What’s New In Python 3.13

What’s New In Python 3.13¶
- Editors:
Adam Turner and Thomas Wouters
This article explains the new features in Python 3.13, compared to 3.12. Python 3.13 was released on October 7, 2024. For full details, see the changelog.
See also
PEP 719 – Python 3.13 Release Schedule
Summary – Release Highlights¶
Python 3.13 is a stable release of the Python programming language, with a mix of changes to the language, the implementation and the standard library. The biggest changes include a new interactive interpreter, experimental support for running in a free-threaded mode (PEP 703), and a Just-In-Time compiler (PEP 744).
Error messages continue to improve, with tracebacks now highlighted in color
by default. The locals()
builtin now has defined semantics for changing the returned mapping,
and type parameters now support default values.
The library changes contain removal of deprecated APIs and modules, as well as the usual improvements in user-friendliness and correctness. Several legacy standard library modules have now been removed following their deprecation in Python 3.11 (PEP 594).
This article doesn’t attempt to provide a complete specification of all new features, but instead gives a convenient overview. For full details refer to the documentation, such as the Library Reference and Language Reference. 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. See Porting to Python 3.13 for guidance on upgrading from earlier versions of Python.
Interpreter improvements:
A greatly improved interactive interpreter and improved error messages.
PEP 667: The
locals()
builtin now has defined semantics when mutating the returned mapping. Python debuggers and similar tools may now more reliably update local variables in optimized scopes even during concurrent code execution.PEP 703: CPython 3.13 has experimental support for running with the global interpreter lock disabled. See Free-threaded CPython for more details.
PEP 744: A basic JIT compiler was added. It is currently disabled by default (though we may turn it on later). Performance improvements are modest – we expect to improve this over the next few releases.
Color support in the new interactive interpreter, as well as in tracebacks and doctest output. This can be disabled through the
PYTHON_COLORS
andNO_COLOR
environment variables.
Python data model improvements:
__static_attributes__
stores the names of attributes accessed throughself.X
in any function in a class body.__firstlineno__
records the first line number of a class definition.
Significant improvements in the standard library:
Add a new
PythonFinalizationError
exception, raised when an operation is blocked during finalization.The
argparse
module now supports deprecating command-line options, positional arguments, and subcommands.The new functions
base64.z85encode()
andbase64.z85decode()
support encoding and decoding Z85 data.The
copy
module now has acopy.replace()
function, with support for many builtin types and any class defining the__replace__()
method.The new
dbm.sqlite3
module is now the defaultdbm
backend.The
os
module has a suite of new functions for working with Linux’s timer notification file descriptors.The
random
module now has a command-line interface.
Security improvements:
ssl.create_default_context()
setsssl.VERIFY_X509_PARTIAL_CHAIN
andssl.VERIFY_X509_STRICT
as default flags.
C API improvements:
The
Py_mod_gil
slot is now used to indicate that an extension module supports running with the GIL disabled.The PyTime C API has been added, providing access to system clocks.
PyMutex
is a new lightweight mutex that occupies a single byte.There is a new suite of functions for generating PEP 669 monitoring events in the C API.
New typing features:
PEP 696: Type parameters (
typing.TypeVar
,typing.ParamSpec
, andtyping.TypeVarTuple
) now support defaults.PEP 702: The new
warnings.deprecated()
decorator adds support for marking deprecations in the type system and at runtime.PEP 705:
typing.ReadOnly
can be used to mark an item of atyping.TypedDict
as read-only for type checkers.PEP 742:
typing.TypeIs
provides more intuitive type narrowing behavior, as an alternative totyping.TypeGuard
.
Platform support:
PEP 730: Apple’s iOS is now an officially supported platform, at tier 3.
PEP 738: Android is now an officially supported platform, at tier 3.
wasm32-wasi
is now supported as a tier 2 platform.wasm32-emscripten
is no longer an officially supported platform.
Important removals:
PEP 594: The remaining 19 “dead batteries” (legacy stdlib modules) have been removed from the standard library:
aifc
,audioop
,cgi
,cgitb
,chunk
,crypt
,imghdr
,mailcap
,msilib
,nis
,nntplib
,ossaudiodev
,pipes
,sndhdr
,spwd
,sunau
,telnetlib
,uu
andxdrlib
.Remove the 2to3 tool and
lib2to3
module (deprecated in Python 3.11).Remove the
tkinter.tix
module (deprecated in Python 3.6).Remove the
locale.resetlocale()
function.Remove the
typing.io
andtyping.re
namespaces.Remove chained
classmethod
descriptors.
Release schedule changes:
PEP 602 (“Annual Release Cycle for Python”) has been updated to extend the full support (‘bugfix’) period for new releases to two years. This updated policy means that:
Python 3.9–3.12 have one and a half years of full support, followed by three and a half years of security fixes.
Python 3.13 and later have two years of full support, followed by three years of security fixes.
New Features¶
A better interactive interpreter¶
Python now uses a new interactive shell by default, based on code from the PyPy project. When the user starts the REPL from an interactive terminal, the following new features are now supported:
Multiline editing with history preservation.
Direct support for REPL-specific commands like help, exit, and quit, without the need to call them as functions.
Prompts and tracebacks with color enabled by default.
Interactive help browsing using F1 with a separate command history.
History browsing using F2 that skips output as well as the >>> and … prompts.
“Paste mode” with F3 that makes pasting larger blocks of code easier (press F3 again to return to the regular prompt).
To disable the new interactive shell,
set the PYTHON_BASIC_REPL
environment variable.
For more on interactive mode, see Interactive Mode.
(Contributed by Pablo Galindo Salgado, Łukasz Langa, and Lysandros Nikolaou in gh-111201 based on code from the PyPy project. Windows support contributed by Dino Viehland and Anthony Shaw.)
Improved error messages¶
The interpreter now uses color by default when displaying tracebacks in the terminal. This feature can be controlled via the new
PYTHON_COLORS
environment variable as well as the canonicalNO_COLOR
andFORCE_COLOR
environment variables. (Contributed by Pablo Galindo Salgado in gh-112730.)A common mistake is to write a script with the same name as a standard library module. When this results in errors, we now display a more helpful error message:
$ python random.py Traceback (most recent call last): File "/home/me/random.py", line 1, in <module> import random File "/home/me/random.py", line 3, in <module> print(random.randint(5)) ^^^^^^^^^^^^^^ AttributeError: module 'random' has no attribute 'randint' (consider renaming '/home/me/random.py' since it has the same name as the standard library module named 'random' and prevents importing that standard library module)
Similarly, if a script has the same name as a third-party module that it attempts to import and this results in errors, we also display a more helpful error message:
$ python numpy.py Traceback (most recent call last): File "/home/me/numpy.py", line 1, in <module> import numpy as np File "/home/me/numpy.py", line 3, in <module> np.array([1, 2, 3]) ^^^^^^^^ AttributeError: module 'numpy' has no attribute 'array' (consider renaming '/home/me/numpy.py' if it has the same name as a library you intended to import)
(Contributed by Shantanu Jain in gh-95754.)
The error message now tries to suggest the correct keyword argument when an incorrect keyword argument is passed to a function.
>>> "Better error messages!".split(max_split=1) Traceback (most recent call last): File "<python-input-0>", line 1, in <module> "Better error messages!".split(max_split=1) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^ TypeError: split() got an unexpected keyword argument 'max_split'. Did you mean 'maxsplit'?
(Contributed by Pablo Galindo Salgado and Shantanu Jain in gh-107944.)
Free-threaded CPython¶
CPython now has experimental support for running in a free-threaded mode,
with the global interpreter lock (GIL) disabled.
This is an experimental feature and therefore is not enabled by default.
The free-threaded mode requires a different executable,
usually called python3.13t
or python3.13t.exe
.
Pre-built binaries marked as free-threaded can be installed as part of
the official Windows
and macOS installers,
or CPython can be built from source with the --disable-gil
option.
Free-threaded execution allows for full utilization of the available
processing power by running threads in parallel on available CPU cores.
While not all software will benefit from this automatically, programs
designed with threading in mind will run faster on multi-core hardware.
The free-threaded mode is experimental and work is ongoing to improve it:
expect some bugs and a substantial single-threaded performance hit.
Free-threaded builds of CPython support optionally running with the GIL
enabled at runtime using the environment variable PYTHON_GIL
or
the command-line option -X gil=1
.
To check if the current interpreter supports free-threading, python -VV
and sys.version
contain “experimental free-threading build”.
The new sys._is_gil_enabled()
function can be used to check whether
the GIL is actually disabled in the running process.
C-API extension modules need to be built specifically for the free-threaded
build. Extensions that support running with the GIL disabled should
use the Py_mod_gil
slot. Extensions using single-phase init should
use PyUnstable_Module_SetGIL()
to indicate whether they support
running with the GIL disabled. Importing C extensions that don’t use these
mechanisms will cause the GIL to be enabled, unless the GIL was explicitly
disabled with the PYTHON_GIL
environment variable or the
-X gil=0
option.
pip 24.1 or newer is required to install packages with C extensions in the
free-threaded build.
This work was made possible thanks to many individuals and organizations, including the large community of contributors to Python and third-party projects to test and enable free-threading support. Notable contributors include: Sam Gross, Ken Jin, Donghee Na, Itamar Oren, Matt Page, Brett Simmers, Dino Viehland, Carl Meyer, Nathan Goldbaum, Ralf Gommers, Lysandros Nikolaou, and many others. Many of these contributors are employed by Meta, which has provided significant engineering resources to support this project.
See also
PEP 703 “Making the Global Interpreter Lock Optional in CPython” contains rationale and information surrounding this work.
Porting Extension Modules to Support Free-Threading: A community-maintained porting guide for extension authors.
An experimental just-in-time (JIT) compiler¶
When CPython is configured and built using
the --enable-experimental-jit
option,
a just-in-time (JIT) compiler is added which may speed up some Python programs.
On Windows, use PCbuild/build.bat --experimental-jit
to enable the JIT
or --experimental-jit-interpreter
to enable the Tier 2 interpreter.
Build requirements and further supporting information are contained at
Tools/jit/README.md
.
The --enable-experimental-jit
option takes these (optional) values,
defaulting to yes
if --enable-experimental-jit
is present
without the optional value.
no
: Disable the entire Tier 2 and JIT pipeline.yes
: Enable the JIT. To disable the JIT at runtime, pass the environment variablePYTHON_JIT=0
.yes-off
: Build the JIT but disable it by default. To enable the JIT at runtime, pass the environment variablePYTHON_JIT=1
.interpreter
: Enable the Tier 2 interpreter but disable the JIT. The interpreter can be disabled by running withPYTHON_JIT=0
.
The internal architecture is roughly as follows:
We start with specialized Tier 1 bytecode. See What’s new in 3.11 for details.
When the Tier 1 bytecode gets hot enough, it gets translated to a new purely internal intermediate representation (IR), called the Tier 2 IR, and sometimes referred to as micro-ops (“uops”).
The Tier 2 IR uses the same stack-based virtual machine as Tier 1, but the instruction format is better suited to translation to machine code.
We have several optimization passes for Tier 2 IR, which are applied before it is interpreted or translated to machine code.
There is a Tier 2 interpreter, but it is mostly intended for debugging the earlier stages of the optimization pipeline. The Tier 2 interpreter can be enabled by configuring Python with
--enable-experimental-jit=interpreter
.When the JIT is enabled, the optimized Tier 2 IR is translated to machine code, which is then executed.
The machine code translation process uses a technique called copy-and-patch. It has no runtime dependencies, but there is a new build-time dependency on LLVM.
See also
(JIT by Brandt Bucher, inspired by a paper by Haoran Xu and Fredrik Kjolstad. Tier 2 IR by Mark Shannon and Guido van Rossum. Tier 2 optimizer by Ken Jin.)
Defined mutation semantics for locals()
¶
Historically, the expected result of mutating the return value of
locals()
has been left to individual Python implementations to define.
Starting from Python 3.13, PEP 667 standardises
the historical behavior of CPython for most code execution scopes,
but changes optimized scopes
(functions, generators, coroutines, comprehensions, and generator expressions)
to explicitly return independent snapshots of the currently assigned local
variables, including locally referenced nonlocal variables captured in closures.
This change to the semantics of locals()
in optimized scopes also
affects the default behavior of code execution functions that implicitly
target locals()
if no explicit namespace is provided
(such as exec()
and eval()
).
In previous versions, whether or not changes could be accessed by calling
locals()
after calling the code execution function was
implementation-dependent. In CPython specifically, such code would typically
appear to work as desired, but could sometimes fail in optimized scopes based
on other code (including debuggers and code execution tracing tools)
potentially resetting the shared snapshot in that scope.
Now, the code will always run against an independent snapshot of
the local variables in optimized scopes, and hence the changes will never
be visible in subsequent calls to locals()
.
To access the changes made in these cases, an explicit namespace reference
must now be passed to the relevant function.
Alternatively, it may make sense to update affected code to use a higher level
code execution API that returns the resulting code execution namespace
(e.g. runpy.run_path()
when executing Python files from disk).
To ensure debuggers and similar tools can reliably update local variables in
scopes affected by this change, FrameType.f_locals
now
returns a write-through proxy to the frame’s local and locally referenced
nonlocal variables in these scopes, rather than returning an inconsistently
updated shared dict
instance with undefined runtime semantics.
See PEP 667 for more details, including related C API changes and deprecations. Porting notes are also provided below for the affected Python APIs and C APIs.
(PEP and implementation contributed by Mark Shannon and Tian Gao in gh-74929. Documentation updates provided by Guido van Rossum and Alyssa Coghlan.)
Support for mobile platforms¶
PEP 730: iOS is now a PEP 11 supported platform, with the
arm64-apple-ios
and arm64-apple-ios-simulator
targets at tier 3
(iPhone and iPad devices released after 2013 and the Xcode iOS simulator
running on Apple silicon hardware, respectively).
x86_64-apple-ios-simulator
(the Xcode iOS simulator running on older x86_64
hardware)
is not a tier 3 supported platform, but will have best-effort support.
(PEP written and implementation contributed by Russell Keith-Magee in
gh-114099.)
PEP 738: Android is now a PEP 11 supported platform, with the
aarch64-linux-android
and x86_64-linux-android
targets at tier 3.
The 32-bit targets arm-linux-androideabi
and i686-linux-android
are not tier 3 supported platforms, but will have best-effort support.
(PEP written and implementation contributed by Malcolm Smith in
gh-116622.)
Other Language Changes¶
The compiler now strips common leading whitespace from every line in a docstring. This reduces the size of the bytecode cache (such as
.pyc
files), with reductions in file size of around 5%, for example insqlalchemy.orm.session
from SQLAlchemy 2.0. This change affects tools that use docstrings, such asdoctest
.>>> def spam(): ... """ ... This is a docstring with ... leading whitespace. ... ... It even has multiple paragraphs! ... """ ... >>> spam.__doc__ '\nThis is a docstring with\n leading whitespace.\n\nIt even has multiple paragraphs!\n'
(Contributed by Inada Naoki in gh-81283.)
Annotation scopes within class scopes can now contain lambdas and comprehensions. Comprehensions that are located within class scopes are not inlined into their parent scope.
class C[T]: type Alias = lambda: T
Future statements are no longer triggered by relative imports of the
__future__
module, meaning that statements of the formfrom .__future__ import ...
are now simply standard relative imports, with no special features activated. (Contributed by Jeremiah Gabriel Pascual in gh-118216.)global
declarations are now permitted inexcept
blocks when that global is used in theelse
block. Previously this raised an erroneousSyntaxError
. (Contributed by Irit Katriel in gh-111123.)Add
PYTHON_FROZEN_MODULES
, a new environment variable that determines whether frozen modules are ignored by the import machinery, equivalent to the-X frozen_modules
command-line option. (Contributed by Yilei Yang in gh-111374.)Add support for the perf profiler working without frame pointers through the new environment variable
PYTHON_PERF_JIT_SUPPORT
and command-line option-X perf_jit
. (Contributed by Pablo Galindo in gh-118518.)The location of a
.python_history
file can be changed via the newPYTHON_HISTORY
environment variable. (Contributed by Levi Sabah, Zackery Spytz and Hugo van Kemenade in gh-73965.)Classes have a new
__static_attributes__
attribute. This is populated by the compiler with a tuple of the class’s attribute names which are assigned throughself.<name>
from any function in its body. (Contributed by Irit Katriel in gh-115775.)The compiler now creates a
__firstlineno__
attribute on classes with the line number of the first line of the class definition. (Contributed by Serhiy Storchaka in gh-118465.)The
exec()
andeval()
builtins now accept the globals and locals arguments as keywords. (Contributed by Raphael Gaschignard in gh-105879)The
compile()
builtin now accepts a new flag,ast.PyCF_OPTIMIZED_AST
, which is similar toast.PyCF_ONLY_AST
except that the returned AST is optimized according to the value of the optimize argument. (Contributed by Irit Katriel in gh-108113).Add a
__name__
attribute onproperty
objects. (Contributed by Eugene Toder in gh-101860.)Add
PythonFinalizationError
, a new exception derived fromRuntimeError
and used to signal when operations are blocked during finalization. The following callables now raisePythonFinalizationError
, instead ofRuntimeError
:(Contributed by Victor Stinner in gh-114570.)
Allow the count argument of
str.replace()
to be a keyword. (Contributed by Hugo van Kemenade in gh-106487.)Many functions now emit a warning if a boolean value is passed as a file descriptor argument. This can help catch some errors earlier. (Contributed by Serhiy Storchaka in gh-82626.)
Added
name
andmode
attributes for compressed and archived file-like objects in thebz2
,lzma
,tarfile
, andzipfile
modules. (Contributed by Serhiy Storchaka in gh-115961.)
New Modules¶
dbm.sqlite3
: An SQLite backend fordbm
. (Contributed by Raymond Hettinger and Erlend E. Aasland in gh-100414.)
Improved Modules¶
argparse¶
Add the deprecated parameter to the
add_argument()
andadd_parser()
methods, to enable deprecating command-line options, positional arguments, and subcommands. (Contributed by Serhiy Storchaka in gh-83648.)
array¶
Add the
'w'
type code (Py_UCS4
) for Unicode characters. It should be used instead of the deprecated'u'
type code. (Contributed by Inada Naoki in gh-80480.)Register
array.array
as aMutableSequence
by implementing theclear()
method. (Contributed by Mike Zimin in gh-114894.)
ast¶
The constructors of node types in the
ast
module are now stricter in the arguments they accept, with more intuitive behavior when arguments are omitted.If an optional field on an AST node is not included as an argument when constructing an instance, the field will now be set to
None
. Similarly, if a list field is omitted, that field will now be set to an empty list, and if anexpr_context
field is omitted, it defaults toLoad()
. (Previously, in all cases, the attribute would be missing on the newly constructed AST node instance.)In all other cases, where a required argument is omitted, the node constructor will emit a
DeprecationWarning
. This will raise an exception in Python 3.15. Similarly, passing a keyword argument to the constructor that does not map to a field on the AST node is now deprecated, and will raise an exception in Python 3.15.These changes do not apply to user-defined subclasses of
ast.AST
unless the class opts in to the new behavior by defining theAST._field_types
mapping.(Contributed by Jelle Zijlstra in gh-105858, gh-117486, and gh-118851.)
ast.parse()
now accepts an optional argument optimize which is passed on tocompile()
. This makes it possible to obtain an optimized AST. (Contributed by Irit Katriel in gh-108113.)
asyncio¶
asyncio.as_completed()
now returns an object that is both an asynchronous iterator and a plain iterator of awaitables. The awaitables yielded by asynchronous iteration include original task or future objects that were passed in, making it easier to associate results with the tasks being completed. (Contributed by Justin Arthur in gh-77714.)asyncio.loop.create_unix_server()
will now automatically remove the Unix socket when the server is closed. (Contributed by Pierre Ossman in gh-111246.)DatagramTransport.sendto()
will now send zero-length datagrams if called with an empty bytes object. The transport flow control also now accounts for the datagram header when calculating the buffer size. (Contributed by Jamie Phan in gh-115199.)Add
Queue.shutdown
andQueueShutDown
to manage queue termination. (Contributed by Laurie Opperman and Yves Duprat in gh-104228.)Add the
Server.close_clients()
andServer.abort_clients()
methods, which more forcefully close an asyncio server. (Contributed by Pierre Ossman in gh-113538.)Accept a tuple of separators in
StreamReader.readuntil()
, stopping when any one of them is encountered. (Contributed by Bruce Merry in gh-81322.)Improve the behavior of
TaskGroup
when an external cancellation collides with an internal cancellation. For example, when two task groups are nested and both experience an exception in a child task simultaneously, it was possible that the outer task group would hang, because its internal cancellation was swallowed by the inner task group.In the case where a task group is cancelled externally and also must raise an
ExceptionGroup
, it will now call the parent task’scancel()
method. This ensures that aCancelledError
will be raised at the nextawait
, so the cancellation is not lost.An added benefit of these changes is that task groups now preserve the cancellation count (
cancelling()
).In order to handle some corner cases,
uncancel()
may now reset the undocumented_must_cancel
flag when the cancellation count reaches zero.(Inspired by an issue reported by Arthur Tacca in gh-116720.)
When
TaskGroup.create_task()
is called on an inactiveTaskGroup
, the given coroutine will be closed (which prevents aRuntimeWarning
about the given coroutine being never awaited). (Contributed by Arthur Tacca and Jason Zhang in gh-115957.)The function and methods named
create_task
have received a new**kwargs
argument that is passed through to the task constructor. This change was accidentally added in 3.13.3, and broke the API contract for custom task factories. Several third-party task factories implemented workarounds for this. In 3.13.4 and later releases the old factory contract is honored once again (until 3.14). To keep the workarounds working, the extra**kwargs
argument still allows passing additional keyword arguments toTask
and to custom task factories.This affects the following function and methods:
asyncio.create_task()
,asyncio.loop.create_task()
,asyncio.TaskGroup.create_task()
. (Contributed by Thomas Grainger in gh-128307.)
base64¶
Add
z85encode()
andz85decode()
functions for encodingbytes
as Z85 data and decoding Z85-encoded data tobytes
. (Contributed by Matan Perelman in gh-75299.)
compileall¶
The default number of worker threads and processes is now selected using
os.process_cpu_count()
instead ofos.cpu_count()
. (Contributed by Victor Stinner in gh-109649.)
concurrent.futures¶
The default number of worker threads and processes is now selected using
os.process_cpu_count()
instead ofos.cpu_count()
. (Contributed by Victor Stinner in gh-109649.)
configparser¶
ConfigParser
now has support for unnamed sections, which allows for top-level key-value pairs. This can be enabled with the new allow_unnamed_section parameter. (Contributed by Pedro Sousa Lacerda in gh-66449.)
copy¶
The new
replace()
function and thereplace protocol
make creating modified copies of objects much simpler. This is especially useful when working with immutable objects. The following types support thereplace()
function and implement the replace protocol:Any user-defined class can also support
copy.replace()
by defining the__replace__()
method. (Contributed by Serhiy Storchaka in gh-108751.)
ctypes¶
As a consequence of necessary internal refactoring, initialization of internal metaclasses now happens in
__init__
rather than in__new__
. This affects projects that subclass these internal metaclasses to provide custom initialization. Generally:Custom logic that was done in
__new__
after callingsuper().__new__
should be moved to__init__
.To create a class, call the metaclass, not only the metaclass’s
__new__
method.
See gh-124520 for discussion and links to changes in some affected projects.
ctypes.Structure
objects have a new_align_
attribute which allows the alignment of the structure being packed to/from memory to be specified explicitly. (Contributed by Matt Sanderson in gh-112433)
dbm¶
Add
dbm.sqlite3
, a new module which implements an SQLite backend, and make it the defaultdbm
backend. (Contributed by Raymond Hettinger and Erlend E. Aasland in gh-100414.)Allow removing all items from the database through the new
clear()
methods of the GDBM and NDBM database objects. (Contributed by Donghee Na in gh-107122.)
dis¶
Change the output of
dis
module functions to show logical labels for jump targets and exception handlers, rather than offsets. The offsets can be added with the new-O
command-line option or the show_offsets argument. (Contributed by Irit Katriel in gh-112137.)get_instructions()
no longer represents cache entries as separate instructions. Instead, it returns them as part of theInstruction
, in the new cache_info field. The show_caches argument toget_instructions()
is deprecated and no longer has any effect. (Contributed by Irit Katriel in gh-112962.)
doctest¶
doctest
output is now colored by default. This can be controlled via the newPYTHON_COLORS
environment variable as well as the canonicalNO_COLOR
andFORCE_COLOR
environment variables. See also Controlling color. (Contributed by Hugo van Kemenade in gh-117225.)The
DocTestRunner.run()
method now counts the number of skipped tests. Add theDocTestRunner.skips
andTestResults.skipped
attributes. (Contributed by Victor Stinner in gh-108794.)
email¶
Headers with embedded newlines are now quoted on output. The
generator
will now refuse to serialize (write) headers that are improperly folded or delimited, such that they would be parsed as multiple headers or joined with adjacent data. If you need to turn this safety feature off, setverify_generated_headers
. (Contributed by Bas Bloemsaat and Petr Viktorin in gh-121650.)getaddresses()
andparseaddr()
now return('', '')
pairs in more situations where invalid email addresses are encountered instead of potentially inaccurate values. The two functions have a new optional strict parameter (defaultTrue
). To get the old behavior (accepting malformed input), usestrict=False
.getattr(email.utils, 'supports_strict_parsing', False)
can be used to check if the strict parameter is available. (Contributed by Thomas Dwyer and Victor Stinner for gh-102988 to improve the CVE 2023-27043 fix.)
enum¶
fractions¶
Fraction
objects now support the standard format specification mini-language rules for fill, alignment, sign handling, minimum width, and grouping. (Contributed by Mark Dickinson in gh-111320.)
glob¶
Add
translate()
, a function to convert a path specification with shell-style wildcards to a regular expression. (Contributed by Barney Gale in gh-72904.)
importlib¶
The following functions in
importlib.resources
now allow accessing a directory (or tree) of resources, using multiple positional arguments (the encoding and errors arguments in the text-reading functions are now keyword-only):These functions are no longer deprecated and are not scheduled for removal. (Contributed by Petr Viktorin in gh-116608.)
contents()
remains deprecated in favor of the fully-featuredTraversable
API. However, there is now no plan to remove it. (Contributed by Petr Viktorin in gh-116608.)
io¶
The
IOBase
finalizer now logs any errors raised by theclose()
method withsys.unraisablehook
. Previously, errors were ignored silently by default, and only logged in Python Development Mode or when using a Python debug build. (Contributed by Victor Stinner in gh-62948.)
ipaddress¶
Add the
IPv4Address.ipv6_mapped
property, which returns the IPv4-mapped IPv6 address. (Contributed by Charles Machalow in gh-109466.)Fix
is_global
andis_private
behavior inIPv4Address
,IPv6Address
,IPv4Network
, andIPv6Network
. (Contributed by Jakub Stasiak in gh-113171.)
itertools¶
batched()
has a new strict parameter, which raises aValueError
if the final batch is shorter than the specified batch size. (Contributed by Raymond Hettinger in gh-113202.)
marshal¶
Add the allow_code parameter in module functions. Passing
allow_code=False
prevents serialization and de-serialization of code objects which are incompatible between Python versions. (Contributed by Serhiy Storchaka in gh-113626.)
math¶
The new function
fma()
performs fused multiply-add operations. This computesx * y + z
with only a single round, and so avoids any intermediate loss of precision. It wraps thefma()
function provided by C99, and follows the specification of the IEEE 754 “fusedMultiplyAdd” operation for special cases. (Contributed by Mark Dickinson and Victor Stinner in gh-73468.)
mimetypes¶
Add the
guess_file_type()
function to guess a MIME type from a filesystem path. Using paths withguess_type()
is now soft deprecated. (Contributed by Serhiy Storchaka in gh-66543.)
mmap¶
mmap
is now protected from crashing on Windows when the mapped memory is inaccessible due to file system errors or access violations. (Contributed by Jannis Weigend in gh-118209.)mmap
has a newseekable()
method that can be used when a seekable file-like object is required. Theseek()
method now returns the new absolute position. (Contributed by Donghee Na and Sylvie Liberman in gh-111835.)The new UNIX-only trackfd parameter for
mmap
controls file descriptor duplication; if false, the file descriptor specified by fileno will not be duplicated. (Contributed by Zackery Spytz and Petr Viktorin in gh-78502.)
multiprocessing¶
The default number of worker threads and processes is now selected using
os.process_cpu_count()
instead ofos.cpu_count()
. (Contributed by Victor Stinner in gh-109649.)
os¶
Add
process_cpu_count()
function to get the number of logical CPU cores usable by the calling thread of the current process. (Contributed by Victor Stinner in gh-109649.)cpu_count()
andprocess_cpu_count()
can be overridden through the new environment variablePYTHON_CPU_COUNT
or the new command-line option-X cpu_count
. This option is useful for users who need to limit CPU resources of a container system without having to modify application code or the container itself. (Contributed by Donghee Na in gh-109595.)Add a low level interface to Linux’s timer file descriptors via
timerfd_create()
,timerfd_settime()
,timerfd_settime_ns()
,timerfd_gettime()
,timerfd_gettime_ns()
,TFD_NONBLOCK
,TFD_CLOEXEC
,TFD_TIMER_ABSTIME
, andTFD_TIMER_CANCEL_ON_SET
(Contributed by Masaru Tsuchiyama in gh-108277.)lchmod()
and the follow_symlinks argument ofchmod()
are both now available on Windows. Note that the default value of follow_symlinks inlchmod()
isFalse
on Windows. (Contributed by Serhiy Storchaka in gh-59616.)fchmod()
and support for file descriptors inchmod()
are both now available on Windows. (Contributed by Serhiy Storchaka in gh-113191.)On Windows,
mkdir()
andmakedirs()
now support passing a mode value of0o700
to apply access control to the new directory. This implicitly affectstempfile.mkdtemp()
and is a mitigation for CVE 2024-4030. Other values for mode continue to be ignored. (Contributed by Steve Dower in gh-118486.)posix_spawn()
now acceptsNone
for the env argument, which makes the newly spawned process use the current process environment. (Contributed by Jakub Kulik in gh-113119.)posix_spawn()
can now use thePOSIX_SPAWN_CLOSEFROM
attribute in the file_actions parameter on platforms that supportposix_spawn_file_actions_addclosefrom_np()
. (Contributed by Jakub Kulik in gh-113117.)
os.path¶
Add
isreserved()
to check if a path is reserved on the current system. This function is only available on Windows. (Contributed by Barney Gale in gh-88569.)On Windows,
isabs()
no longer considers paths starting with exactly one slash (\
or/
) to be absolute. (Contributed by Barney Gale and Jon Foster in gh-44626.)realpath()
now resolves MS-DOS style file names even if the file is not accessible. (Contributed by Moonsik Park in gh-82367.)
pathlib¶
Add
UnsupportedOperation
, which is raised instead ofNotImplementedError
when a path operation isn’t supported. (Contributed by Barney Gale in gh-89812.)Add a new constructor for creating
Path
objects from ‘file’ URIs (file:///
),Path.from_uri()
. (Contributed by Barney Gale in gh-107465.)Add
PurePath.full_match()
for matching paths with shell-style wildcards, including the recursive wildcard “**
”. (Contributed by Barney Gale in gh-73435.)Add the
PurePath.parser
class attribute to store the implementation ofos.path
used for low-level path parsing and joining. This will be eitherposixpath
orntpath
.Add recurse_symlinks keyword-only argument to
Path.glob()
andrglob()
. (Contributed by Barney Gale in gh-77609.)Path.glob()
andrglob()
now return files and directories when given a pattern that ends with “**
”. Previously, only directories were returned. (Contributed by Barney Gale in gh-70303.)Add the follow_symlinks keyword-only argument to
Path.is_file
,Path.is_dir
,Path.owner()
, andPath.group()
. (Contributed by Barney Gale in gh-105793 and Kamil Turek in gh-107962.)
pdb¶
breakpoint()
andset_trace()
now enter the debugger immediately rather than on the next line of code to be executed. This change prevents the debugger from breaking outside of the context whenbreakpoint()
is positioned at the end of the context. (Contributed by Tian Gao in gh-118579.)sys.path[0]
is no longer replaced by the directory of the script being debugged whensys.flags.safe_path
is set. (Contributed by Tian Gao and Christian Walther in gh-111762.)zipapp
is now supported as a debugging target. (Contributed by Tian Gao in gh-118501.)Add ability to move between chained exceptions during post-mortem debugging in
pm()
using the newexceptions [exc_number]
command for Pdb. (Contributed by Matthias Bussonnier in gh-106676.)Expressions and statements whose prefix is a pdb command are now correctly identified and executed. (Contributed by Tian Gao in gh-108464.)
queue¶
Add
Queue.shutdown
andShutDown
to manage queue termination. (Contributed by Laurie Opperman and Yves Duprat in gh-104750.)
random¶
Add a command-line interface. (Contributed by Hugo van Kemenade in gh-118131.)
re¶
Rename
re.error
toPatternError
for improved clarity.re.error
is kept for backward compatibility.
shutil¶
site¶
.pth
files are now decoded using UTF-8 first, and then with the locale encoding if UTF-8 decoding fails. (Contributed by Inada Naoki in gh-117802.)
sqlite3¶
A
ResourceWarning
is now emitted if aConnection
object is notclosed
explicitly. (Contributed by Erlend E. Aasland in gh-105539.)Add the filter keyword-only parameter to
Connection.iterdump()
for filtering database objects to dump. (Contributed by Mariusz Felisiak in gh-91602.)
ssl¶
The
create_default_context()
API now includesVERIFY_X509_PARTIAL_CHAIN
andVERIFY_X509_STRICT
in its default flags.Note
VERIFY_X509_STRICT
may reject pre-RFC 5280 or malformed certificates that the underlying OpenSSL implementation might otherwise accept. Whilst disabling this is not recommended, you can do so using:import ssl ctx = ssl.create_default_context() ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT
(Contributed by William Woodruff in gh-112389.)
statistics¶
Add
kde()
for kernel density estimation. This makes it possible to estimate a continuous probability density function from a fixed number of discrete samples. (Contributed by Raymond Hettinger in gh-115863.)Add
kde_random()
for sampling from an estimated probability density function created bykde()
. (Contributed by Raymond Hettinger in gh-115863.)
subprocess¶
The
subprocess
module now uses theposix_spawn()
function in more situations.Notably, when close_fds is
True
(the default),posix_spawn()
will be used when the C library providesposix_spawn_file_actions_addclosefrom_np()
, which includes recent versions of Linux, FreeBSD, and Solaris. On Linux, this should perform similarly to the existing Linuxvfork()
based code.A private control knob
subprocess._USE_POSIX_SPAWN
can be set toFalse
if you need to forcesubprocess
to never useposix_spawn()
. Please report your reason and platform details in the issue tracker if you set this so that we can improve our API selection logic for everyone. (Contributed by Jakub Kulik in gh-113117.)
sys¶
Add the
_is_interned()
function to test if a string was interned. This function is not guaranteed to exist in all implementations of Python. (Contributed by Serhiy Storchaka in gh-78573.)
tempfile¶
On Windows, the default mode
0o700
used bytempfile.mkdtemp()
now limits access to the new directory due to changes toos.mkdir()
. This is a mitigation for CVE 2024-4030. (Contributed by Steve Dower in gh-118486.)
time¶
On Windows,
monotonic()
now uses theQueryPerformanceCounter()
clock for a resolution of 1 microsecond, instead of theGetTickCount64()
clock which has a resolution of 15.6 milliseconds. (Contributed by Victor Stinner in gh-88494.)On Windows,
time()
now uses theGetSystemTimePreciseAsFileTime()
clock for a resolution of 1 microsecond, instead of theGetSystemTimeAsFileTime()
clock which has a resolution of 15.6 milliseconds. (Contributed by Victor Stinner in gh-63207.)
tkinter¶
Add
tkinter
widget methods:tk_busy_hold()
,tk_busy_configure()
,tk_busy_cget()
,tk_busy_forget()
,tk_busy_current()
, andtk_busy_status()
. (Contributed by Miguel, klappnase and Serhiy Storchaka in gh-72684.)The
tkinter
widget methodwm_attributes()
now accepts the attribute name without the minus prefix to get window attributes, for examplew.wm_attributes('alpha')
and allows specifying attributes and values to set as keyword arguments, for examplew.wm_attributes(alpha=0.5)
. (Contributed by Serhiy Storchaka in gh-43457.)wm_attributes()
can now return attributes as adict
, by using the new optional keyword-only parameter return_python_dict. (Contributed by Serhiy Storchaka in gh-43457.)Text.count()
can now return a simpleint
when the new optional keyword-only parameter return_ints is used. Otherwise, the single count is returned as a 1-tuple orNone
. (Contributed by Serhiy Storchaka in gh-97928.)Support the “vsapi” element type in the
element_create()
method oftkinter.ttk.Style
. (Contributed by Serhiy Storchaka in gh-68166.)Add the
after_info()
method for Tkinter widgets. (Contributed by Cheryl Sabella in gh-77020.)Add a new
copy_replace()
method toPhotoImage
to copy a region from one image to another, possibly with pixel zooming, subsampling, or both. (Contributed by Serhiy Storchaka in gh-118225.)Add from_coords parameter to the
PhotoImage
methodscopy()
,zoom()
andsubsample()
. Add zoom and subsample parameters to thePhotoImage
methodcopy()
. (Contributed by Serhiy Storchaka in gh-118225.)Add the
PhotoImage
methodsread()
to read an image from a file anddata()
to get the image data. Add background and grayscale parameters to thewrite()
method. (Contributed by Serhiy Storchaka in gh-118271.)
traceback¶
Add the
exc_type_str
attribute toTracebackException
, which holds a string display of the exc_type. Deprecate theexc_type
attribute, which holds the type object itself. Add parameter save_exc_type (defaultTrue
) to indicate whetherexc_type
should be saved. (Contributed by Irit Katriel in gh-112332.)Add a new show_group keyword-only parameter to
TracebackException.format_exception_only()
to (recursively) format the nested exceptions of aBaseExceptionGroup
instance. (Contributed by Irit Katriel in gh-105292.)
types¶
SimpleNamespace
can now take a single positional argument to initialise the namespace’s arguments. This argument must either be a mapping or an iterable of key-value pairs. (Contributed by Serhiy Storchaka in gh-108191.)
typing¶
PEP 705: Add
ReadOnly
, a special typing construct to mark aTypedDict
item as read-only for type checkers.PEP 742: Add
TypeIs
, a typing construct that can be used to instruct a type checker how to narrow a type.Add
NoDefault
, a sentinel object used to represent the defaults of some parameters in thetyping
module. (Contributed by Jelle Zijlstra in gh-116126.)Add
get_protocol_members()
to return the set of members defining atyping.Protocol
. (Contributed by Jelle Zijlstra in gh-104873.)Add
is_protocol()
to check whether a class is aProtocol
. (Contributed by Jelle Zijlstra in gh-104873.)ClassVar
can now be nested inFinal
, and vice versa. (Contributed by Mehdi Drissi in gh-89547.)
unicodedata¶
Update the Unicode database to version 15.1.0. (Contributed by James Gerity in gh-109559.)
venv¶
Add support for creating source control management (SCM) ignore files in a virtual environment’s directory. By default, Git is supported. This is implemented as opt-in via the API, which can be extended to support other SCMs (
EnvBuilder
andcreate()
), and opt-out via the CLI, using--without-scm-ignore-files
. (Contributed by Brett Cannon in gh-108125.)
warnings¶
PEP 702: The new
warnings.deprecated()
decorator provides a way to communicate deprecations to a static type checker and to warn on usage of deprecated classes and functions. ADeprecationWarning
may also be emitted when a decorated function or class is used at runtime. (Contributed by Jelle Zijlstra in gh-104003.)
xml¶
Allow controlling Expat >=2.6.0 reparse deferral (CVE 2023-52425) by adding five new methods:
xml.sax.expatreader.ExpatParser.flush()
(Contributed by Sebastian Pipping in gh-115623.)
Add the
close()
method for the iterator returned byiterparse()
for explicit cleanup. (Contributed by Serhiy Storchaka in gh-69893.)
zipimport¶
Optimizations¶
Several standard library modules have had their import times significantly improved. For example, the import time of the
typing
module has been reduced by around a third by removing dependencies onre
andcontextlib
. Other modules to enjoy import-time speedups includeemail.utils
,enum
,functools
,importlib.metadata
, andthreading
. (Contributed by Alex Waygood, Shantanu Jain, Adam Turner, Daniel Hollas, and others in gh-109653.)textwrap.indent()
is now around 30% faster than before for large input. (Contributed by Inada Naoki in gh-107369.)The
subprocess
module now uses theposix_spawn()
function in more situations, including when close_fds isTrue
(the default) on many modern platforms. This should provide a notable performance increase when launching processes on FreeBSD and Solaris. See the subprocess section above for details. (Contributed by Jakub Kulik in gh-113117.)
Removed Modules And APIs¶
PEP 594: Remove “dead batteries” from the standard library¶
PEP 594 proposed removing 19 modules from the standard library, colloquially referred to as ‘dead batteries’ due to their historic, obsolete, or insecure status. All of the following modules were deprecated in Python 3.11, and are now removed:
aifc
standard-aifc: Use the redistribution of
aifc
library from PyPI.
audioop
audioop-lts: Use
audioop-lts
library from PyPI.
chunk
standard-chunk: Use the redistribution of
chunk
library from PyPI.
cgi
andcgitb
cgi.FieldStorage
can typically be replaced withurllib.parse.parse_qsl()
forGET
andHEAD
requests, and theemail.message
module or the multipart library forPOST
andPUT
requests.cgi.parse()
can be replaced by callingurllib.parse.parse_qs()
directly on the desired query string, unless the input ismultipart/form-data
, which should be replaced as described below forcgi.parse_multipart()
.cgi.parse_header()
can be replaced with the functionality in theemail
package, which implements the same MIME RFCs. For example, withemail.message.EmailMessage
:from email.message import EmailMessage msg = EmailMessage() msg['content-type'] = 'application/json; charset="utf8"' main, params = msg.get_content_type(), msg['content-type'].params
cgi.parse_multipart()
can be replaced with the functionality in theemail
package, which implements the same MIME RFCs, or with the multipart library. For example, theemail.message.EmailMessage
andemail.message.Message
classes.standard-cgi: and standard-cgitb: Use the redistribution of
cgi
andcgitb
library from PyPI.
crypt
and the private_crypt
extension. Thehashlib
module may be an appropriate replacement when simply hashing a value is required. Otherwise, various third-party libraries on PyPI are available:bcrypt: Modern password hashing for your software and your servers.
argon2-cffi: The secure Argon2 password hashing algorithm.
legacycrypt:
ctypes
wrapper to the POSIX crypt library call and associated functionality.crypt_r: Fork of the
crypt
module, wrapper to the crypt_r(3) library call and associated functionality.standard-crypt and deprecated-crypt-alternative: Use the redistribution of
crypt
and reimplementation of_crypt
libraries from PyPI.
imghdr
: The filetype, puremagic, or python-magic libraries should be used as replacements. For example, thepuremagic.what()
function can be used to replace theimghdr.what()
function for all file formats that were supported byimghdr
.standard-imghdr: Use the redistribution of
imghdr
library from PyPI.
mailcap
: Use themimetypes
module instead.standard-mailcap: Use the redistribution of
mailcap
library from PyPI.
msilib
nis
nntplib
: Use the pynntp library from PyPI instead.standard-nntplib: Use the redistribution of
nntplib
library from PyPI.
ossaudiodev
: For audio playback, use the pygame library from PyPI instead.pipes
: Use thesubprocess
module instead. Useshlex.quote()
to replace the undocumentedpipes.quote
function.standard-pipes: Use the redistribution of
pipes
library from PyPI.
sndhdr
: The filetype, puremagic, or python-magic libraries should be used as replacements.standard-sndhdr: Use the redistribution of
sndhdr
library from PyPI.
spwd
: Use the python-pam library from PyPI instead.sunau
standard-sunau: Use the redistribution of
sunau
library from PyPI.
telnetlib
, Use the telnetlib3 or Exscript libraries from PyPI instead.standard-telnetlib: Use the redistribution of
telnetlib
library from PyPI.
uu
: Use thebase64
module instead, as a modern alternative.standard-uu: Use the redistribution of
uu
library from PyPI.
xdrlib
standard-xdrlib: Use the redistribution of
xdrlib
library from PyPI.
(Contributed by Victor Stinner and Zachary Ware in gh-104773 and gh-104780.)
2to3¶
Remove the 2to3 program and the
lib2to3
module, previously deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104780.)
builtins¶
Remove support for chained
classmethod
descriptors (introduced in gh-63272). These can no longer be used to wrap other descriptors, such asproperty
. The core design of this feature was flawed and led to several problems. To “pass-through” aclassmethod
, consider using the__wrapped__
attribute that was added in Python 3.10. (Contributed by Raymond Hettinger in gh-89519.)Raise a
RuntimeError
when callingframe.clear()
on a suspended frame (as has always been the case for an executing frame). (Contributed by Irit Katriel in gh-79932.)
configparser¶
Remove the undocumented
LegacyInterpolation
class, deprecated in the docstring since Python 3.2, and at runtime since Python 3.11. (Contributed by Hugo van Kemenade in gh-104886.)
importlib.metadata¶
Remove deprecated subscript (
__getitem__()
) access for EntryPoint objects. (Contributed by Jason R. Coombs in gh-113175.)
locale¶
Remove the
locale.resetlocale()
function, deprecated in Python 3.11. Uselocale.setlocale(locale.LC_ALL, "")
instead. (Contributed by Victor Stinner in gh-104783.)
opcode¶
Move
opcode.ENABLE_SPECIALIZATION
to_opcode.ENABLE_SPECIALIZATION
. This field was added in 3.12, it was never documented, and is not intended for external use. (Contributed by Irit Katriel in gh-105481.)Remove
opcode.is_pseudo()
,opcode.MIN_PSEUDO_OPCODE
, andopcode.MAX_PSEUDO_OPCODE
, which were added in Python 3.12, but were neither documented nor exposed throughdis
, and were not intended to be used externally. (Contributed by Irit Katriel in gh-105481.)
optparse¶
This module is no longer considered soft deprecated. While
argparse
remains preferred for new projects that aren’t using a third party command line argument processing library, there are aspects of the wayargparse
works that mean the lower leveloptparse
module may provide a better foundation for writing argument processing libraries, and for implementing command line applications which adhere more strictly thanargparse
does to various Unix command line processing conventions that originate in the behaviour of the Cgetopt()
function . (Contributed by Alyssa Coghlan and Serhiy Storchaka in gh-126180.)
pathlib¶
re¶
Remove the undocumented, deprecated, and broken
re.template()
function andre.TEMPLATE
/re.T
flag. (Contributed by Serhiy Storchaka and Nikita Sobolev in gh-105687.)
tkinter.tix¶
Remove the
tkinter.tix
module, deprecated in Python 3.6. The third-party Tix library which the module wrapped is unmaintained. (Contributed by Zachary Ware in gh-75552.)
turtle¶
Remove the
RawTurtle.settiltangle()
method, deprecated in the documentation since Python 3.1 and at runtime since Python 3.11. (Contributed by Hugo van Kemenade in gh-104876.)
typing¶
Remove the
typing.io
andtyping.re
namespaces, deprecated since Python 3.8. The items in those namespaces can be imported directly from thetyping
module. (Contributed by Sebastian Rittau in gh-92871.)Remove the keyword-argument method of creating
TypedDict
types, deprecated in Python 3.11. (Contributed by Tomas Roun in gh-104786.)
unittest¶
Remove the following
unittest
functions, deprecated in Python 3.11:unittest.findTestCases()
unittest.makeSuite()
unittest.getTestCaseNames()
Use
TestLoader
methods instead:(Contributed by Hugo van Kemenade in gh-104835.)
Remove the untested and undocumented
TestProgram.usageExit()
method, deprecated in Python 3.11. (Contributed by Hugo van Kemenade in gh-104992.)
urllib¶
Remove the cafile, capath, and cadefault parameters of the
urllib.request.urlopen()
function, deprecated in Python 3.6. Use the context parameter instead with anSSLContext
instance. Thessl.SSLContext.load_cert_chain()
function can be used to load specific certificates, or letssl.create_default_context()
select the operating system’s trusted certificate authority (CA) certificates. (Contributed by Victor Stinner in gh-105382.)
webbrowser¶
Remove the untested and undocumented
MacOSX
class, deprecated in Python 3.11. Use theMacOSXOSAScript
class (introduced in Python 3.2) instead. (Contributed by Hugo van Kemenade in gh-104804.)Remove the deprecated
MacOSXOSAScript._name
attribute. Use theMacOSXOSAScript.name
attribute instead. (Contributed by Nikita Sobolev in gh-105546.)
New Deprecations¶
-
Deprecate the undocumented
SetPointerType()
function, to be removed in Python 3.15. (Contributed by Victor Stinner in gh-105733.)Soft-deprecate the
ARRAY()
function in favour oftype * length
multiplication. (Contributed by Victor Stinner in gh-105733.)
dis
:-
Deprecate non-integer numbers as arguments to functions and methods that consider plural forms in the
gettext
module, even if no translation was found. (Contributed by Serhiy Storchaka in gh-88434.)
glob
:Deprecate the undocumented
glob0()
andglob1()
functions. Useglob()
and pass a path-like object specifying the root directory to the root_dir parameter instead. (Contributed by Barney Gale in gh-117337.)
-
Deprecate
CGIHTTPRequestHandler
, to be removed in Python 3.15. Process-based CGI HTTP servers have been out of favor for a very long time. This code was outdated, unmaintained, and rarely used. It has a high potential for both security and functionality bugs. (Contributed by Gregory P. Smith in gh-109096.)Deprecate the
--cgi
flag to the python -m http.server command-line interface, to be removed in Python 3.15. (Contributed by Gregory P. Smith in gh-109096.)
-
Soft-deprecate file path arguments to
guess_type()
, useguess_file_type()
instead. (Contributed by Serhiy Storchaka in gh-66543.)
re
:Deprecate passing the optional maxsplit, count, or flags arguments as positional arguments to the module-level
split()
,sub()
, andsubn()
functions. These parameters will become keyword-only in a future version of Python. (Contributed by Serhiy Storchaka in gh-56166.)
-
Deprecate
PurePath.is_reserved()
, to be removed in Python 3.15. Useos.path.isreserved()
to detect reserved paths on Windows. (Contributed by Barney Gale in gh-88569.)
-
Deprecate
java_ver()
, to be removed in Python 3.15. This function is only useful for Jython support, has a confusing API, and is largely untested. (Contributed by Nikita Sobolev in gh-116349.)
-
Deprecate the undocumented
ispackage()
function. (Contributed by Zackery Spytz in gh-64020.)
-
Deprecate passing more than one positional argument to the
connect()
function and theConnection
constructor. The remaining parameters will become keyword-only in Python 3.15. (Contributed by Erlend E. Aasland in gh-107948.)Deprecate passing name, number of arguments, and the callable as keyword arguments for
Connection.create_function()
andConnection.create_aggregate()
These parameters will become positional-only in Python 3.15. (Contributed by Erlend E. Aasland in gh-108278.)Deprecate passing the callback callable by keyword for the
set_authorizer()
,set_progress_handler()
, andset_trace_callback()
Connection
methods. The callback callables will become positional-only in Python 3.15. (Contributed by Erlend E. Aasland in gh-108278.)
sys
:Deprecate the
_enablelegacywindowsfsencoding()
function, to be removed in Python 3.16. Use thePYTHONLEGACYWINDOWSFSENCODING
environment variable instead. (Contributed by Inada Naoki in gh-73427.)
-
Deprecate the undocumented and unused
TarFile.tarfile
attribute, to be removed in Python 3.16. (Contributed in gh-115256.)
-
Deprecate the
TracebackException.exc_type
attribute. UseTracebackException.exc_type_str
instead. (Contributed by Irit Katriel in gh-112332.)
-
Deprecate the undocumented keyword argument syntax for creating
NamedTuple
classes (e.g.Point = NamedTuple("Point", x=int, y=int)
), to be removed in Python 3.15. Use the class-based syntax or the functional syntax instead. (Contributed by Alex Waygood in gh-105566.)Deprecate omitting the fields parameter when creating a
NamedTuple
ortyping.TypedDict
class, and deprecate passingNone
to the fields parameter of both types. Python 3.15 will require a valid sequence for the fields parameter. To create a NamedTuple class with zero fields, useclass NT(NamedTuple): pass
orNT = NamedTuple("NT", ())
. To create a TypedDict class with zero fields, useclass TD(TypedDict): pass
orTD = TypedDict("TD", {})
. (Contributed by Alex Waygood in gh-105566 and gh-105570.)Deprecate the
typing.no_type_check_decorator()
decorator function, to be removed in Python 3.15. After eight years in thetyping
module, it has yet to be supported by any major type checker. (Contributed by Alex Waygood in gh-106309.)Deprecate
typing.AnyStr
. In Python 3.16, it will be removed fromtyping.__all__
, and aDeprecationWarning
will be emitted at runtime when it is imported or accessed. It will be removed entirely in Python 3.18. Use the new type parameter syntax instead. (Contributed by Michael The in gh-107116.)
wave
:Deprecate the
getmark()
,setmark()
, andgetmarkers()
methods of theWave_read
andWave_write
classes, to be removed in Python 3.15. (Contributed by Victor Stinner in gh-105096.)
Pending removal in Python 3.14¶
argparse
: The type, choices, and metavar parameters ofargparse.BooleanOptionalAction
are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in gh-92248.)ast
: The following features have been deprecated in documentation since Python 3.8, now cause aDeprecationWarning
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 gh-90953.)-
The child watcher classes
asyncio.MultiLoopChildWatcher
,asyncio.FastChildWatcher
,asyncio.AbstractChildWatcher
andasyncio.SafeChildWatcher
are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597.)asyncio.set_child_watcher()
,asyncio.get_child_watcher()
,asyncio.AbstractEventLoopPolicy.set_child_watcher()
andasyncio.AbstractEventLoopPolicy.get_child_watcher()
are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597.)The
get_event_loop()
method of the default event loop policy now emits aDeprecationWarning
if there is no current event loop set and it decides to create one. (Contributed by Serhiy Storchaka and Guido van Rossum in gh-100160.)
email
: Deprecated the isdst parameter inemail.utils.localtime()
. (Contributed by Alan Williams in gh-72346.)importlib.abc
deprecated classes:importlib.abc.ResourceReader
importlib.abc.Traversable
importlib.abc.TraversableResources
Use
importlib.resources.abc
classes instead:(Contributed by Jason R. Coombs and Hugo van Kemenade in gh-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 gh-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 (gh-84559). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use theget_context()
orset_start_method()
APIs to explicitly specify when your code requires'fork'
. See Contexts and start methods.pathlib
:is_relative_to()
andrelative_to()
: passing additional arguments is deprecated.pkgutil
:pkgutil.find_loader()
andpkgutil.get_loader()
now raiseDeprecationWarning
; useimportlib.util.find_spec()
instead. (Contributed by Nikita Sobolev in gh-97850.)pty
:master_open()
: usepty.openpty()
.slave_open()
: usepty.openpty()
.
-
version
andversion_info
.execute()
andexecutemany()
if named placeholders are used and parameters is a sequence instead of adict
.
urllib
:urllib.parse.Quoter
is deprecated: it was not intended to be a public API. (Contributed by Gregory P. Smith in gh-88168.)
Pending removal in Python 3.15¶
The import system:
Setting
__cached__
on a module while failing to set__spec__.cached
is deprecated. In Python 3.15,__cached__
will cease to be set or take into consideration by the import system or standard library. (gh-97879)Setting
__package__
on a module while failing to set__spec__.parent
is deprecated. In Python 3.15,__package__
will cease to be set or take into consideration by the import system or standard library. (gh-97879)
-
The undocumented
ctypes.SetPointerType()
function has been deprecated since Python 3.13.
-
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.
-
load_module()
method: useexec_module()
instead.
-
The
getdefaultlocale()
function has been deprecated since Python 3.11. Its removal was originally planned for Python 3.13 (gh-90817), but has been postponed to Python 3.15. Usegetlocale()
,setlocale()
, andgetencoding()
instead. (Contributed by Hugo van Kemenade in gh-111187.)
-
PurePath.is_reserved()
has been deprecated since Python 3.13. Useos.path.isreserved()
to detect reserved paths on Windows.
-
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.
-
The check_home argument of
sysconfig.is_python_build()
has been deprecated since Python 3.12.
-
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.CodeType
: Accessingco_lnotab
was deprecated in PEP 626 since 3.10 and was planned to be removed in 3.12, but it only got a properDeprecationWarning
in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in gh-101866.)
-
The undocumented keyword argument syntax for creating
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
TypedDict
s, failing to pass a value to the fields parameter (TD = TypedDict("TD")
) or passingNone
(TD = TypedDict("TD", None)
) has been deprecated since Python 3.13. Useclass TD(TypedDict): pass
orTD = 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 thetyping
module, it has yet to be supported by any major type checker.
wave
:The
getmark()
,setmark()
, andgetmarkers()
methods of theWave_read
andWave_write
classes have been deprecated since Python 3.13.
-
load_module()
has been deprecated since Python 3.10. Useexec_module()
instead. (Contributed by Jiahao Li in gh-125746.)
Pending removal in Python 3.16¶
The import system:
Setting
__loader__
on a module while failing to set__spec__.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.
-
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.iscoroutinefunction()
is deprecated and will be removed in Python 3.16; useinspect.iscoroutinefunction()
instead. (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)asyncio
policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated:Users should use
asyncio.run()
orasyncio.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 gh-127949.)
-
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
). Usenot x
instead for the logical negation of a Boolean. In the rare case that you need the bitwise inversion of the underlying integer, convert toint
explicitly (~int(x)
).
-
Calling the Python implementation of
functools.reduce()
with function or sequence as keyword arguments has been deprecated since Python 3.14.
-
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 gh-115032.)
-
Valid extensions start with a ‘.’ or are empty for
mimetypes.MimeTypes.add_type()
. Undotted extensions are deprecated and will raise aValueError
in Python 3.16. (Contributed by Hugo van Kemenade in gh-75223.)
-
The
ExecError
exception has been deprecated since Python 3.14. It has not been used by any function inshutil
since Python 3.4, and is now an alias ofRuntimeError
.
-
The
Class.get_methods
method has been deprecated since Python 3.14.
sys
:The
_enablelegacywindowsfsencoding()
function has been deprecated since Python 3.13. Use thePYTHONLEGACYWINDOWSFSENCODING
environment variable instead.
-
The
sysconfig.expand_makefile_vars()
function has been deprecated since Python 3.14. Use thevars
argument ofsysconfig.get_paths()
instead.
-
The undocumented and unused
TarFile.tarfile
attribute has been deprecated since Python 3.13.
Pending removal in Python 3.17¶
-
collections.abc.ByteString
is scheduled for removal in Python 3.17.Use
isinstance(obj, collections.abc.Buffer)
to test ifobj
implements the buffer protocol at runtime. For use in type annotations, either useBuffer
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 bothbytes
andbytearray
. However, since the ABC never had any methods, knowing that an object was an instance ofByteString
never actually told you anything useful about the object. Other common buffer types such asmemoryview
were also never understood as subtypes ofByteString
(either at runtime or by static type checkers).See PEP 688 for more details. (Contributed by Shantanu Jain in gh-91896.)
-
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 liketyping.get_origin()
andtyping.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 ifobj
implements the buffer protocol at runtime. For use in type annotations, either useBuffer
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 bothbytes
andbytearray
. However, since the ABC never had any methods, knowing that an object was an instance ofByteString
never actually told you anything useful about the object. Other common buffer types such asmemoryview
were also never understood as subtypes ofByteString
(either at runtime or by static type checkers).See PEP 688 for more details. (Contributed by Shantanu Jain in gh-91896.)
Pending removal in Python 3.18¶
Pending removal in Python 3.19¶
Pending removal in future versions¶
The following APIs will be removed in the future, although there is currently no date scheduled for their removal.
-
Nesting argument groups and nesting mutually exclusive groups are deprecated.
Passing the undocumented keyword argument prefix_chars to
add_argument_group()
is now deprecated.The
argparse.FileType
type converter is deprecated.
-
Generators:
throw(type, exc, tb)
andathrow(type, exc, tb)
signature is deprecated: usethrow(exc)
andathrow(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 keywordsand
,else
,for
,if
,in
,is
andor
. In a future release it will be changed to a syntax error. (gh-87999)Support for
__index__()
and__int__()
method returning non-int type: these methods will be required to return an instance of a strict subclass ofint
.Support for
__float__()
method returning a strict subclass offloat
: these methods will be required to return an instance offloat
.Support for
__complex__()
method returning a strict subclass ofcomplex
: these methods will be required to return an instance ofcomplex
.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 gh-109218.)
calendar
:calendar.January
andcalendar.February
constants are deprecated and replaced bycalendar.JANUARY
andcalendar.FEBRUARY
. (Contributed by Prince Roshan in gh-103636.)codecs
: useopen()
instead ofcodecs.open()
. (gh-133038)codeobject.co_lnotab
: use thecodeobject.co_lines()
method instead.-
utcnow()
: usedatetime.datetime.now(tz=datetime.UTC)
.utcfromtimestamp()
: usedatetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC)
.
gettext
: Plural value must be an integer.-
cache_from_source()
debug_override parameter is deprecated: use the optimization parameter instead.
-
EntryPoints
tuple interface.Implicit
None
on return values.
logging
: thewarn()
method has been deprecated since Python 3.3, usewarning()
instead.mailbox
: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.os
: Callingos.register_at_fork()
in multi-threaded process.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 gh-91760.)sre_compile
,sre_constants
andsre_parse
modules.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
:set_npn_protocols()
andselected_npn_protocol()
are deprecated: use ALPN instead.ssl.OP_NO_SSL*
optionsssl.OP_NO_TLS*
optionsssl.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()
: usenotify_all()
.threading.Event.isSet()
: useis_set()
.threading.Thread.isDaemon()
,threading.Thread.setDaemon()
: usethreading.Thread.daemon
attribute.threading.Thread.getName()
,threading.Thread.setName()
: usethreading.Thread.name
attribute.threading.currentThread()
: usethreading.current_thread()
.threading.activeCount()
: usethreading.active_count()
.
The internal class
typing._UnionGenericAlias
is no longer used to implementtyping.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 gh-105499.)unittest.IsolatedAsyncioTestCase
: it is deprecated to return a value that is notNone
from a test case.urllib.parse
deprecated functions:urlparse()
insteadsplitattr()
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 anElement
is deprecated. In a future release it will always returnTrue
. Prefer explicitlen(elem)
orelem is not None
tests instead.sys._clear_type_cache()
is deprecated: usesys._clear_internal_caches()
instead.
CPython Bytecode Changes¶
The oparg of
YIELD_VALUE
is now1
if the yield is part of a yield-from or await, and0
otherwise. The oparg ofRESUME
was changed to add a bit indicating if the except-depth is 1, which is needed to optimize closing of generators. (Contributed by Irit Katriel in gh-111354.)
C API Changes¶
New Features¶
Add the PyMonitoring C API for generating PEP 669 monitoring events:
PyMonitoring_FireBranchEvent
(Contributed by Irit Katriel in gh-111997).
Add
PyMutex
, a lightweight mutex that occupies a single byte, and the newPyMutex_Lock()
andPyMutex_Unlock()
functions.PyMutex_Lock()
will release the GIL (if currently held) if the operation needs to block. (Contributed by Sam Gross in gh-108724.)Add the PyTime C API to provide access to system clocks:
PyTime_MIN
andPyTime_MAX
.
(Contributed by Victor Stinner and Petr Viktorin in gh-110850.)
Add the
PyDict_ContainsString()
function with the same behavior asPyDict_Contains()
, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*. (Contributed by Victor Stinner in gh-108314.)Add the
PyDict_GetItemRef()
andPyDict_GetItemStringRef()
functions, which behave similarly toPyDict_GetItemWithError()
, but return a strong reference instead of a borrowed reference. Moreover, these functions return-1
on error, removing the need to checkPyErr_Occurred()
. (Contributed by Victor Stinner in gh-106004.)Add the
PyDict_SetDefaultRef()
function, which behaves similarly toPyDict_SetDefault()
, but returns a strong reference instead of a borrowed reference. This function returns-1
on error,0
on insertion, and1
if the key was already present in the dictionary. (Contributed by Sam Gross in gh-112066.)Add the
PyDict_Pop()
andPyDict_PopString()
functions to remove a key from a dictionary and optionally return the removed value. This is similar todict.pop()
, though there is no default value, andKeyError
is not raised for missing keys. (Contributed by Stefan Behnel and Victor Stinner in gh-111262.)Add the
PyMapping_GetOptionalItem()
andPyMapping_GetOptionalItemString()
functions as alternatives toPyObject_GetItem()
andPyMapping_GetItemString()
respectively. The new functions do not raiseKeyError
if the requested key is missing from the mapping. These variants are more convenient and faster if a missing key should not be treated as a failure. (Contributed by Serhiy Storchaka in gh-106307.)Add the
PyObject_GetOptionalAttr()
andPyObject_GetOptionalAttrString()
functions as alternatives toPyObject_GetAttr()
andPyObject_GetAttrString()
respectively. The new functions do not raiseAttributeError
if the requested attribute is not found on the object. These variants are more convenient and faster if the missing attribute should not be treated as a failure. (Contributed by Serhiy Storchaka in gh-106521.)Add the
PyErr_FormatUnraisable()
function as an extension toPyErr_WriteUnraisable()
that allows customizing the warning message. (Contributed by Serhiy Storchaka in gh-108082.)Add new functions that return a strong reference instead of a borrowed reference for frame locals, globals, and builtins, as part of PEP 667:
(Contributed by Mark Shannon and Tian Gao in gh-74929.)
Add the
Py_GetConstant()
andPy_GetConstantBorrowed()
functions to get strong or borrowed references to constants. For example,Py_GetConstant(Py_CONSTANT_ZERO)
returns a strong reference to the constant zero. (Contributed by Victor Stinner in gh-115754.)Add the
PyImport_AddModuleRef()
function as a replacement forPyImport_AddModule()
that returns a strong reference instead of a borrowed reference. (Contributed by Victor Stinner in gh-105922.)Add the
Py_IsFinalizing()
function to check whether the main Python interpreter is shutting down. (Contributed by Victor Stinner in gh-108014.)Add the
PyList_GetItemRef()
function as a replacement forPyList_GetItem()
that returns a strong reference instead of a borrowed reference. (Contributed by Sam Gross in gh-114329.)Add the
PyList_Extend()
andPyList_Clear()
functions, mirroring the Pythonlist.extend()
andlist.clear()
methods. (Contributed by Victor Stinner in gh-111138.)Add the
PyLong_AsInt()
function. It behaves similarly toPyLong_AsLong()
, but stores the result in a C int instead of a C long. (Contributed by Victor Stinner in gh-108014.)Add the
PyLong_AsNativeBytes()
,PyLong_FromNativeBytes()
, andPyLong_FromUnsignedNativeBytes()
functions to simplify converting between native integer types and Pythonint
objects. (Contributed by Steve Dower in gh-111140.)Add
PyModule_Add()
function, which is similar toPyModule_AddObjectRef()
andPyModule_AddObject()
, but always steals a reference to the value. (Contributed by Serhiy Storchaka in gh-86493.)Add the
PyObject_GenericHash()
function that implements the default hashing function of a Python object. (Contributed by Serhiy Storchaka in gh-113024.)Add the
Py_HashPointer()
function to hash a raw pointer. (Contributed by Victor Stinner in gh-111545.)Add the
PyObject_VisitManagedDict()
andPyObject_ClearManagedDict()
functions. which must be called by the traverse and clear functions of a type using thePy_TPFLAGS_MANAGED_DICT
flag. The pythoncapi-compat project can be used to use these functions with Python 3.11 and 3.12. (Contributed by Victor Stinner in gh-107073.)Add the
PyRefTracer_SetTracer()
andPyRefTracer_GetTracer()
functions, which enable tracking object creation and destruction in the same way that thetracemalloc
module does. (Contributed by Pablo Galindo in gh-93502.)Add the
PySys_AuditTuple()
function as an alternative toPySys_Audit()
that takes event arguments as a Pythontuple
object. (Contributed by Victor Stinner in gh-85283.)Add the
PyThreadState_GetUnchecked()
function as an alternative toPyThreadState_Get()
that doesn’t kill the process with a fatal error if it isNULL
. The caller is responsible for checking if the result isNULL
. (Contributed by Victor Stinner in gh-108867.)Add the
PyType_GetFullyQualifiedName()
function to get the type’s fully qualified name. The module name is prepended iftype.__module__
is a string and is not equal to either'builtins'
or'__main__'
. (Contributed by Victor Stinner in gh-111696.)Add the
PyType_GetModuleName()
function to get the type’s module name. This is equivalent to getting thetype.__module__
attribute. (Contributed by Eric Snow and Victor Stinner in gh-111696.)Add the
PyUnicode_EqualToUTF8AndSize()
andPyUnicode_EqualToUTF8()
functions to compare a Unicode object with a const char* UTF-8 encoded string and1
if they are equal or0
otherwise. These functions do not raise exceptions. (Contributed by Serhiy Storchaka in gh-110289.)Add the
PyWeakref_GetRef()
function as an alternative toPyWeakref_GetObject()
that returns a strong reference orNULL
if the referent is no longer live. (Contributed by Victor Stinner in gh-105927.)Add fixed variants of functions which silently ignore errors:
PyObject_HasAttrStringWithError()
replacesPyObject_HasAttrString()
.PyMapping_HasKeyStringWithError()
replacesPyMapping_HasKeyString()
.
The new functions return
-1
for errors and the standard1
for true and0
for false.(Contributed by Serhiy Storchaka in gh-108511.)
Changed C APIs¶
The keywords parameter of
PyArg_ParseTupleAndKeywords()
andPyArg_VaParseTupleAndKeywords()
now has type char *const* in C and const char *const* in C++, instead of char**. In C++, this makes these functions compatible with arguments of type const char *const*, const char**, or char *const* without an explicit type cast. In C, the functions only support arguments of type char *const*. This can be overridden with thePY_CXX_CONST
macro. (Contributed by Serhiy Storchaka in gh-65210.)PyArg_ParseTupleAndKeywords()
now supports non-ASCII keyword parameter names. (Contributed by Serhiy Storchaka in gh-110815.)The
PyCode_GetFirstFree()
function is now unstable API and is now namedPyUnstable_Code_GetFirstFree()
. (Contributed by Bogdan Romanyuk in gh-115781.)The
PyDict_GetItem()
,PyDict_GetItemString()
,PyMapping_HasKey()
,PyMapping_HasKeyString()
,PyObject_HasAttr()
,PyObject_HasAttrString()
, andPySys_GetObject()
functions, each of which clears all errors which occurred when calling them now reports these errors usingsys.unraisablehook()
. You may replace them with other functions as recommended in the documentation. (Contributed by Serhiy Storchaka in gh-106672.)Add support for the
%T
,%#T
,%N
and%#N
formats toPyUnicode_FromFormat()
:%T
: Get the fully qualified name of an object type%#T
: As above, but use a colon as the separator%N
: Get the fully qualified name of a type%#N
: As above, but use a colon as the separator
See PEP 737 for more information. (Contributed by Victor Stinner in gh-111696.)
You no longer have to define the
PY_SSIZE_T_CLEAN
macro before includingPython.h
when using#
formats in format codes. APIs accepting the format codes always usePy_ssize_t
for#
formats. (Contributed by Inada Naoki in gh-104922.)If Python is built in debug mode or
with assertions
,PyTuple_SET_ITEM()
andPyList_SET_ITEM()
now check the index argument with an assertion. (Contributed by Victor Stinner in gh-106168.)
Limited C API Changes¶
The following functions are now included in the Limited C API:
Python built with
--with-trace-refs
(tracing references) now supports the Limited API. (Contributed by Victor Stinner in gh-108634.)
Removed C APIs¶
Remove several functions, macros, variables, etc with names prefixed by
_Py
or_PY
(which are considered private). If your project is affected by one of these removals and you believe that the removed API should remain available, please open a new issue to request a public C API and addcc: @vstinner
to the issue to notify Victor Stinner. (Contributed by Victor Stinner in gh-106320.)Remove old buffer protocols deprecated in Python 3.0. Use Buffer Protocol instead.
PyObject_CheckReadBuffer()
: UsePyObject_CheckBuffer()
to test whether the object supports the buffer protocol. Note thatPyObject_CheckBuffer()
doesn’t guarantee thatPyObject_GetBuffer()
will succeed. To test if the object is actually readable, see the next example ofPyObject_GetBuffer()
.PyObject_AsCharBuffer()
,PyObject_AsReadBuffer()
: UsePyObject_GetBuffer()
andPyBuffer_Release()
instead:Py_buffer view; if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) { return NULL; } // Use `view.buf` and `view.len` to read from the buffer. // You may need to cast buf as `(const char*)view.buf`. PyBuffer_Release(&view);
PyObject_AsWriteBuffer()
: UsePyObject_GetBuffer()
andPyBuffer_Release()
instead:Py_buffer view; if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) { return NULL; } // Use `view.buf` and `view.len` to write to the buffer. PyBuffer_Release(&view);
(Contributed by Inada Naoki in gh-85275.)
Remove various functions deprecated in Python 3.9:
PyEval_CallObject()
,PyEval_CallObjectWithKeywords()
: UsePyObject_CallNoArgs()
orPyObject_Call()
instead.Warning
In
PyObject_Call()
, positional arguments must be atuple
and must not beNULL
, and keyword arguments must be adict
orNULL
, whereas the removed functions checked argument types and acceptedNULL
positional and keyword arguments. To replacePyEval_CallObjectWithKeywords(func, NULL, kwargs)
withPyObject_Call()
, pass an empty tuple as positional arguments usingPyTuple_New(0)
.PyEval_CallFunction()
: UsePyObject_CallFunction()
instead.PyEval_CallMethod()
: UsePyObject_CallMethod()
instead.PyCFunction_Call()
: UsePyObject_Call()
instead.
(Contributed by Victor Stinner in gh-105107.)
Remove the following old functions to configure the Python initialization, deprecated in Python 3.11:
PySys_AddWarnOptionUnicode()
: UsePyConfig.warnoptions
instead.PySys_AddWarnOption()
: UsePyConfig.warnoptions
instead.PySys_AddXOption()
: UsePyConfig.xoptions
instead.PySys_HasWarnOptions()
: UsePyConfig.xoptions
instead.PySys_SetPath()
: SetPyConfig.module_search_paths
instead.Py_SetPath()
: SetPyConfig.module_search_paths
instead.Py_SetStandardStreamEncoding()
: SetPyConfig.stdio_encoding
instead, and set also maybePyConfig.legacy_windows_stdio
(on Windows)._Py_SetProgramFullPath()
: SetPyConfig.executable
instead.
Use the new
PyConfig
API of the Python Initialization Configuration instead (PEP 587), added to Python 3.8. (Contributed by Victor Stinner in gh-105145.)Remove
PyEval_AcquireLock()
andPyEval_ReleaseLock()
functions, deprecated in Python 3.2. They didn’t update the current thread state. They can be replaced with:low-level
PyEval_AcquireThread()
andPyEval_RestoreThread()
;
(Contributed by Victor Stinner in gh-105182.)
Remove the
PyEval_ThreadsInitialized()
function, deprecated in Python 3.9. Since Python 3.7,Py_Initialize()
always creates the GIL: callingPyEval_InitThreads()
does nothing andPyEval_ThreadsInitialized()
always returns non-zero. (Contributed by Victor Stinner in gh-105182.)Remove the
_PyInterpreterState_Get()
alias toPyInterpreterState_Get()
which was kept for backward compatibility with Python 3.8. The pythoncapi-compat project can be used to getPyInterpreterState_Get()
on Python 3.8 and older. (Contributed by Victor Stinner in gh-106320.)Remove the private
_PyObject_FastCall()
function: usePyObject_Vectorcall()
which is available since Python 3.8 (PEP 590). (Contributed by Victor Stinner in gh-106023.)Remove the
cpython/pytime.h
header file, which only contained private functions. (Contributed by Victor Stinner in gh-106316.)Remove the undocumented
PY_TIMEOUT_MAX
constant from the limited C API. (Contributed by Victor Stinner in gh-110014.)Remove the old trashcan macros
Py_TRASHCAN_SAFE_BEGIN
andPy_TRASHCAN_SAFE_END
. Replace both with the new macrosPy_TRASHCAN_BEGIN
andPy_TRASHCAN_END
. (Contributed by Irit Katriel in gh-105111.)
Deprecated C APIs¶
Deprecate old Python initialization functions:
PySys_ResetWarnOptions()
: Clearsys.warnoptions
andwarnings.filters
instead.Py_GetExecPrefix()
: Getsys.exec_prefix
instead.Py_GetPath()
: Getsys.path
instead.Py_GetPrefix()
: Getsys.prefix
instead.Py_GetProgramFullPath()
: Getsys.executable
instead.Py_GetProgramName()
: Getsys.executable
instead.Py_GetPythonHome()
: GetPyConfig.home
or thePYTHONHOME
environment variable instead.
(Contributed by Victor Stinner in gh-105145.)
Soft deprecate the
PyEval_GetBuiltins()
,PyEval_GetGlobals()
, andPyEval_GetLocals()
functions, which return a borrowed reference. (Soft deprecated as part of PEP 667.)Deprecate the
PyImport_ImportModuleNoBlock()
function, which is just an alias toPyImport_ImportModule()
since Python 3.3. (Contributed by Victor Stinner in gh-105396.)Soft deprecate the
PyModule_AddObject()
function. It should be replaced withPyModule_Add()
orPyModule_AddObjectRef()
. (Contributed by Serhiy Storchaka in gh-86493.)Deprecate the old
Py_UNICODE
andPY_UNICODE_TYPE
types and thePy_UNICODE_WIDE
define. Use thewchar_t
type directly instead. Since Python 3.3,Py_UNICODE
andPY_UNICODE_TYPE
are just aliases towchar_t
. (Contributed by Victor Stinner in gh-105156.)Deprecate the
PyWeakref_GetObject()
andPyWeakref_GET_OBJECT()
functions, which return a borrowed reference. Replace them with the newPyWeakref_GetRef()
function, which returns a strong reference. The pythoncapi-compat project can be used to getPyWeakref_GetRef()
on Python 3.12 and older. (Contributed by Victor Stinner in gh-105927.)
Pending removal in Python 3.14¶
The
ma_version_tag
field inPyDictObject
for extension modules (PEP 699; gh-101193).Creating
immutable types
with mutable bases (gh-95388).
Pending removal in Python 3.15¶
The
PyImport_ImportModuleNoBlock()
: UsePyImport_ImportModule()
instead.PyWeakref_GetObject()
andPyWeakref_GET_OBJECT()
: UsePyWeakref_GetRef()
instead. The pythoncapi-compat project can be used to getPyWeakref_GetRef()
on Python 3.12 and older.Py_UNICODE
type and thePy_UNICODE_WIDE
macro: Usewchar_t
instead.PyUnicode_AsDecodedObject()
: UsePyCodec_Decode()
instead.PyUnicode_AsDecodedUnicode()
: UsePyCodec_Decode()
instead; Note that some codecs (for example, “base64”) may return a type other thanstr
, such asbytes
.PyUnicode_AsEncodedObject()
: UsePyCodec_Encode()
instead.PyUnicode_AsEncodedUnicode()
: UsePyCodec_Encode()
instead; Note that some codecs (for example, “base64”) may return a type other thanbytes
, such asstr
.Python initialization functions, deprecated in Python 3.13:
Py_GetPath()
: UsePyConfig_Get("module_search_paths")
(sys.path
) instead.Py_GetPrefix()
: UsePyConfig_Get("base_prefix")
(sys.base_prefix
) instead. UsePyConfig_Get("prefix")
(sys.prefix
) if virtual environments need to be handled.Py_GetExecPrefix()
: UsePyConfig_Get("base_exec_prefix")
(sys.base_exec_prefix
) instead. UsePyConfig_Get("exec_prefix")
(sys.exec_prefix
) if virtual environments need to be handled.Py_GetProgramFullPath()
: UsePyConfig_Get("executable")
(sys.executable
) instead.Py_GetProgramName()
: UsePyConfig_Get("executable")
(sys.executable
) instead.Py_GetPythonHome()
: UsePyConfig_Get("home")
or thePYTHONHOME
environment variable instead.
The pythoncapi-compat project can be used to get
PyConfig_Get()
on Python 3.13 and older.Functions to configure Python’s initialization, deprecated in Python 3.11:
PySys_SetArgvEx()
: SetPyConfig.argv
instead.PySys_SetArgv()
: SetPyConfig.argv
instead.Py_SetProgramName()
: SetPyConfig.program_name
instead.Py_SetPythonHome()
: SetPyConfig.home
instead.PySys_ResetWarnOptions()
: Clearsys.warnoptions
andwarnings.filters
instead.
The
Py_InitializeFromConfig()
API should be used withPyConfig
instead.Global configuration variables:
Py_DebugFlag
: UsePyConfig.parser_debug
orPyConfig_Get("parser_debug")
instead.Py_VerboseFlag
: UsePyConfig.verbose
orPyConfig_Get("verbose")
instead.Py_QuietFlag
: UsePyConfig.quiet
orPyConfig_Get("quiet")
instead.Py_InteractiveFlag
: UsePyConfig.interactive
orPyConfig_Get("interactive")
instead.Py_InspectFlag
: UsePyConfig.inspect
orPyConfig_Get("inspect")
instead.Py_OptimizeFlag
: UsePyConfig.optimization_level
orPyConfig_Get("optimization_level")
instead.Py_NoSiteFlag
: UsePyConfig.site_import
orPyConfig_Get("site_import")
instead.Py_BytesWarningFlag
: UsePyConfig.bytes_warning
orPyConfig_Get("bytes_warning")
instead.Py_FrozenFlag
: UsePyConfig.pathconfig_warnings
orPyConfig_Get("pathconfig_warnings")
instead.Py_IgnoreEnvironmentFlag
: UsePyConfig.use_environment
orPyConfig_Get("use_environment")
instead.Py_DontWriteBytecodeFlag
: UsePyConfig.write_bytecode
orPyConfig_Get("write_bytecode")
instead.Py_NoUserSiteDirectory
: UsePyConfig.user_site_directory
orPyConfig_Get("user_site_directory")
instead.Py_UnbufferedStdioFlag
: UsePyConfig.buffered_stdio
orPyConfig_Get("buffered_stdio")
instead.Py_HashRandomizationFlag
: UsePyConfig.use_hash_seed
andPyConfig.hash_seed
orPyConfig_Get("hash_seed")
instead.Py_IsolatedFlag
: UsePyConfig.isolated
orPyConfig_Get("isolated")
instead.Py_LegacyWindowsFSEncodingFlag
: UsePyPreConfig.legacy_windows_fs_encoding
orPyConfig_Get("legacy_windows_fs_encoding")
instead.Py_LegacyWindowsStdioFlag
: UsePyConfig.legacy_windows_stdio
orPyConfig_Get("legacy_windows_stdio")
instead.Py_FileSystemDefaultEncoding
,Py_HasFileSystemDefaultEncoding
: UsePyConfig.filesystem_encoding
orPyConfig_Get("filesystem_encoding")
instead.Py_FileSystemDefaultEncodeErrors
: UsePyConfig.filesystem_errors
orPyConfig_Get("filesystem_errors")
instead.Py_UTF8Mode
: UsePyPreConfig.utf8_mode
orPyConfig_Get("utf8_mode")
instead. (seePy_PreInitialize()
)
The
Py_InitializeFromConfig()
API should be used withPyConfig
to set these options. OrPyConfig_Get()
can be used to get these options at runtime.
Pending removal in Python 3.16¶
The bundled copy of
libmpdec
.
Pending removal in Python 3.18¶
The following private functions are deprecated and planned for removal in Python 3.18:
_PyBytes_Join()
: usePyBytes_Join()
._PyDict_GetItemStringWithError()
: usePyDict_GetItemStringRef()
._PyDict_Pop()
: usePyDict_Pop()
._PyLong_Sign()
: usePyLong_GetSign()
._PyLong_FromDigits()
and_PyLong_New()
: usePyLongWriter_Create()
._PyThreadState_UncheckedGet()
: usePyThreadState_GetUnchecked()
._PyUnicode_AsString()
: usePyUnicode_AsUTF8()
._PyUnicodeWriter_Init()
: replace_PyUnicodeWriter_Init(&writer)
withwriter = PyUnicodeWriter_Create(0)
._PyUnicodeWriter_Finish()
: replace_PyUnicodeWriter_Finish(&writer)
withPyUnicodeWriter_Finish(writer)
._PyUnicodeWriter_Dealloc()
: replace_PyUnicodeWriter_Dealloc(&writer)
withPyUnicodeWriter_Discard(writer)
._PyUnicodeWriter_WriteChar()
: replace_PyUnicodeWriter_WriteChar(&writer, ch)
withPyUnicodeWriter_WriteChar(writer, ch)
._PyUnicodeWriter_WriteStr()
: replace_PyUnicodeWriter_WriteStr(&writer, str)
withPyUnicodeWriter_WriteStr(writer, str)
._PyUnicodeWriter_WriteSubstring()
: replace_PyUnicodeWriter_WriteSubstring(&writer, str, start, end)
withPyUnicodeWriter_WriteSubstring(writer, str, start, end)
._PyUnicodeWriter_WriteASCIIString()
: replace_PyUnicodeWriter_WriteASCIIString(&writer, str)
withPyUnicodeWriter_WriteASCII(writer, str)
._PyUnicodeWriter_WriteLatin1String()
: replace_PyUnicodeWriter_WriteLatin1String(&writer, str)
withPyUnicodeWriter_WriteUTF8(writer, str)
._PyUnicodeWriter_Prepare()
: (no replacement)._PyUnicodeWriter_PrepareKind()
: (no replacement)._Py_HashPointer()
: usePy_HashPointer()
._Py_fopen_obj()
: usePy_fopen()
.
The pythoncapi-compat project can be used to get these new public functions on Python 3.13 and older. (Contributed by Victor Stinner in gh-128863.)
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()
: UsePyErr_GetRaisedException()
instead.PyErr_NormalizeException()
: UsePyErr_GetRaisedException()
instead.PyErr_Restore()
: UsePyErr_SetRaisedException()
instead.PyModule_GetFilename()
: UsePyModule_GetFilenameObject()
instead.PyOS_AfterFork()
: UsePyOS_AfterFork_Child()
instead.PySlice_GetIndicesEx()
: UsePySlice_Unpack()
andPySlice_AdjustIndices()
instead.PyUnicode_READY()
: Unneeded since Python 3.12PyErr_Display()
: UsePyErr_DisplayException()
instead._PyErr_ChainExceptions()
: Use_PyErr_ChainExceptions1()
instead.PyBytesObject.ob_shash
member: callPyObject_Hash()
instead.Thread Local Storage (TLS) API:
PyThread_create_key()
: UsePyThread_tss_alloc()
instead.PyThread_delete_key()
: UsePyThread_tss_free()
instead.PyThread_set_key_value()
: UsePyThread_tss_set()
instead.PyThread_get_key_value()
: UsePyThread_tss_get()
instead.PyThread_delete_key_value()
: UsePyThread_tss_delete()
instead.PyThread_ReInitTLS()
: Unneeded since Python 3.7.
Build Changes¶
arm64-apple-ios
andarm64-apple-ios-simulator
are both now PEP 11 tier 3 platforms. (PEP 730 written and implementation contributed by Russell Keith-Magee in gh-114099.)aarch64-linux-android
andx86_64-linux-android
are both now PEP 11 tier 3 platforms. (PEP 738 written and implementation contributed by Malcolm Smith in gh-116622.)wasm32-wasi
is now a PEP 11 tier 2 platform. (Contributed by Brett Cannon in gh-115192.)wasm32-emscripten
is no longer a PEP 11 supported platform. (Contributed by Brett Cannon in gh-115192.)Building CPython now requires a compiler with support for the C11 atomic library, GCC built-in atomic functions, or MSVC interlocked intrinsics.
Autoconf 2.71 and aclocal 1.16.5 are now required to regenerate the
configure
script. (Contributed by Christian Heimes in gh-89886 and by Victor Stinner in gh-112090.)SQLite 3.15.2 or newer is required to build the
sqlite3
extension module. (Contributed by Erlend Aasland in gh-105875.)CPython now bundles the mimalloc library by default. It is licensed under the MIT license; see mimalloc license. The bundled mimalloc has custom changes, see gh-113141 for details. (Contributed by Dino Viehland in gh-109914.)
The
configure
option--with-system-libmpdec
now defaults toyes
. The bundled copy oflibmpdec
will be removed in Python 3.16.Python built with
configure
--with-trace-refs
(tracing references) is now ABI compatible with the Python release build and debug build. (Contributed by Victor Stinner in gh-108634.)On POSIX systems, the pkg-config (
.pc
) filenames now include the ABI flags. For example, the free-threaded build generatespython-3.13t.pc
and the debug build generatespython-3.13d.pc
.The
errno
,fcntl
,grp
,md5
,pwd
,resource
,termios
,winsound
,_ctypes_test
,_multiprocessing.posixshmem
,_scproxy
,_stat
,_statistics
,_testconsole
,_testimportmultiple
and_uuid
C extensions are now built with the limited C API. (Contributed by Victor Stinner in gh-85283.)
Porting to Python 3.13¶
This section lists previously described changes and other bugfixes that may require changes to your code.
Changes in the Python API¶
PEP 667 introduces several changes to the semantics of
locals()
andf_locals
:Calling
locals()
in an optimized scope now produces an independent snapshot on each call, and hence no longer implicitly updates previously returned references. Obtaining the legacy CPython behavior now requires explicit calls to update the initially returned dictionary with the results of subsequent calls tolocals()
. Code execution functions that implicitly targetlocals()
(such asexec
andeval
) must be passed an explicit namespace to access their results in an optimized scope. (Changed as part of PEP 667.)Calling
locals()
from a comprehension at module or class scope (including viaexec
oreval
) once more behaves as if the comprehension were running as an independent nested function (i.e. the local variables from the containing scope are not included). In Python 3.12, this had changed to include the local variables from the containing scope when implementing PEP 709. (Changed as part of PEP 667.)Accessing
FrameType.f_locals
in an optimized scope now returns a write-through proxy rather than a snapshot that gets updated at ill-specified times. If a snapshot is desired, it must be created explicitly withdict
or the proxy’s.copy()
method. (Changed as part of PEP 667.)
functools.partial
now emits aFutureWarning
when used as a method. The behavior will change in future Python versions. Wrap it instaticmethod()
if you want to preserve the old behavior. (Contributed by Serhiy Storchaka in gh-121027.)An
OSError
is now raised bygetpass.getuser()
for any failure to retrieve a username, instead ofImportError
on non-Unix platforms orKeyError
on Unix platforms where the password database is empty.The value of the
mode
attribute ofgzip.GzipFile
is now a string ('rb'
or'wb'
) instead of an integer (1
or2
). The value of themode
attribute of the readable file-like object returned byzipfile.ZipFile.open()
is now'rb'
instead of'r'
. (Contributed by Serhiy Storchaka in gh-115961.)mailbox.Maildir
now ignores files with a leading dot (.
). (Contributed by Zackery Spytz in gh-65559.)pathlib.Path.glob()
andrglob()
now return both files and directories if a pattern that ends with “**
” is given, rather than directories only. Add a trailing slash to keep the previous behavior and only match directories.The
threading
module now expects the_thread
module to have an_is_main_interpreter()
function. This function takes no arguments and returnsTrue
if the current interpreter is the main interpreter.Any library or application that provides a custom
_thread
module must provide_is_main_interpreter()
, just like the module’s other “private” attributes. (gh-112826.)
Changes in the C API¶
Python.h
no longer includes the<ieeefp.h>
standard header. It was included for thefinite()
function which is now provided by the<math.h>
header. It should now be included explicitly if needed. Remove also theHAVE_IEEEFP_H
macro. (Contributed by Victor Stinner in gh-108765.)Python.h
no longer includes these standard header files:<time.h>
,<sys/select.h>
and<sys/time.h>
. If needed, they should now be included explicitly. For example,<time.h>
provides theclock()
andgmtime()
functions,<sys/select.h>
provides theselect()
function, and<sys/time.h>
provides thefutimes()
,gettimeofday()
andsetitimer()
functions. (Contributed by Victor Stinner in gh-108765.)On Windows,
Python.h
no longer includes the<stddef.h>
standard header file. If needed, it should now be included explicitly. For example, it providesoffsetof()
function, andsize_t
andptrdiff_t
types. Including<stddef.h>
explicitly was already needed by all other platforms, theHAVE_STDDEF_H
macro is only defined on Windows. (Contributed by Victor Stinner in gh-108765.)If the
Py_LIMITED_API
macro is defined,Py_BUILD_CORE
,Py_BUILD_CORE_BUILTIN
andPy_BUILD_CORE_MODULE
macros are now undefined by<Python.h>
. (Contributed by Victor Stinner in gh-85283.)The old trashcan macros
Py_TRASHCAN_SAFE_BEGIN
andPy_TRASHCAN_SAFE_END
were removed. They should be replaced by the new macrosPy_TRASHCAN_BEGIN
andPy_TRASHCAN_END
.A
tp_dealloc
function that has the old macros, such as:static void mytype_dealloc(mytype *p) { PyObject_GC_UnTrack(p); Py_TRASHCAN_SAFE_BEGIN(p); ... Py_TRASHCAN_SAFE_END }
should migrate to the new macros as follows:
static void mytype_dealloc(mytype *p) { PyObject_GC_UnTrack(p); Py_TRASHCAN_BEGIN(p, mytype_dealloc) ... Py_TRASHCAN_END }
Note that
Py_TRASHCAN_BEGIN
has a second argument which should be the deallocation function it is in. The new macros were added in Python 3.8 and the old macros were deprecated in Python 3.11. (Contributed by Irit Katriel in gh-105111.)
PEP 667 introduces several changes to frame-related functions:
The effects of mutating the dictionary returned from
PyEval_GetLocals()
in an optimized scope have changed. New dict entries added this way will now only be visible to subsequentPyEval_GetLocals()
calls in that frame, asPyFrame_GetLocals()
,locals()
, andFrameType.f_locals
no longer access the same underlying cached dictionary. Changes made to entries for actual variable names and names added via the write-through proxy interfaces will be overwritten on subsequent calls toPyEval_GetLocals()
in that frame. The recommended code update depends on how the function was being used, so refer to the deprecation notice on the function for details.Calling
PyFrame_GetLocals()
in an optimized scope now returns a write-through proxy rather than a snapshot that gets updated at ill-specified times. If a snapshot is desired, it must be created explicitly (e.g. withPyDict_Copy()
), or by calling the newPyEval_GetFrameLocals()
API.PyFrame_FastToLocals()
andPyFrame_FastToLocalsWithError()
no longer have any effect. Calling these functions has been redundant since Python 3.11, whenPyFrame_GetLocals()
was first introduced.PyFrame_LocalsToFast()
no longer has any effect. Calling this function is redundant now thatPyFrame_GetLocals()
returns a write-through proxy for optimized scopes.
Python 3.13 removed many private functions. Some of them can be replaced using these alternatives:
_PyDict_Pop()
:PyDict_Pop()
orPyDict_PopString()
;_PyDict_GetItemWithError()
:PyDict_GetItemRef()
;_PyErr_WriteUnraisableMsg()
:PyErr_FormatUnraisable()
;_PyEval_SetTrace()
:PyEval_SetTrace()
orPyEval_SetTraceAllThreads()
;_PyList_Extend()
:PyList_Extend()
;_PyLong_AsInt()
:PyLong_AsInt()
;_PyMem_RawStrdup()
:strdup()
;_PyMem_Strdup()
:strdup()
;_PyObject_ClearManagedDict()
:PyObject_ClearManagedDict()
;_PyObject_VisitManagedDict()
:PyObject_VisitManagedDict()
;_PyThreadState_UncheckedGet()
:PyThreadState_GetUnchecked()
;_PyTime_AsSecondsDouble()
:PyTime_AsSecondsDouble()
;_PyTime_GetMonotonicClock()
:PyTime_Monotonic()
orPyTime_MonotonicRaw()
;_PyTime_GetPerfCounter()
:PyTime_PerfCounter()
orPyTime_PerfCounterRaw()
;_PyTime_GetSystemClock()
:PyTime_Time()
orPyTime_TimeRaw()
;_PyTime_MAX
:PyTime_MAX
;_PyTime_MIN
:PyTime_MIN
;_PyTime_t
:PyTime_t
;_Py_HashPointer()
:Py_HashPointer()
;_Py_IsFinalizing()
:Py_IsFinalizing()
.
The pythoncapi-compat project can be used to get most of these new functions on Python 3.12 and older.
Regression Test Changes¶
Python built with
configure
--with-pydebug
now supports a-X presite=package.module
command-line option. If used, it specifies a module that should be imported early in the lifecycle of the interpreter, beforesite.py
is executed. (Contributed by Łukasz Langa in gh-110769.)