitted when it is used. (Contributed by Alex Waygood in 91896.)
xml.etree.ElementTree: The module now emits DeprecationWarning when testing the truth value of an xml.etree.ElementTree.Element. Before, the Python implementation emitted FutureWarning, and the C implementation emitted nothing. (Contributed by Jacob Walls in 83122.)
The 3-arg signatures (type, value, traceback) of coroutine throw() <coroutine.throw>, generator throw() <generator.throw> and 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 89874.)
DeprecationWarning is now raised when ~module.__package__ on a module differs from __spec__.parent <importlib.machinery.ModuleSpec.parent> (previously it was ImportWarning). (Contributed by Brett Cannon in 65961.)
Setting ~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 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 103487.)
Accessing !codeobject.co_lnotab on code objects was deprecated in Python 3.10 via 626, but it only got a proper DeprecationWarning in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in 101866.)

Pending removal in Python 3.13

Modules (see 594):

!aifc
!audioop
!cgi
!cgitb
!chunk
!crypt
!imghdr
!mailcap
!msilib
!nis
!nntplib
!ossaudiodev
!pipes
!sndhdr
!spwd
!sunau
!telnetlib
!uu
!xdrlib

Other modules:

!lib2to3, and the 2to3 program (84540)

APIs:

!configparser.LegacyInterpolation (90765)
locale.resetlocale() (90817)
!turtle.RawTurtle.settiltangle (50096)
!unittest.findTestCases (50096)
!unittest.getTestCaseNames (50096)
!unittest.makeSuite (50096)
!unittest.TestProgram.usageExit (67048)
!webbrowser.MacOSX (86421)
classmethod descriptor chaining (89519)

Pending removal in Python 3.14

argparse: The type, choices, and metavar parameters of !argparse.BooleanOptionalAction are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in 92248.)
ast: The following features have been deprecated in documentation since Python 3.8, now cause a 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.Ellipsis
Use ast.Constant instead. (Contributed by Serhiy Storchaka in 90953.)
asyncio:
- The child watcher classes !asyncio.MultiLoopChildWatcher, !asyncio.FastChildWatcher, !asyncio.AbstractChildWatcher and !asyncio.SafeChildWatcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in 94597.)
- !asyncio.set_child_watcher, !asyncio.get_child_watcher, !asyncio.AbstractEventLoopPolicy.set_child_watcher and !asyncio.AbstractEventLoopPolicy.get_child_watcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in 94597.)
- The ~asyncio.get_event_loop method of the default event loop policy now emits a DeprecationWarning if there is no current event loop set and it decides to create one. (Contributed by Serhiy Storchaka and Guido van Rossum in 100160.)
email: Deprecated the isdst parameter in email.utils.localtime. (Contributed by Alan Williams in 72346.)
importlib.abc deprecated classes:
- !importlib.abc.ResourceReader
- !importlib.abc.Traversable
- !importlib.abc.TraversableResources
Use importlib.resources.abc classes instead:
- importlib.resources.abc.Traversable
- importlib.resources.abc.TraversableResources
(Contributed by Jason R. Coombs and Hugo van Kemenade in 93963.)
itertools had undocumented, inefficient, historically buggy, and inconsistent support for copy, deepcopy, and pickle operations. This will be removed in 3.14 for a significant reduction in code volume and maintenance burden. (Contributed by Raymond Hettinger in 101588.)
multiprocessing: The default start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default (84559). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the ~multiprocessing.get_context or ~multiprocessing.set_start_method APIs to explicitly specify when your code requires 'fork'. See multiprocessing-start-methods.
pathlib: ~pathlib.PurePath.is_relative_to and ~pathlib.PurePath.relative_to: passing additional arguments is deprecated.
pkgutil: !pkgutil.find_loader and !pkgutil.get_loader now raise DeprecationWarning; use importlib.util.find_spec instead. (Contributed by Nikita Sobolev in 97850.)
pty:
- master_open(): use pty.openpty.
- slave_open(): use pty.openpty.
sqlite3:
- !version and !version_info.
- ~sqlite3.Cursor.execute and ~sqlite3.Cursor.executemany if named placeholders <sqlite3-placeholders> are used and parameters is a sequence instead of a dict.
urllib: !urllib.parse.Quoter is deprecated: it was not intended to be a public API. (Contributed by Gregory P. Smith in 88168.)

Pending removal in Python 3.15

The import system:
- Setting __cached__ on a module while failing to set __spec__.cached <importlib.machinery.ModuleSpec.cached> is deprecated. In Python 3.15, __cached__ will cease to be set or take into consideration by the import system or standard library. (97879)
ctypes:
- The undocumented !ctypes.SetPointerType function has been deprecated since Python 3.13.
http.server:
- The obsolete and rarely used !CGIHTTPRequestHandler has been deprecated since Python 3.13. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.
- The !--cgi flag to the python -m http.server command-line interface has been deprecated since Python 3.13.
importlib:
- load_module() method: use exec_module() instead.
pathlib:
- !.PurePath.is_reserved has been deprecated since Python 3.13. Use os.path.isreserved to detect reserved paths on Windows.
platform:
- !platform.java_ver has been deprecated since Python 3.13. This function is only useful for Jython support, has a confusing API, and is largely untested.
sysconfig:
- The check_home argument of sysconfig.is_python_build has been deprecated since Python 3.12.
threading:
- ~threading.RLock will take no arguments in Python 3.15. Passing any arguments has been deprecated since Python 3.14, as the Python version does not permit any arguments, but the C version allows any number of positional or keyword arguments, ignoring every argument.
types:
- types.CodeType: Accessing !codeobject.co_lnotab was deprecated in 626 since 3.10 and was planned to be removed in 3.12, but it only got a proper DeprecationWarning in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in 101866.)
typing:
- The undocumented keyword argument syntax for creating ~typing.NamedTuple classes (for example, Point = NamedTuple("Point", x=int, y=int)) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead.
- When using the functional syntax of ~typing.TypedDicts, failing to pass a value to the fields parameter (TD = TypedDict("TD")) or passing None (TD = TypedDict("TD", None)) has been deprecated since Python 3.13. Use class TD(TypedDict): pass or TD = TypedDict("TD", {}) to create a TypedDict with zero field.
- The !typing.no_type_check_decorator decorator function has been deprecated since Python 3.13. After eight years in the typing module, it has yet to be supported by any major type checker.
!sre_compile, !sre_constants and !sre_parse modules.
wave:
- The getmark(), setmark() and getmarkers() methods of the ~wave.Wave_read and ~wave.Wave_write classes have been deprecated since Python 3.13.
zipimport:
- !zipimport.zipimporter.load_module has been deprecated since Python 3.10. Use ~zipimport.zipimporter.exec_module instead. (125746.)

Pending removal in Python 3.16

The import system:
- Setting ~module.__loader__ on a module while failing to set __spec__.loader <importlib.machinery.ModuleSpec.loader> is deprecated. In Python 3.16, !__loader__ will cease to be set or taken into consideration by the import system or the standard library.
- Setting ~module.__package__ on a module while failing to set __spec__.parent <importlib.machinery.ModuleSpec.parent> is deprecated. In Python 3.16, !__package__ will cease to be taken into consideration by the import system or standard library. (97879)
The bundled copy of libmpdec.
array:
- The 'u' format code (wchar_t) has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use the 'w' format code (Py_UCS4) for Unicode characters instead.
asyncio:
- !asyncio.iscoroutinefunction is deprecated and will be removed in Python 3.16; use inspect.iscoroutinefunction instead. (Contributed by Jiahao Li and Kumar Aditya in 122875.)
- asyncio policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated:
  - !asyncio.AbstractEventLoopPolicy
  - !asyncio.DefaultEventLoopPolicy
  - !asyncio.WindowsSelectorEventLoopPolicy
  - !asyncio.WindowsProactorEventLoopPolicy
  - !asyncio.get_event_loop_policy
  - !asyncio.set_event_loop_policy
  Users should use asyncio.run or asyncio.Runner with loop_factory to use the desired event loop implementation.
  
  For example, to use asyncio.SelectorEventLoop on Windows:
```
import asyncio

async def main():
    ...

asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop)
```
  (Contributed by Kumar Aditya in 127949.)
builtins:
- Bitwise inversion on boolean types, ~True or ~False has been deprecated since Python 3.12, as it produces surprising and unintuitive results (-2 and -1). Use not x instead for the logical negation of a Boolean. In the rare case that you need the bitwise inversion of the underlying integer, convert to int explicitly (~int(x)).
functools:
- Calling the Python implementation of functools.reduce with function or sequence as keyword arguments has been deprecated since Python 3.14.
logging:
- Support for custom logging handlers with the strm argument is deprecated and scheduled for removal in Python 3.16. Define handlers with the stream argument instead. (Contributed by Mariusz Felisiak in 115032.)
mimetypes:
- Valid extensions start with a '.' or are empty for mimetypes.MimeTypes.add_type. Undotted extensions are deprecated and will raise a ValueError in Python 3.16. (Contributed by Hugo van Kemenade in 75223.)
shutil:
- The !ExecError exception has been deprecated since Python 3.14. It has not been used by any function in !shutil since Python 3.4, and is now an alias of RuntimeError.
symtable:
- The !symtable.Class.get_methods method has been deprecated since Python 3.14.
sys:
- The !_enablelegacywindowsfsencoding function has been deprecated since Python 3.13. Use the PYTHONLEGACYWINDOWSFSENCODING environment variable instead.
sysconfig:
- The !sysconfig.expand_makefile_vars function has been deprecated since Python 3.14. Use the vars argument of sysconfig.get_paths instead.
tarfile:
- The undocumented and unused !TarInfo.tarfile attribute has been deprecated since Python 3.13.

Pending removal in Python 3.17

datetime:
- ~datetime.datetime.strptime calls using a format string containing %e (day of month) without a year. This has been deprecated since Python 3.15. (Contributed by Stan Ulbrych in 70647.)
collections.abc:
- collections.abc.ByteString is scheduled for removal in Python 3.17.
  
  Use isinstance(obj, collections.abc.Buffer) to test if obj implements the buffer protocol <bufferobjects> at runtime. For use in type annotations, either use ~collections.abc.Buffer or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).
  
  !ByteString was originally intended to be an abstract class that would serve as a supertype of both bytes and bytearray. However, since the ABC never had any methods, knowing that an object was an instance of !ByteString never actually told you anything useful about the object. Other common buffer types such as memoryview were also never understood as subtypes of !ByteString (either at runtime or by static type checkers).
  
  See PEP 688 <688#current-options> for more details. (Contributed by Shantanu Jain in 91896.)
encodings:
- Passing non-ascii encoding names to encodings.normalize_encoding is deprecated and scheduled for removal in Python 3.17. (Contributed by Stan Ulbrych in 136702.)
profile:
- The !profile module is deprecated and will be removed in Python 3.17. Use profiling.tracing instead, which provides a compatible API. See 799 for details. (Contributed by Pablo Galindo and László Kiss Kollár in 138122.)
webbrowser:
- !webbrowser.MacOSXOSAScript is deprecated in favour of !webbrowser.MacOS. (137586)
typing:
- Before Python 3.14, old-style unions were implemented using the private class typing._UnionGenericAlias. This class is no longer needed for the implementation, but it has been retained for backward compatibility, with removal scheduled for Python 3.17. Users should use documented introspection helpers like typing.get_origin and typing.get_args instead of relying on private implementation details.
- typing.ByteString, deprecated since Python 3.9, is scheduled for removal in Python 3.17.
  
  Use isinstance(obj, collections.abc.Buffer) to test if obj implements the buffer protocol <bufferobjects> at runtime. For use in type annotations, either use ~collections.abc.Buffer or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).
  
  !ByteString was originally intended to be an abstract class that would serve as a supertype of both bytes and bytearray. However, since the ABC never had any methods, knowing that an object was an instance of !ByteString never actually told you anything useful about the object. Other common buffer types such as memoryview were also never understood as subtypes of !ByteString (either at runtime or by static type checkers).
  
  See PEP 688 <688#current-options> for more details. (Contributed by Shantanu Jain in 91896.)
tkinter:
- The !tkinter.Variable methods !trace_variable, !trace (an alias of !trace_variable), !trace_vdelete and !trace_vinfo, deprecated since Python 3.14, are scheduled for removal in Python 3.17. Use !trace_add, !trace_remove and !trace_info instead. (Contributed by Serhiy Storchaka in 120220.)

Pending removal in Python 3.19

builtins:
- Passing a complex number as the real or imag argument in the complex constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in 109218.)
ctypes:
- Implicitly switching to the MSVC-compatible struct layout by setting ~ctypes.Structure._pack_ but not ~ctypes.Structure._layout_ on non-Windows platforms.
hashlib:
- In hash function constructors such as ~hashlib.new or the direct hash-named constructors such as ~hashlib.md5 and ~hashlib.sha256, their optional initial data parameter could also be passed a keyword argument named data= or string= in various !hashlib implementations.
  
  Support for the string keyword argument name is now deprecated and slated for removal in Python 3.19.
  
  Before Python 3.13, the string keyword parameter was not correctly supported depending on the backend implementation of hash functions. Prefer passing the initial data as a positional argument for maximum backwards compatibility.
http.cookies:
- http.cookies.Morsel.js_output is deprecated and will be removed in Python 3.19.
- http.cookies.BaseCookie.js_output is deprecated and will be removed in Python 3.19.
imaplib:
- Altering IMAP4.file <imaplib.IMAP4.file> is now deprecated and slated for removal in Python 3.19. This property is now unused and changing its value does not automatically close the current file.
  
  Before Python 3.14, this property was used to implement the corresponding read() and readline() methods for ~imaplib.IMAP4 but this is no longer the case since then.
tkinter:
- tkinter.filedialog.askopenfiles has been deprecated since Python 3.16. Iterate over the names returned by ~tkinter.filedialog.askopenfilenames and open them one by one instead. (Contributed by Serhiy Storchaka in 152638.)

Pending removal in Python 3.20

Calling the __new__() method of struct.Struct without the format argument is deprecated and will be removed in Python 3.20. Calling ~object.__init__ method on initialized ~struct.Struct objects is deprecated and will be removed in Python 3.20.

(Contributed by Sergey B Kirpichev and Serhiy Storchaka in 143715.)
The __version__, version and VERSION attributes have been deprecated in these standard library modules and will be removed in Python 3.20. Use sys.version_info instead.
- argparse
- csv
- ctypes
- !ctypes.macholib
- decimal (use decimal.SPEC_VERSION instead)
- http.server
- imaplib
- ipaddress
- json
- logging (__date__ also deprecated)
- optparse
- pickle
- platform
- re
- socketserver
- tabnanny
- tarfile
- tkinter.font
- tkinter.ttk
- wsgiref.simple_server
- xml.etree.ElementTree
- !xml.sax.expatreader
- xml.sax.handler
- zlib
(Contributed by Hugo van Kemenade and Stan Ulbrych in 76007.)
The __author__, __credits__, __copyright__ and __date__ attributes have been deprecated in these standard library modules and will be removed in Python 3.20. Attribution is preserved in the source code and the version control history.
- bz2
- concurrent.futures
- inspect
- io
- json
- logging
- optparse
- platform
- pydoc
- tarfile
- tkinter.ttk
- tokenize
- uuid
(Contributed by Stan Ulbrych in 159240.)
Deprecations defined by 829:
- Warnings are produced for import lines found in {name}.pth files.
- {name}.pth files are no longer decoded in the locale encoding by default. They MUST be encoded in utf-8-sig.
(Contributed by Barry Warsaw in 148641.)
ast:
- Creating instances of abstract AST nodes (such as ast.AST or !ast.expr) is deprecated and will raise an error in Python 3.20.
typing:
- It is deprecated to call isinstance and issubclass checks on protocol classes that were not explicitly decorated with !runtime_checkable but that inherit from a runtime-checkable protocol class. This will raise a TypeError in Python 3.20.
  
  (Contributed by Bartosz Sławecki in 132604.)

Pending removal in Python 3.21

abc
- Soft-deprecated since Python 3.3 abc.abstractclassmethod, abc.abstractstaticmethod, and abc.abstractproperty now raise a DeprecationWarning. These classes will be removed in Python 3.21, instead use abc.abstractmethod with classmethod, staticmethod, and property respectively.
ast:
- Classes slice, Index, ExtSlice, Suite, Param, AugLoad and AugStore, will be removed in Python 3.21. These types are not generated by the parser or accepted by the code generator.
- The dims property of ast.Tuple will be removed in Python 3.21. Use the ast.Tuple.elts property instead.
functools:
- Using a return annotation to infer the dispatch type for functools.singledispatch or functools.singledispatchmethod is deprecated since Python 3.16 and will raise TypeError in Python 3.21. Annotate the dispatch parameter or pass the dispatch type explicitly instead. (Contributed by Bartosz Sławecki in 143465.)
struct:
- Soft-deprecated since Python 3.15, using 'F' and 'D' type codes are now deprecated. These codes will be removed in Python 3.21. Use instead two-letter forms 'Zf' and 'Zd'.
tempfile:
- tempfile._TemporaryFileWrapper will be removed in Python 3.21. Use the public tempfile.TemporaryFileWrapper instead.

Pending removal in future versions

The following APIs will be removed in the future, although there is currently no date scheduled for their removal.

argparse:
- Nesting argument groups and nesting mutually exclusive groups are deprecated.
- Passing the undocumented keyword argument prefix_chars to ~argparse.ArgumentParser.add_argument_group is now deprecated.
- The argparse.FileType type converter is deprecated.
builtins:
- Generators: throw(type, exc, tb) and athrow(type, exc, tb) signature is deprecated: use throw(exc) and athrow(exc) instead, the single argument signature.
- Currently Python accepts numeric literals immediately followed by keywords, for example 0in x, 1or x, 0if 1else 2. It allows confusing and ambiguous expressions like [0x1for x in y] (which can be interpreted as [0x1 for x in y] or [0x1f or x in y]). A syntax warning is raised if the numeric literal is immediately followed by one of keywords and, else, for, if, in, is and or. In a future release it will be changed to a syntax error. (87999)
- Support for __index__() and __int__() method returning non-int type: these methods will be required to return an instance of a strict subclass of int.
- Support for __float__() method returning a strict subclass of float: these methods will be required to return an instance of float.
- Support for __complex__() method returning a strict subclass of complex: these methods will be required to return an instance of complex.
calendar: calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY. (Contributed by Prince Roshan in 103636.)
codecs: use open instead of codecs.open. (133038)
!codeobject.co_lnotab: use the codeobject.co_lines method instead.
datetime:
- ~datetime.datetime.utcnow: use datetime.datetime.now(tz=datetime.UTC).
- ~datetime.datetime.utcfromtimestamp: use datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC).
gettext: Plural value must be an integer.
importlib:
- ~importlib.util.cache_from_source debug_override parameter is deprecated: use the optimization parameter instead.
importlib.metadata:
- EntryPoints tuple interface.
- Implicit None on return values.
logging: the warn() method has been deprecated since Python 3.3, use ~logging.warning instead.
mailbox: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.
os: Calling os.register_at_fork in a multi-threaded process.
os.path: os.path.commonprefix is deprecated, use os.path.commonpath for path prefixes. The os.path.commonprefix function is being deprecated due to having a misleading name and module. The function is not safe to use for path prefixes despite being included in a module about path manipulation, meaning it is easy to accidentally introduce path traversal vulnerabilities into Python programs by using this function.
!pydoc.ErrorDuringImport: A tuple value for exc_info parameter is deprecated, use an exception instance.
re: 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 91760.)
shutil: ~shutil.rmtree's onerror parameter is deprecated in Python 3.12; use the onexc parameter instead.
ssl options and protocols:
- ssl.SSLContext without protocol argument is deprecated.
- ssl.SSLContext: ~ssl.SSLContext.set_npn_protocols and !selected_npn_protocol are deprecated: use ALPN instead.
- ssl.OP_NO_SSL* options
- ssl.OP_NO_TLS* options
- ssl.PROTOCOL_SSLv3
- ssl.PROTOCOL_TLS
- ssl.PROTOCOL_TLSv1
- ssl.PROTOCOL_TLSv1_1
- ssl.PROTOCOL_TLSv1_2
- ssl.TLSVersion.SSLv3
- ssl.TLSVersion.TLSv1
- ssl.TLSVersion.TLSv1_1
threading methods:
- !threading.Condition.notifyAll: use ~threading.Condition.notify_all.
- !threading.Event.isSet: use ~threading.Event.is_set.
- !threading.Thread.isDaemon, threading.Thread.setDaemon: use threading.Thread.daemon attribute.
- !threading.Thread.getName, threading.Thread.setName: use threading.Thread.name attribute.
- !threading.currentThread: use threading.current_thread.
- !threading.activeCount: use threading.active_count.
typing.Text (92332).
The internal class typing._UnionGenericAlias is no longer used to implement typing.Union. To preserve compatibility with users using this private class, a compatibility shim will be provided until at least Python 3.17. (Contributed by Jelle Zijlstra in 105499.)
unittest.IsolatedAsyncioTestCase: it is deprecated to return a value that is not None from a test case.
urllib.parse deprecated functions: ~urllib.parse.urlparse instead
- splitattr()
- splithost()
- splitnport()
- splitpasswd()
- splitport()
- splitquery()
- splittag()
- splittype()
- splituser()
- splitvalue()
- to_bytes()
wsgiref: SimpleHandler.stdout.write() should not do partial writes.
xml.etree.ElementTree: Testing the truth value of an ~xml.etree.ElementTree.Element is deprecated. In a future release it will always return True. Prefer explicit len(elem) or elem is not None tests instead.
sys._clear_type_cache is deprecated: use sys._clear_internal_caches instead.

Removed

asynchat and asyncore

These two modules have been removed according to the schedule in 594, having been deprecated in Python 3.6. Use asyncio instead. (Contributed by Nikita Sobolev in 96580.)

configparser

Several names deprecated in the configparser way back in 3.2 have been removed per 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 ~configparser.ConfigParser name instead.
- configparser.ConfigParser no longer has a readfp method. Use ~configparser.ConfigParser.read_file instead.

distutils

Remove the !distutils package. It was deprecated in Python 3.10 by 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 92584.)

ensurepip

Remove the bundled setuptools wheel from ensurepip, and stop installing setuptools in environments created by 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 95299.)

enum

Remove enum's EnumMeta.__getattr__, which is no longer needed for enum attribute access. (Contributed by Ethan Furman in 95083.)

ftplib

Remove ftplib's FTP_TLS.ssl_version class attribute: use the context parameter instead. (Contributed by Victor Stinner in 94172.)

gzip

Remove the filename attribute of gzip's gzip.GzipFile, deprecated since Python 2.6, use the ~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 94196.)

hashlib

Remove the pure Python implementation of hashlib's hashlib.pbkdf2_hmac, deprecated in Python 3.10. Python 3.10 and newer requires OpenSSL 1.1.1 (644): this OpenSSL version provides a C implementation of ~hashlib.pbkdf2_hmac which is faster. (Contributed by Victor Stinner in 94199.)

importlib

Many previously deprecated cleanups in importlib have now been completed:
- References to, and support for !module_repr has been removed. (Contributed by Barry Warsaw in 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 65961 and 97850.)
- Support for find_loader() and find_module() APIs have been removed. (Contributed by Barry Warsaw in 98040.)
- importlib.abc.Finder, pkgutil.ImpImporter, and pkgutil.ImpLoader have been removed. (Contributed by Barry Warsaw in 98040.)

imp

The !imp module has been removed. (Contributed by Barry Warsaw in 98040.)

To migrate, consult the following correspondence table:

imp importlib

imp.NullImporter Insert None into sys.path_importer_cache

imp.cache_from_source() importlib.util.cache_from_source

imp.find_module() importlib.util.find_spec

imp.get_magic() importlib.util.MAGIC_NUMBER

imp.get_suffixes() importlib.machinery.SOURCE_SUFFIXES, importlib.machinery.EXTENSION_SUFFIXES, and importlib.machinery.BYTECODE_SUFFIXES

imp.get_tag() sys.implementation.cache_tag <sys.implementation>

imp.load_module() importlib.import_module

imp.new_module(name) types.ModuleType(name)

imp.reload() importlib.reload

imp.source_from_cache() importlib.util.source_from_cache

imp.load_source() See below

imp	importlib
`imp.NullImporter`	Insert `None` into `sys.path_importer_cache`
`imp.cache_from_source()`	`importlib.util.cache_from_source`
`imp.find_module()`	`importlib.util.find_spec`
`imp.get_magic()`	`importlib.util.MAGIC_NUMBER`
`imp.get_suffixes()`	`importlib.machinery.SOURCE_SUFFIXES`, `importlib.machinery.EXTENSION_SUFFIXES`, and `importlib.machinery.BYTECODE_SUFFIXES`
`imp.get_tag()`	`sys.implementation.cache_tag <sys.implementation>`
`imp.load_module()`	`importlib.import_module`
`imp.new_module(name)`	`types.ModuleType(name)`
`imp.reload()`	`importlib.reload`
`imp.source_from_cache()`	`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 !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

Remove io's io.OpenWrapper and _pyio.OpenWrapper, deprecated in Python 3.10: just use open instead. The open (io.open) function is a built-in function. Since Python 3.10, !_pyio.open is also a static method. (Contributed by Victor Stinner in 94169.)

locale

Remove locale's !locale.format function, deprecated in Python 3.7: use locale.format_string instead. (Contributed by Victor Stinner in 94226.)

smtpd

The smtpd module has been removed according to the schedule in 594, having been deprecated in Python 3.4.7 and 3.5.4. Use the aiosmtpd PyPI module or any other asyncio-based server instead. (Contributed by Oleg Iarygin in 93243.)

sqlite3

The following undocumented sqlite3 features, deprecated in Python 3.10, are now removed:
- sqlite3.enable_shared_cache()
- sqlite3.OptimizedUnicode
If 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 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 92548.)

ssl

Remove ssl's !ssl.RAND_pseudo_bytes function, deprecated in Python 3.6: use os.urandom or ssl.RAND_bytes instead. (Contributed by Victor Stinner in 94199.)
Remove the !ssl.match_hostname function. It was deprecated in Python 3.7. OpenSSL performs hostname matching since Python 3.7, Python no longer uses the !ssl.match_hostname function. (Contributed by Victor Stinner in 94199.)
Remove the !ssl.wrap_socket function, deprecated in Python 3.7: instead, create a ssl.SSLContext object and call its ssl.SSLContext.wrap_socket method. Any package that still uses !ssl.wrap_socket is broken and insecure. The function neither sends a SNI TLS extension nor validates the server hostname. Code is subject to 295 (Improper Certificate Validation). (Contributed by Victor Stinner in 94199.)

unittest

Remove many long-deprecated unittest features:

A number of ~unittest.TestCase method aliases:

Deprecated alias	Method Name	Deprecated in
`failUnless`	`.assertTrue`	3.1
`failIf`	`.assertFalse`	3.1
`failUnlessEqual`	`.assertEqual`	3.1
`failIfEqual`	`.assertNotEqual`	3.1
`failUnlessAlmostEqual`	`.assertAlmostEqual`	3.1
`failIfAlmostEqual`	`.assertNotAlmostEqual`	3.1
`failUnlessRaises`	`.assertRaises`	3.1
`assert_`	`.assertTrue`	3.2
`assertEquals`	`.assertEqual`	3.2
`assertNotEquals`	`.assertNotEqual`	3.2
`assertAlmostEquals`	`.assertAlmostEqual`	3.2
`assertNotAlmostEquals`	`.assertNotAlmostEqual`	3.2
`assertRegexpMatches`	`.assertRegex`	3.2
`assertRaisesRegexp`	`.assertRaisesRegex`	3.2
`assertNotRegexpMatches`	`.assertNotRegex`	3.5

You can use https://github.com/isidentical/teyit to automatically modernise your unit tests.

Undocumented and broken ~unittest.TestCase method assertDictContainsSubset (deprecated in Python 3.2).
Undocumented TestLoader.loadTestsFromModule <unittest.TestLoader.loadTestsFromModule> parameter use_load_tests (deprecated and ignored since Python 3.5).
An alias of the ~unittest.TextTestResult class: _TextTestResult (deprecated in Python 3.2).

(Contributed by Serhiy Storchaka in 89325.)

webbrowser

Remove support for obsolete browsers from webbrowser. The removed browsers include: Grail, Mosaic, Netscape, Galeon, Skipstone, Iceape, Firebird, and Firefox versions 35 and below (102871).

xml.etree.ElementTree

Remove the ElementTree.Element.copy() method of the pure Python implementation, deprecated in Python 3.10, use the copy.copy function instead. The C implementation of xml.etree.ElementTree has no copy() method, only a __copy__() method. (Contributed by Victor Stinner in 94383.)

zipimport

Remove zipimport's find_loader() and find_module() methods, deprecated in Python 3.10: use the find_spec() method instead. See 451 for the rationale. (Contributed by Victor Stinner in 94379.)

Others

Remove the suspicious rule from the documentation Makefile and Doc/tools/rstlint.py, both in favor of sphinx-lint. (Contributed by Julien Palard in 98179.)
Remove the keyfile and certfile parameters from the ftplib, imaplib, poplib and smtplib modules, and the key_file, cert_file and check_hostname parameters from the http.client module, all deprecated since Python 3.6. Use the context parameter (ssl_context in imaplib) instead. (Contributed by Victor Stinner in 94172.)
Remove Jython compatibility hacks from several stdlib modules and tests. (Contributed by Nikita Sobolev in 99482.)
Remove _use_broken_old_ctypes_structure_semantics_ flag from ctypes module. (Contributed by Nikita Sobolev in 99285.)

Porting to Python 3.12

This section lists previously described changes and other bugfixes that may require changes to your code.

Changes in the Python API

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 91760.)
Remove randrange() functionality deprecated since Python 3.10. Formerly, randrange(10.0) losslessly converted to randrange(10). Now, it raises a TypeError. Also, the exception raised for non-integer values such as randrange(10.5) or randrange('10') has been changed from ValueError to TypeError. This also prevents bugs where randrange(1e25) would silently select from a larger range than randrange(10**25). (Originally suggested by Serhiy Storchaka 86388.)
argparse.ArgumentParser changed encoding and error handler for reading arguments from file (e.g. fromfile_prefix_chars option) from default text encoding (e.g. locale.getpreferredencoding(False) <locale.getpreferredencoding>) to 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 asyncio-based aiosmtpd PyPI module.
shlex.split: Passing None for s argument now raises an exception, rather than reading sys.stdin. The feature was deprecated in Python 3.9. (Contributed by Victor Stinner in 94352.)
The os module no longer accepts bytes-like paths, like bytearray and memoryview types: only the exact bytes type is accepted for bytes strings. (Contributed by Victor Stinner in 98393.)
syslog.openlog and syslog.closelog now fail if used in subinterpreters. syslog.syslog may still be used in subinterpreters, but now only if 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, syslog is a wrapper around process-global resources, which are best managed from the main interpreter. (Contributed by Donghee Na in 99127.)
The undocumented locking behavior of ~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.
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 103176.)
When extracting tar files using tarfile or shutil.unpack_archive, pass the filter argument to limit features that may be surprising or dangerous. See tarfile-extraction-filter for details.
The output of the tokenize.tokenize and tokenize.generate_tokens functions is now changed due to the changes introduced in 701. This means that STRING tokens are not emitted any more for f-strings and the tokens described in 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 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 tokenize.TokenError as incomplete multiline strings do.
- Some incomplete or invalid Python code now raises 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 TabError.
The threading module now expects the !_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 112826.)

Build Changes

Python no longer uses setup.py to build shared C extension modules. Build parameters like headers and libraries are detected in configure script. Extensions are built by Makefile. Most extensions use pkg-config and fall back to manual detection. (Contributed by Christian Heimes in 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 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 89536.)
Add COMPILEALL_OPTS variable in Makefile to override 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 99289.)
Add platform triplets for 64-bit LoongArch:
- loongarch64-linux-gnusf
- loongarch64-linux-gnuf32
- loongarch64-linux-gnu
(Contributed by Zhang Na in 90656.)
PYTHON_FOR_REGEN now require Python 3.10 or newer.
Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate configure. (Contributed by Christian Heimes in 89886.)
Windows builds and macOS installers from python.org now use OpenSSL 3.0.

C API Changes

New Features

697: Introduce the 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 (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 101101.)
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 PyType_GetTypeDataSize added to allow access to subclass-specific instance data.
- Py_TPFLAGS_ITEMS_AT_END and PyObject_GetItemData added to allow safely extending certain variable-sized types, including PyType_Type.
- Py_RELATIVE_OFFSET added to allow defining members <PyMemberDef> in terms of a subclass-specific struct.
(Contributed by Petr Viktorin in 103509.)
Add the new limited C API <limited-c-api> function PyType_FromMetaclass, which generalizes the existing PyType_FromModuleAndSpec using an additional metaclass argument. (Contributed by Wenzel Jakob in 93012.)
API for creating objects that can be called using the vectorcall protocol <vectorcall> was added to the Limited API <stable>:
- Py_TPFLAGS_HAVE_VECTORCALL
- PyVectorcall_NARGS
- PyVectorcall_Call
- vectorcallfunc
The Py_TPFLAGS_HAVE_VECTORCALL flag is now removed from a class when the class's ~object.__call__ method is reassigned. This makes vectorcall safe to use with mutable types (i.e. heap types without the immutable flag, Py_TPFLAGS_IMMUTABLETYPE). Mutable types that do not override ~PyTypeObject.tp_call now inherit the Py_TPFLAGS_HAVE_VECTORCALL flag. (Contributed by Petr Viktorin in 93274.)

The Py_TPFLAGS_MANAGED_DICT and Py_TPFLAGS_MANAGED_WEAKREF flags have been added. This allows extensions classes to support object ~object.__dict__ and weakrefs with less bookkeeping, using less memory and with faster access.
API for performing calls using the vectorcall protocol <vectorcall> was added to the Limited API <stable>:
- PyObject_Vectorcall
- PyObject_VectorcallMethod
- PY_VECTORCALL_ARGUMENTS_OFFSET
This means that both the incoming and outgoing ends of the vector call protocol are now available in the Limited API <stable>. (Contributed by Wenzel Jakob in 98586.)
Add two new public functions, PyEval_SetProfileAllThreads and 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 93503.)
Add new function PyFunction_SetVectorcall to the C API which sets the vectorcall field of a given PyFunctionObject. (Contributed by Andrew Frost in 92257.)
The C API now permits registering callbacks via PyDict_AddWatcher, 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 91052.)
Add PyType_AddWatcher and PyType_Watch API to register callbacks to receive notification on changes to a type. (Contributed by Carl Meyer in 91051.)
Add PyCode_AddWatcher and PyCode_ClearWatcher APIs to register callbacks to receive notification on creation and destruction of code objects. (Contributed by Itamar Oren in 91054.)
Add PyFrame_GetVar and PyFrame_GetVarString functions to get a frame variable by its name. (Contributed by Victor Stinner in 91248.)
Add PyErr_GetRaisedException and 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 PyErr_Fetch and PyErr_Restore. This is less error prone and a bit more efficient. (Contributed by Mark Shannon in 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 101578.)
Add PyException_GetArgs and PyException_SetArgs as convenience functions for retrieving and modifying the ~BaseException.args passed to the exception's constructor. (Contributed by Mark Shannon in 101578.)
Add PyErr_DisplayException, which takes an exception instance, to replace the legacy-api !PyErr_Display. (Contributed by Irit Katriel in 102755).

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 static
- sys.getunicodeinternedsize This returns the total number of unicode objects that have been interned. This is now needed for refleak.py to correctly track reference counts and allocated blocks
(Contributed by Eddie Elizondo in 84436.)
684: Add the new Py_NewInterpreterFromConfig function and PyInterpreterConfig, which may be used to create sub-interpreters with their own GILs. (See whatsnew312-pep684 for more info.) (Contributed by Eric Snow in 104110.)
In the limited C API version 3.12, Py_INCREF and Py_DECREF functions are now implemented as opaque function calls to hide implementation details. (Contributed by Victor Stinner in 105387.)

Porting to Python 3.12

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 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 PyTypeObject.tp_subclasses may now not be a valid object pointer. Its type was changed to 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 ~type.__subclasses__ (using PyObject_CallMethod, for example).
Add support of more formatting options (left aligning, octals, uppercase hexadecimals, intmax_t, ptrdiff_t, wchar_t C strings, variable width and precision) in PyUnicode_FromFormat and PyUnicode_FromFormatV. (Contributed by Serhiy Storchaka in 98836.)
An unrecognized format character in PyUnicode_FromFormat and PyUnicode_FromFormatV now sets a 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 95781.)
Fix wrong sign placement in PyUnicode_FromFormat and PyUnicode_FromFormatV. (Contributed by Philip Georgi in 95504.)
Extension classes wanting to add a ~object.__dict__ or weak reference slot should use Py_TPFLAGS_MANAGED_DICT and 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 (95589), and performance may be worse. Classes declaring Py_TPFLAGS_MANAGED_DICT must call !_PyObject_VisitManagedDict and !_PyObject_ClearManagedDict to traverse and clear their instance's dictionaries. To clear weakrefs, call PyObject_ClearWeakRefs, as before.
The PyUnicode_FSDecoder function no longer accepts bytes-like paths, like bytearray and memoryview types: only the exact bytes type is accepted for bytes strings. (Contributed by Victor Stinner in 98393.)
The Py_CLEAR, Py_SETREF and 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 98724.)
The interpreter's error indicator is now always normalized. This means that PyErr_SetObject, PyErr_SetString and the other functions that set the error indicator now normalize the exception before storing it. (Contributed by Mark Shannon in 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_FromSpec
- PyType_FromSpecWithBases
- PyType_FromModuleAndSpec
Creating classes whose metaclass overrides ~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 PyType_FromMetaclass (added in Python 3.12) already disallows creating classes whose metaclass overrides tp_new (~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:
  - If initialization can be skipped, it can be done in ~PyTypeObject.tp_init instead.
  - If the metaclass doesn't need to be instantiated from Python, set its tp_new to NULL using the 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 calling <call> the metaclass.
- If you know the tp_new can be skipped safely, filter the deprecation warning out using warnings.catch_warnings from Python.
PyOS_InputHook and PyOS_ReadlineFunctionPointer are no longer called in 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 104668 for more info.
PyLongObject has had its internals changed for better performance. Although the internals of 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 PyLongObjects which fit into a single machine word:
- PyUnstable_Long_IsCompact
- PyUnstable_Long_CompactValue
Custom allocators, set via 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.

Deprecated

In accordance with 699, the ma_version_tag field in 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 101193. PEP by Ken Jin.)
Deprecate global configuration variable:
- !Py_DebugFlag: use PyConfig.parser_debug
- !Py_VerboseFlag: use PyConfig.verbose
- !Py_QuietFlag: use PyConfig.quiet
- !Py_InteractiveFlag: use PyConfig.interactive
- !Py_InspectFlag: use PyConfig.inspect
- !Py_OptimizeFlag: use PyConfig.optimization_level
- !Py_NoSiteFlag: use PyConfig.site_import
- !Py_BytesWarningFlag: use PyConfig.bytes_warning
- !Py_FrozenFlag: use PyConfig.pathconfig_warnings
- !Py_IgnoreEnvironmentFlag: use PyConfig.use_environment
- !Py_DontWriteBytecodeFlag: use PyConfig.write_bytecode
- !Py_NoUserSiteDirectory: use PyConfig.user_site_directory
- !Py_UnbufferedStdioFlag: use PyConfig.buffered_stdio
- !Py_HashRandomizationFlag: use PyConfig.use_hash_seed and PyConfig.hash_seed
- !Py_IsolatedFlag: use PyConfig.isolated
- !Py_LegacyWindowsFSEncodingFlag: use PyPreConfig.legacy_windows_fs_encoding
- !Py_LegacyWindowsStdioFlag: use PyConfig.legacy_windows_stdio
- !Py_FileSystemDefaultEncoding: use PyConfig.filesystem_encoding
- !Py_HasFileSystemDefaultEncoding: use PyConfig.filesystem_encoding
- !Py_FileSystemDefaultEncodeErrors: use PyConfig.filesystem_errors
- !Py_UTF8Mode: use PyPreConfig.utf8_mode (see Py_PreInitialize)
The Py_InitializeFromConfig API should be used with PyConfig instead. (Contributed by Victor Stinner in 77782.)
Creating immutable types <Py_TPFLAGS_IMMUTABLETYPE> with mutable bases is deprecated and will be disabled in Python 3.14. (95388)
The 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 Python.h, with a Py prefix added if it was missing:
- PyMemberDef, PyMember_GetOne and PyMember_SetOne
- Type macros like Py_T_INT, Py_T_DOUBLE, etc. (previously T_INT, T_DOUBLE, etc.)
- The flags Py_READONLY (previously READONLY) and Py_AUDIT_READ (previously all uppercase)
Several items are not exposed from Python.h:
- T_OBJECT (use Py_T_OBJECT_EX)
- T_NONE (previously undocumented, and pretty quirky)
- The macro WRITE_RESTRICTED which does nothing.
- The macros RESTRICTED and READ_RESTRICTED, equivalents of Py_AUDIT_READ.
- In some configurations, <stddef.h> is not included from 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 47146 by Petr Viktorin, based on earlier work by Alexander Belopolsky and Matthias Braun.)
PyErr_Fetch and PyErr_Restore are deprecated. Use PyErr_GetRaisedException and PyErr_SetRaisedException instead. (Contributed by Mark Shannon in 101578.)
!PyErr_Display is deprecated. Use PyErr_DisplayException instead. (Contributed by Irit Katriel in 102755).
_PyErr_ChainExceptions is deprecated. Use _PyErr_ChainExceptions1 instead. (Contributed by Irit Katriel in 102192.)
Using PyType_FromSpec, PyType_FromSpecWithBases or PyType_FromModuleAndSpec to create a class whose metaclass overrides ~PyTypeObject.tp_new is deprecated. Call the metaclass instead.

Pending removal in Python 3.14

The ma_version_tag field in PyDictObject for extension modules (699; 101193).
Creating immutable types <Py_TPFLAGS_IMMUTABLETYPE> with mutable bases (95388).

Pending removal in Python 3.15

The !PyImport_ImportModuleNoBlock: Use PyImport_ImportModule instead.
!PyWeakref_GetObject and !PyWeakref_GET_OBJECT: Use PyWeakref_GetRef instead. The pythoncapi-compat project can be used to get PyWeakref_GetRef on Python 3.12 and older.
!PyUnicode_AsDecodedObject: Use PyCodec_Decode instead.
!PyUnicode_AsDecodedUnicode: Use PyCodec_Decode instead; Note that some codecs (for example, "base64") may return a type other than str, such as bytes.
!PyUnicode_AsEncodedObject: Use PyCodec_Encode instead.
!PyUnicode_AsEncodedUnicode: Use PyCodec_Encode instead; Note that some codecs (for example, "base64") may return a type other than bytes, such as str.
Python initialization functions, deprecated in Python 3.13:
- !Py_GetPath: Use PyConfig_Get("module_search_paths") <PyConfig_Get> (sys.path) instead.
- !Py_GetPrefix: Use PyConfig_Get("base_prefix") <PyConfig_Get> (sys.base_prefix) instead. Use PyConfig_Get("prefix") <PyConfig_Get> (sys.prefix) if virtual environments <venv-def> need to be handled.
- !Py_GetExecPrefix: Use PyConfig_Get("base_exec_prefix") <PyConfig_Get> (sys.base_exec_prefix) instead. Use PyConfig_Get("exec_prefix") <PyConfig_Get> (sys.exec_prefix) if virtual environments <venv-def> need to be handled.
- !Py_GetProgramFullPath: Use PyConfig_Get("executable") <PyConfig_Get> (sys.executable) instead.
- !Py_GetProgramName: Use PyConfig_Get("executable") <PyConfig_Get> (sys.executable) instead.
- !Py_GetPythonHome: Use PyConfig_Get("home") <PyConfig_Get> or the PYTHONHOME environment variable instead.
The pythoncapi-compat project can be used to get PyConfig_Get on Python 3.13 and older.

Pending removal in Python 3.16

Functions to configure Python's initialization, deprecated in Python 3.11:
- !PySys_SetArgvEx(): Set PyConfig.argv instead.
- !PySys_SetArgv(): Set PyConfig.argv instead.
- !Py_SetProgramName(): Set PyConfig.program_name instead.
- !Py_SetPythonHome(): Set PyConfig.home instead.
The Py_InitializeFromConfig API should be used with PyConfig instead.
Global configuration variables:
- !Py_DebugFlag: Use PyConfig.parser_debug or PyConfig_Get("parser_debug") <PyConfig_Get> instead.
- !Py_VerboseFlag: Use PyConfig.verbose or PyConfig_Get("verbose") <PyConfig_Get> instead.
- !Py_QuietFlag: Use PyConfig.quiet or PyConfig_Get("quiet") <PyConfig_Get> instead.
- !Py_InteractiveFlag: Use PyConfig.interactive or PyConfig_Get("interactive") <PyConfig_Get> instead.
- !Py_InspectFlag: Use PyConfig.inspect or PyConfig_Get("inspect") <PyConfig_Get> instead.
- !Py_OptimizeFlag: Use PyConfig.optimization_level or PyConfig_Get("optimization_level") <PyConfig_Get> instead.
- !Py_NoSiteFlag: Use PyConfig.site_import or PyConfig_Get("site_import") <PyConfig_Get> instead.
- !Py_BytesWarningFlag: Use PyConfig.bytes_warning or PyConfig_Get("bytes_warning") <PyConfig_Get> instead.
- !Py_FrozenFlag: Use PyConfig.pathconfig_warnings or PyConfig_Get("pathconfig_warnings") <PyConfig_Get> instead.
- !Py_IgnoreEnvironmentFlag: Use PyConfig.use_environment or PyConfig_Get("use_environment") <PyConfig_Get> instead.
- !Py_DontWriteBytecodeFlag: Use PyConfig.write_bytecode or PyConfig_Get("write_bytecode") <PyConfig_Get> instead.
- !Py_NoUserSiteDirectory: Use PyConfig.user_site_directory or PyConfig_Get("user_site_directory") <PyConfig_Get> instead.
- !Py_UnbufferedStdioFlag: Use PyConfig.buffered_stdio or PyConfig_Get("buffered_stdio") <PyConfig_Get> instead.
- !Py_HashRandomizationFlag: Use PyConfig.use_hash_seed and PyConfig.hash_seed or PyConfig_Get("hash_seed") <PyConfig_Get> instead.
- !Py_IsolatedFlag: Use PyConfig.isolated or PyConfig_Get("isolated") <PyConfig_Get> instead.
- !Py_LegacyWindowsFSEncodingFlag: Use PyPreConfig.legacy_windows_fs_encoding or PyConfig_Get("legacy_windows_fs_encoding") <PyConfig_Get> instead.
- !Py_LegacyWindowsStdioFlag: Use PyConfig.legacy_windows_stdio or PyConfig_Get("legacy_windows_stdio") <PyConfig_Get> instead.
- !Py_FileSystemDefaultEncoding, !Py_HasFileSystemDefaultEncoding: Use PyConfig.filesystem_encoding or PyConfig_Get("filesystem_encoding") <PyConfig_Get> instead.
- !Py_FileSystemDefaultEncodeErrors: Use PyConfig.filesystem_errors or PyConfig_Get("filesystem_errors") <PyConfig_Get> instead.
- !Py_UTF8Mode: Use PyPreConfig.utf8_mode or PyConfig_Get("utf8_mode") <PyConfig_Get> instead. (see Py_PreInitialize)
The Py_InitializeFromConfig API should be used with PyConfig to set these options. Or PyConfig_Get can be used to get these options at runtime.
Py_UNICODE which was deprecated by 393.

Pending removal in future versions

The following APIs are deprecated and will be removed, although there is currently no date scheduled for their removal.

Py_TPFLAGS_HAVE_FINALIZE: Unneeded since Python 3.8.
PyErr_Fetch: Use PyErr_GetRaisedException instead.
PyErr_NormalizeException: Use PyErr_GetRaisedException instead.
PyErr_Restore: Use PyErr_SetRaisedException instead.
PyOS_AfterFork: Use PyOS_AfterFork_Child instead.
PySlice_GetIndicesEx: Use PySlice_Unpack and PySlice_AdjustIndices instead.
PyUnicode_READY: Unneeded since Python 3.12
!PyErr_Display: Use PyErr_DisplayException instead.
!_PyErr_ChainExceptions: Use !_PyErr_ChainExceptions1 instead.
!PyBytesObject.ob_shash member: call PyObject_Hash instead.
Thread Local Storage (TLS) API:
- PyThread_create_key: Use PyThread_tss_alloc instead.
- PyThread_delete_key: Use PyThread_tss_free instead.
- PyThread_set_key_value: Use PyThread_tss_set instead.
- PyThread_get_key_value: Use PyThread_tss_get instead.
- PyThread_delete_key_value: Use PyThread_tss_delete instead.
- PyThread_ReInitTLS: Unneeded since Python 3.7.

Removed

Remove the token.h header file. There was never any public tokenizer C API. The token.h header file was only designed to be used by Python internals. (Contributed by Victor Stinner in 92651.)
Legacy Unicode APIs have been removed. See 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_SIZE
Remove the PyUnicode_InternImmortal() function macro. (Contributed by Victor Stinner in 85858.)

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