A better interactive interpreter¶

Python now uses a newinteractive shell by default, based on codefrom thePyPy project.When the user starts theREPL from an interactive terminal,the following new features are now supported:

• Multiline editing with history preservation.

• Direct support for REPL-specific commands likehelp,exit,andquit, without the need to call them as functions.

• Prompts and tracebacks withcolor enabled by default.

• Interactive help browsing usingF1 with a separate commandhistory.

• History browsing usingF2 that skips output as well as the>>> and… prompts.

• “Paste mode” withF3 that makes pasting larger blocks of codeeasier (pressF3 again to return to the regular prompt).

To disable the new interactive shell,set thePYTHON_BASIC_REPL environment variable.For more on interactive mode, seeInteractive Mode.

(Contributed by Pablo Galindo Salgado, Łukasz Langa, andLysandros Nikolaou ingh-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 theterminal. This featurecan be controlledvia the newPYTHON_COLORS environment variable as well asthe canonicalNO_COLOR andFORCE_COLOR environment variables.(Contributed by Pablo Galindo Salgado ingh-112730.)

• A common mistake is to write a script with the same name as astandard library module. When this results in errors, we nowdisplay a more helpful error message:

  $ python random.pyTraceback (most recent call last):  File"/home/me/random.py", line1, in<module>importrandom  File"/home/me/random.py", line3, 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-partymodule that it attempts to import and this results in errors,we also display a more helpful error message:

  $ python numpy.pyTraceback (most recent call last):  File"/home/me/numpy.py", line1, in<module>importnumpyasnp  File"/home/me/numpy.py", line3, 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 ingh-95754.)

• The error message now tries to suggest the correct keyword argumentwhen 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>", line1, 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 ingh-107944.)

Free-threaded CPython¶

CPython now has experimental support for running in a free-threaded mode,with theglobal 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 calledpython3.13t orpython3.13t.exe.Pre-built binaries marked asfree-threaded can be installed as part ofthe officialWindowsandmacOS installers,or CPython can be built from source with the--disable-gil option.

Free-threaded execution allows for full utilization of the availableprocessing power by running threads in parallel on available CPU cores.While not all software will benefit from this automatically, programsdesigned 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 GILenabled at runtime using the environment variablePYTHON_GIL orthe command-line option-Xgil=1.

To check if the current interpreter supports free-threading,python-VVandsys.version contain “experimental free-threading build”.The newsys._is_gil_enabled() function can be used to check whetherthe GIL is actually disabled in the running process.

C-API extension modules need to be built specifically for the free-threadedbuild. Extensions that support running with theGIL disabled shoulduse thePy_mod_gil slot. Extensions using single-phase init shouldusePyUnstable_Module_SetGIL() to indicate whether they supportrunning with the GIL disabled. Importing C extensions that don’t use thesemechanisms will cause the GIL to be enabled, unless the GIL was explicitlydisabled with thePYTHON_GIL environment variable or the-Xgil=0 option.pip 24.1 or newer is required to install packages with C extensions in thefree-threaded build.

This work was made possible thanks to many individuals andorganizations, including the large community of contributors to Pythonand 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 hasprovided significant engineering resources to support this project.

An experimental just-in-time (JIT) compiler¶

When CPython is configured and built usingthe--enable-experimental-jit option,a just-in-time (JIT) compiler is added which may speed up some Python programs.On Windows, usePCbuild/build.bat--experimental-jit to enable the JITor--experimental-jit-interpreter to enable the Tier 2 interpreter.Build requirements and further supporting informationare contained atTools/jit/README.md.

The--enable-experimental-jit option takes these (optional) values,defaulting toyes if--enable-experimental-jit is presentwithout 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 specializedTier 1 bytecode.SeeWhat’s new in 3.11 for details.

• When the Tier 1 bytecode gets hot enough, it gets translatedto a new purely internal intermediate representation (IR),called theTier 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 appliedbefore it is interpreted or translated to machine code.

• There is a Tier 2 interpreter, but it is mostly intended for debuggingthe earlier stages of the optimization pipeline.The Tier 2 interpreter can be enabled by configuring Pythonwith--enable-experimental-jit=interpreter.

• When the JIT is enabled, the optimizedTier 2 IR is translated to machine code, which is then executed.

• The machine code translation process uses a technique calledcopy-and-patch. It has no runtime dependencies, but there is a newbuild-time dependency on LLVM.

(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 forlocals()¶

Historically, the expected result of mutating the return value oflocals() has been left to individual Python implementations to define.Starting from Python 3.13,PEP 667 standardisesthe historical behavior of CPython for most code execution scopes,but changesoptimized scopes(functions, generators, coroutines, comprehensions, and generator expressions)to explicitly return independent snapshots of the currently assigned localvariables, including locally referenced nonlocal variables captured in closures.

This change to the semantics oflocals() in optimized scopes alsoaffects the default behavior of code execution functions that implicitlytargetlocals() if no explicit namespace is provided(such asexec() andeval()).In previous versions, whether or not changes could be accessed by callinglocals() after calling the code execution function wasimplementation-dependent. In CPython specifically, such code would typicallyappear to work as desired, but could sometimes fail in optimized scopes basedon 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 ofthe local variables in optimized scopes, and hence the changes will neverbe visible in subsequent calls tolocals().To access the changes made in these cases, an explicit namespace referencemust now be passed to the relevant function.Alternatively, it may make sense to update affected code to use a higher levelcode 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 inscopes affected by this change,FrameType.f_locals nowreturns a write-through proxy to the frame’s local and locally referencednonlocal variables in these scopes, rather than returning an inconsistentlyupdated shareddict instance with undefined runtime semantics.

SeePEP 667 for more details, including related C API changesand deprecations. Porting notes are also provided below for the affectedPython APIs andC APIs.

(PEP and implementation contributed by Mark Shannon and Tian Gao ingh-74929. Documentation updates provided by Guido van Rossum andAlyssa Coghlan.)

Support for mobile platforms¶

PEP 730: iOS is now aPEP 11 supported platform, with thearm64-apple-ios andarm64-apple-ios-simulator targets at tier 3(iPhone and iPad devices released after 2013 and the Xcode iOS simulatorrunning on Apple silicon hardware, respectively).x86_64-apple-ios-simulator(the Xcode iOS simulator running on olderx86_64 hardware)is not a tier 3 supported platform, but will have best-effort support.(PEP written and implementation contributed by Russell Keith-Magee ingh-114099.)

PEP 738: Android is now aPEP 11 supported platform, with theaarch64-linux-android andx86_64-linux-android targets at tier 3.The 32-bit targetsarm-linux-androideabi andi686-linux-androidare not tier 3 supported platforms, but will have best-effort support.(PEP written and implementation contributed by Malcolm Smith ingh-116622.)

argparse¶

• Add thedeprecated parameter to theadd_argument()andadd_parser() methods, to enable deprecatingcommand-line options, positional arguments, and subcommands.(Contributed by Serhiy Storchaka ingh-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 ingh-80480.)

• Registerarray.array as aMutableSequenceby implementing theclear() method.(Contributed by Mike Zimin ingh-114894.)

ast¶

• The constructors of node types in theast module are nowstricter 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 whenconstructing an instance, the field will now be set toNone. 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 newlyconstructed AST node instance.)

  In all other cases, where a required argument is omitted,the node constructor will emit aDeprecationWarning.This will raise an exception in Python 3.15.Similarly, passing a keyword argument to the constructorthat 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 ofast.ASTunless the class opts in to the new behaviorby defining theAST._field_types mapping.

  (Contributed by Jelle Zijlstra ingh-105858,gh-117486, andgh-118851.)

• ast.parse() now accepts an optional argumentoptimizewhich is passed on tocompile().This makes it possible to obtain an optimized AST.(Contributed by Irit Katriel ingh-108113.)

asyncio¶

• asyncio.as_completed() now returns an object that is both anasynchronous iterator and a plainiteratorofawaitables.The awaitables yielded by asynchronous iteration include original taskor future objects that were passed in,making it easier to associate results with the tasks being completed.(Contributed by Justin Arthur ingh-77714.)

• asyncio.loop.create_unix_server() will now automatically removethe Unix socket when the server is closed.(Contributed by Pierre Ossman ingh-111246.)

• DatagramTransport.sendto() will now send zero-lengthdatagrams if called with an empty bytes object.The transport flow control also now accounts for the datagram headerwhen calculating the buffer size.(Contributed by Jamie Phan ingh-115199.)

• AddQueue.shutdownandQueueShutDown to manage queue termination.(Contributed by Laurie Opperman and Yves Duprat ingh-104228.)

• Add theServer.close_clients() andServer.abort_clients()methods, which more forcefully close an asyncio server.(Contributed by Pierre Ossman ingh-113538.)

• Accept a tuple of separators inStreamReader.readuntil(),stopping when any one of them is encountered.(Contributed by Bruce Merry ingh-81322.)

• Improve the behavior ofTaskGroup whenan external cancellation collides with an internal cancellation.For example, when two task groups are nestedand 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 externallyand also must raise anExceptionGroup,it will now call the parent task’scancel() method.This ensures that aCancelledError will be raisedat the nextawait, so the cancellation is not lost.

  An added benefit of these changes is that task groups now preservethe cancellation count (cancelling()).

  In order to handle some corner cases,uncancel() may nowreset the undocumented_must_cancel flagwhen the cancellation count reaches zero.

  (Inspired by an issue reported by Arthur Tacca ingh-116720.)

• WhenTaskGroup.create_task() is called on an inactiveTaskGroup, the given coroutine will be closed (whichprevents aRuntimeWarning about the given coroutine beingnever awaited).(Contributed by Arthur Tacca and Jason Zhang ingh-115957.)

• The function and methods namedcreate_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 honoredonce again (until 3.14).To keep the workarounds working, the extra**kwargs argument stillallows passing additional keyword arguments toTaskand 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 ingh-128307.)

base64¶

• Addz85encode() andz85decode() functionsfor encodingbytes asZ85 dataand decoding Z85-encoded data tobytes.(Contributed by Matan Perelman ingh-75299.)

compileall¶

• The default number of worker threads and processes is now selected usingos.process_cpu_count() instead ofos.cpu_count().(Contributed by Victor Stinner ingh-109649.)

concurrent.futures¶

• The default number of worker threads and processes is now selected usingos.process_cpu_count() instead ofos.cpu_count().(Contributed by Victor Stinner ingh-109649.)

configparser¶

• ConfigParser now has support for unnamed sections,which allows for top-level key-value pairs.This can be enabled with the newallow_unnamed_section parameter.(Contributed by Pedro Sousa Lacerda ingh-66449.)

copy¶

• The newreplace() function and thereplaceprotocol make creating modified copies of objects much simpler.This is especially useful when working with immutable objects.The following types support thereplace() functionand implement the replace protocol:

  • collections.namedtuple()

  • dataclasses.dataclass

  • datetime.datetime,datetime.date,datetime.time

  • inspect.Signature,inspect.Parameter

  • types.SimpleNamespace

  • code objects

  Any user-defined class can also supportcopy.replace() by definingthe__replace__() method.(Contributed by Serhiy Storchaka ingh-108751.)

ctypes¶

• As a consequence of necessary internal refactoring, initialization ofinternal metaclasses now happens in__init__ ratherthan in__new__. This affects projects that subclass these internalmetaclasses 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.

  Seegh-124520 for discussion and links to changes in some affectedprojects.

• ctypes.Structure objects have a new_align_attribute which allows the alignment of the structure being packed to/frommemory to be specified explicitly.(Contributed by Matt Sanderson ingh-112433)

dbm¶

• Adddbm.sqlite3, a new module which implements an SQLite backend,and make it the defaultdbm backend.(Contributed by Raymond Hettinger and Erlend E. Aasland ingh-100414.)

• Allow removing all items from the database throughthe newclear() methods of the GDBM and NDBM database objects.(Contributed by Donghee Na ingh-107122.)

dis¶

• Change the output ofdis module functions to show logicallabels for jump targets and exception handlers, rather than offsets.The offsets can be added with the new-O command-line optionor theshow_offsets argument.(Contributed by Irit Katriel ingh-112137.)

• get_instructions() no longer represents cache entriesas separate instructions.Instead, it returns them as part of theInstruction,in the newcache_info field.Theshow_caches argument toget_instructions() is deprecatedand no longer has any effect.(Contributed by Irit Katriel ingh-112962.)

doctest¶

• doctest output is now colored by default.This can be controlled via the newPYTHON_COLORS environmentvariable as well as the canonicalNO_COLORandFORCE_COLOR environment variables.See alsoControlling color.(Contributed by Hugo van Kemenade ingh-117225.)

• TheDocTestRunner.run() method now counts the number of skipped tests.Add theDocTestRunner.skips andTestResults.skipped attributes.(Contributed by Victor Stinner ingh-108794.)

email¶

• Headers with embedded newlines are now quoted on output.Thegenerator will now refuse to serialize (write) headersthat are improperly folded or delimited, such that they would be parsed asmultiple 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 ingh-121650.)

• getaddresses() andparseaddr() nowreturn('','') pairs in more situations where invalid email addressesare encountered instead of potentially inaccurate values.The two functions have a new optionalstrict parameter (defaultTrue).To get the old behavior (accepting malformed input), usestrict=False.getattr(email.utils,'supports_strict_parsing',False) can be usedto check if thestrict parameter is available.(Contributed by Thomas Dwyer and Victor Stinner forgh-102988 to improvetheCVE 2023-27043 fix.)

enum¶

• EnumDict has been made public to better support subclassingEnumType.

fractions¶

• Fraction objects now support the standardformat specification mini-language rulesfor fill, alignment, sign handling, minimum width, and grouping.(Contributed by Mark Dickinson ingh-111320.)

glob¶

• Addtranslate(), a function to convert a path specificationwith shell-style wildcards to a regular expression.(Contributed by Barney Gale ingh-72904.)

importlib¶

• The following functions inimportlib.resources now allow accessinga directory (or tree) of resources, using multiple positional arguments(theencoding anderrors arguments in the text-reading functionsare now keyword-only):

  • is_resource()

  • open_binary()

  • open_text()

  • path()

  • read_binary()

  • read_text()

  These functions are no longer deprecated and are not scheduled for removal.(Contributed by Petr Viktorin ingh-116608.)

• contents() remains deprecated in favor ofthe fully-featuredTraversable API.However, there is now no plan to remove it.(Contributed by Petr Viktorin ingh-116608.)

io¶

• TheIOBase finalizer now logs any errors raised bytheclose() method withsys.unraisablehook.Previously, errors were ignored silently by default,and only logged inPython Development Modeor when using aPython debug build.(Contributed by Victor Stinner ingh-62948.)

ipaddress¶

• Add theIPv4Address.ipv6_mapped property,which returns the IPv4-mapped IPv6 address.(Contributed by Charles Machalow ingh-109466.)

• Fixis_global andis_private behavior inIPv4Address,IPv6Address,IPv4Network, andIPv6Network.(Contributed by Jakub Stasiak ingh-113171.)

itertools¶

• batched() has a newstrict parameter,which raises aValueError if the final batch is shorterthan the specified batch size.(Contributed by Raymond Hettinger ingh-113202.)

marshal¶

• Add theallow_code parameter in module functions.Passingallow_code=False prevents serialization and de-serializationof code objects which are incompatible between Python versions.(Contributed by Serhiy Storchaka ingh-113626.)

math¶

• The new functionfma() 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” operationfor special cases.(Contributed by Mark Dickinson and Victor Stinner ingh-73468.)

mimetypes¶

• Add theguess_file_type() function to guess a MIME typefrom a filesystem path.Using paths withguess_type() is nowsoft deprecated.(Contributed by Serhiy Storchaka ingh-66543.)

mmap¶

• mmap is now protected from crashing on Windows when themapped memory is inaccessible due to file system errors or access violations.(Contributed by Jannis Weigend ingh-118209.)

• mmap has a newseekable() methodthat 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 ingh-111835.)

• The new UNIX-onlytrackfd parameter formmap controlsfile descriptor duplication;if false, the file descriptor specified byfileno will not be duplicated.(Contributed by Zackery Spytz and Petr Viktorin ingh-78502.)

multiprocessing¶

• The default number of worker threads and processes is now selected usingos.process_cpu_count() instead ofos.cpu_count().(Contributed by Victor Stinner ingh-109649.)

os¶

• Addprocess_cpu_count() function to get the numberof logical CPU cores usable by the calling thread of the current process.(Contributed by Victor Stinner ingh-109649.)

• cpu_count() andprocess_cpu_count() can be overriddenthrough the new environment variablePYTHON_CPU_COUNTor the new command-line option-Xcpu_count.This option is useful for users who need to limit CPU resourcesof a container system without having to modify application codeor the container itself.(Contributed by Donghee Na ingh-109595.)

• Add alow level interface to Linux’stimer file descriptorsviatimerfd_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 ingh-108277.)

• lchmod() and thefollow_symlinks argument ofchmod()are both now available on Windows.Note that the default value offollow_symlinksinlchmod() isFalse on Windows.(Contributed by Serhiy Storchaka ingh-59616.)

• fchmod() and support for file descriptors inchmod()are both now available on Windows.(Contributed by Serhiy Storchaka ingh-113191.)

• On Windows,mkdir() andmakedirs() now support passingamode value of0o700 to apply access control to the new directory.This implicitly affectstempfile.mkdtemp()and is a mitigation forCVE 2024-4030.Other values formode continue to be ignored.(Contributed by Steve Dower ingh-118486.)

• posix_spawn() now acceptsNone for theenv argument,which makes the newly spawned process use the current process environment.(Contributed by Jakub Kulik ingh-113119.)

• posix_spawn() can now use thePOSIX_SPAWN_CLOSEFROMattribute in thefile_actions parameter on platforms that supportposix_spawn_file_actions_addclosefrom_np().(Contributed by Jakub Kulik ingh-113117.)

os.path¶

• Addisreserved() to check if a path is reservedon the current system.This function is only available on Windows.(Contributed by Barney Gale ingh-88569.)

• On Windows,isabs() no longer considers pathsstarting with exactly one slash (\ or/) to be absolute.(Contributed by Barney Gale and Jon Foster ingh-44626.)

• realpath() now resolves MS-DOS style file nameseven if the file is not accessible.(Contributed by Moonsik Park ingh-82367.)

pathlib¶

• AddUnsupportedOperation, which is raised instead ofNotImplementedError when a path operation isn’t supported.(Contributed by Barney Gale ingh-89812.)

• Add a new constructor for creatingPath objectsfrom ‘file’ URIs (file:///),Path.from_uri().(Contributed by Barney Gale ingh-107465.)

• AddPurePath.full_match() for matching paths withshell-style wildcards, including the recursive wildcard “**”.(Contributed by Barney Gale ingh-73435.)

• Add thePurePath.parser class attribute to store theimplementation ofos.path usedfor low-level path parsing and joining.This will be eitherposixpath orntpath.

• Addrecurse_symlinks keyword-only argument toPath.glob() andrglob().(Contributed by Barney Gale ingh-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 ingh-70303.)

• Add thefollow_symlinks keyword-only argument toPath.is_file,Path.is_dir,Path.owner(), andPath.group().(Contributed by Barney Gale ingh-105793 and Kamil Turek ingh-107962.)

pdb¶

• breakpoint() andset_trace() now enter the debugger immediatelyrather than on the next line of code to be executed. This change prevents thedebugger from breaking outside of the context whenbreakpoint() is positionedat the end of the context.(Contributed by Tian Gao ingh-118579.)

• sys.path[0] is no longer replaced by the directory of the scriptbeing debugged whensys.flags.safe_path is set.(Contributed by Tian Gao and Christian Walther ingh-111762.)

• zipapp is now supported as a debugging target.(Contributed by Tian Gao ingh-118501.)

• Add ability to move between chained exceptions duringpost-mortem debugging inpm() usingthe newexceptions[exc_number] command for Pdb.(Contributed by Matthias Bussonnier ingh-106676.)

• Expressions and statements whose prefix is a pdb command are now correctlyidentified and executed.(Contributed by Tian Gao ingh-108464.)

queue¶

• AddQueue.shutdown andShutDownto manage queue termination.(Contributed by Laurie Opperman and Yves Duprat ingh-104750.)

random¶

• Add acommand-line interface.(Contributed by Hugo van Kemenade ingh-118131.)

re¶

• Renamere.error toPatternError for improved clarity.re.error is kept for backward compatibility.

shutil¶

• Support thedir_fd andfollow_symlinks keyword argumentsinchown().(Contributed by Berker Peksag and Tahia K ingh-62308)

site¶

• .pth files are now decoded using UTF-8 first,and then with thelocale encoding if UTF-8 decoding fails.(Contributed by Inada Naoki ingh-117802.)

sqlite3¶

• AResourceWarning is now emitted if aConnectionobject is notclosed explicitly.(Contributed by Erlend E. Aasland ingh-105539.)

• Add thefilter keyword-only parameter toConnection.iterdump()for filtering database objects to dump.(Contributed by Mariusz Felisiak ingh-91602.)

ssl¶

• Thecreate_default_context() API now includesVERIFY_X509_PARTIAL_CHAIN andVERIFY_X509_STRICTin its default flags.

  Note

  VERIFY_X509_STRICT may reject pre-RFC 5280or malformed certificates that the underlying OpenSSL implementationmight otherwise accept.Whilst disabling this is not recommended, you can do so using:

  importsslctx=ssl.create_default_context()ctx.verify_flags&=~ssl.VERIFY_X509_STRICT

  (Contributed by William Woodruff ingh-112389.)

statistics¶

• Addkde() for kernel density estimation.This makes it possible to estimate a continuous probability density functionfrom a fixed number of discrete samples.(Contributed by Raymond Hettinger ingh-115863.)

• Addkde_random() for sampling from anestimated probability density function created bykde().(Contributed by Raymond Hettinger ingh-115863.)

subprocess¶

• Thesubprocess module now uses theposix_spawn() function inmore situations.

  Notably, whenclose_fds isTrue (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 existingLinuxvfork() based code.

  A private control knobsubprocess._USE_POSIX_SPAWN canbe set toFalse if you need to forcesubprocessto never useposix_spawn().Please report your reason and platform details intheissue tracker if you set thisso that we can improve our API selection logic for everyone.(Contributed by Jakub Kulik ingh-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 ingh-78573.)

tempfile¶

• On Windows, the default mode0o700 used bytempfile.mkdtemp() nowlimits access to the new directory due to changes toos.mkdir().This is a mitigation forCVE 2024-4030.(Contributed by Steve Dower ingh-118486.)

time¶

• On Windows,monotonic() now uses theQueryPerformanceCounter() clock for a resolution of 1 microsecond,instead of theGetTickCount64() clock which hasa resolution of 15.6 milliseconds.(Contributed by Victor Stinner ingh-88494.)

• On Windows,time() now uses theGetSystemTimePreciseAsFileTime() clock for a resolution of 1 microsecond,instead of theGetSystemTimeAsFileTime() clock which hasa resolution of 15.6 milliseconds.(Contributed by Victor Stinner ingh-63207.)

tkinter¶

• Addtkinter 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 ingh-72684.)

• Thetkinter widget methodwm_attributes() now acceptsthe 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 ingh-43457.)

• wm_attributes() can now return attributes as adict,by using the new optional keyword-only parameterreturn_python_dict.(Contributed by Serhiy Storchaka ingh-43457.)

• Text.count() can now return a simpleintwhen the new optional keyword-only parameterreturn_ints is used.Otherwise, the single count is returned as a 1-tuple orNone.(Contributed by Serhiy Storchaka ingh-97928.)

• Support the “vsapi” element type intheelement_create() method oftkinter.ttk.Style.(Contributed by Serhiy Storchaka ingh-68166.)

• Add theafter_info() method for Tkinter widgets.(Contributed by Cheryl Sabella ingh-77020.)

• Add a newcopy_replace() method toPhotoImageto copy a region from one image to another,possibly with pixel zooming, subsampling, or both.(Contributed by Serhiy Storchaka ingh-118225.)

• Addfrom_coords parameter to thePhotoImage methodscopy(),zoom() andsubsample().Addzoom andsubsample parameters to thePhotoImage methodcopy().(Contributed by Serhiy Storchaka ingh-118225.)

• Add thePhotoImage methodsread() to read an image from a fileanddata() to get the image data.Addbackground andgrayscale parameters to thewrite() method.(Contributed by Serhiy Storchaka ingh-118271.)

traceback¶

• Add theexc_type_str attributetoTracebackException,which holds a string display of theexc_type.Deprecate theexc_type attribute,which holds the type object itself.Add parametersave_exc_type (defaultTrue)to indicate whetherexc_type should be saved.(Contributed by Irit Katriel ingh-112332.)

• Add a newshow_group keyword-only parameter toTracebackException.format_exception_only() to (recursively) formatthe nested exceptions of aBaseExceptionGroup instance.(Contributed by Irit Katriel ingh-105292.)

types¶

• SimpleNamespace can now take a single positional argumentto initialise the namespace’s arguments.This argument must either be a mapping or an iterable of key-value pairs.(Contributed by Serhiy Storchaka ingh-108191.)

typing¶

• PEP 705: AddReadOnly, a special typing constructto mark aTypedDict item as read-only for type checkers.

• PEP 742: AddTypeIs, a typing constructthat can be used to instruct a type checker how to narrow a type.

• AddNoDefault, a sentinel object used to representthe defaults of some parameters in thetyping module.(Contributed by Jelle Zijlstra ingh-116126.)

• Addget_protocol_members() to return the set of membersdefining atyping.Protocol.(Contributed by Jelle Zijlstra ingh-104873.)

• Addis_protocol() to check whether a classis aProtocol.(Contributed by Jelle Zijlstra ingh-104873.)

• ClassVar can now be nested inFinal,and vice versa.(Contributed by Mehdi Drissi ingh-89547.)

unicodedata¶

• Update the Unicode database toversion 15.1.0.(Contributed by James Gerity ingh-109559.)

venv¶

• Add support for creating source control management (SCM) ignore filesin 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 ingh-108125.)

warnings¶

• PEP 702: The newwarnings.deprecated() decorator provides a way tocommunicate deprecations to astatic type checkerand to warn on usage of deprecated classes and functions.ADeprecationWarning may also be emitted whena decorated function or class is used at runtime.(Contributed by Jelle Zijlstra ingh-104003.)

xml¶

• Allow controlling Expat >=2.6.0 reparse deferral (CVE 2023-52425)by adding five new methods:

  • xml.etree.ElementTree.XMLParser.flush()

  • xml.etree.ElementTree.XMLPullParser.flush()

  • xml.parsers.expat.xmlparser.GetReparseDeferralEnabled()

  • xml.parsers.expat.xmlparser.SetReparseDeferralEnabled()

  • xml.sax.expatreader.ExpatParser.flush()

  (Contributed by Sebastian Pipping ingh-115623.)

• Add theclose() method for the iterator returned byiterparse() for explicit cleanup.(Contributed by Serhiy Storchaka ingh-69893.)

zipimport¶

• Add support forZIP64 format files.Everybody loves huge data, right?(Contributed by Tim Hatch ingh-94146.)

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 theirhistoric, 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 ofaifc library from PyPI.

• audioop

  • audioop-lts:Useaudioop-lts library from PyPI.

• chunk

  • standard-chunk:Use the redistribution ofchunk library from PyPI.

• cgi andcgitb

  • cgi.FieldStorage can typically be replaced withurllib.parse.parse_qsl() forGET andHEAD requests,and theemail.message module or themultipart libraryforPOST 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 functionalityin theemail package, which implements the same MIME RFCs.For example, withemail.message.EmailMessage:

    fromemail.messageimportEmailMessagemsg=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 functionalityin theemail package, which implements the same MIME RFCs,or with themultipart library.For example, theemail.message.EmailMessageandemail.message.Message classes.

  • standard-cgi: andstandard-cgitb:Use the redistribution ofcgi andcgitb library from PyPI.

• crypt and the private_crypt extension.Thehashlib module may be an appropriate replacementwhen 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 calland associated functionality.

  • crypt_r:Fork of thecrypt module,wrapper to thecrypt_r(3) library calland associated functionality.

  • standard-crypt anddeprecated-crypt-alternative:Use the redistribution ofcrypt and reimplementation of_crypt libraries from PyPI.

• imghdr:Thefiletype,puremagic, orpython-magic librariesshould be used as replacements.For example, thepuremagic.what() function can be usedto replace theimghdr.what() function for all file formatsthat were supported byimghdr.

  • standard-imghdr:Use the redistribution ofimghdr library from PyPI.

• mailcap:Use themimetypes module instead.

  • standard-mailcap:Use the redistribution ofmailcap library from PyPI.

• msilib

• nis

• nntplib:Use thepynntp library from PyPI instead.

  • standard-nntplib:Use the redistribution ofnntplib library from PyPI.

• ossaudiodev:For audio playback, use thepygame library from PyPI instead.

• pipes:Use thesubprocess module instead.Useshlex.quote() to replace the undocumentedpipes.quotefunction.

  • standard-pipes:Use the redistribution ofpipes library from PyPI.

• sndhdr:Thefiletype,puremagic, orpython-magic librariesshould be used as replacements.

  • standard-sndhdr:Use the redistribution ofsndhdr library from PyPI.

• spwd:Use thepython-pam library from PyPI instead.

• sunau

  • standard-sunau:Use the redistribution ofsunau library from PyPI.

• telnetlib,Use thetelnetlib3 orExscript libraries from PyPI instead.

  • standard-telnetlib:Use the redistribution oftelnetlib library from PyPI.

• uu:Use thebase64 module instead, as a modern alternative.

  • standard-uu:Use the redistribution ofuu library from PyPI.

• xdrlib

  • standard-xdrlib:Use the redistribution ofxdrlib library from PyPI.

(Contributed by Victor Stinner and Zachary Ware ingh-104773 andgh-104780.)

2to3¶

• Remove the2to3 program and thelib2to3 module,previously deprecated in Python 3.11.(Contributed by Victor Stinner ingh-104780.)

builtins¶

• Remove support for chainedclassmethod descriptors(introduced ingh-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 usingthe__wrapped__ attribute that was added in Python 3.10.(Contributed by Raymond Hettinger ingh-89519.)

• Raise aRuntimeError when callingframe.clear()on a suspended frame (as has always been the case for an executing frame).(Contributed by Irit Katriel ingh-79932.)

configparser¶

• Remove the undocumentedLegacyInterpolation class,deprecated in the docstring since Python 3.2,and at runtime since Python 3.11.(Contributed by Hugo van Kemenade ingh-104886.)

importlib.metadata¶

• Remove deprecated subscript (__getitem__()) access forEntryPoint objects.(Contributed by Jason R. Coombs ingh-113175.)

locale¶

• Remove thelocale.resetlocale() function, deprecated in Python 3.11.Uselocale.setlocale(locale.LC_ALL,"") instead.(Contributed by Victor Stinner ingh-104783.)

opcode¶

• Moveopcode.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 ingh-105481.)

• Removeopcode.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 ingh-105481.)

optparse¶

• This module is no longer consideredsoft deprecated.Whileargparse remains preferred for new projects thataren’t using a third party command line argument processinglibrary, there are aspects of the wayargparse works thatmean the lower leveloptparse module may provide a betterfoundation forwriting argument processing libraries, andfor implementing command line applications which adhere morestrictly thanargparse does to various Unix command lineprocessing conventions that originate in the behaviour of theCgetopt() function .(Contributed by Alyssa Coghlan and Serhiy Storchaka ingh-126180.)

pathlib¶

• Remove the ability to usePath objects as context managers.This functionality was deprecated and has had no effect since Python 3.9.(Contributed by Barney Gale ingh-83863.)

re¶

• Remove the undocumented, deprecated, and brokenre.template() function andre.TEMPLATE /re.T flag.(Contributed by Serhiy Storchaka and Nikita Sobolev ingh-105687.)

tkinter.tix¶

• Remove thetkinter.tix module, deprecated in Python 3.6.The third-party Tix library which the module wrapped is unmaintained.(Contributed by Zachary Ware ingh-75552.)

turtle¶

• Remove theRawTurtle.settiltangle() method,deprecated in the documentation since Python 3.1and at runtime since Python 3.11.(Contributed by Hugo van Kemenade ingh-104876.)

typing¶

• Remove thetyping.io andtyping.re namespaces,deprecated since Python 3.8.The items in those namespaces can be imported directlyfrom thetyping module.(Contributed by Sebastian Rittau ingh-92871.)

• Remove the keyword-argument method of creatingTypedDict types, deprecated in Python 3.11.(Contributed by Tomas Roun ingh-104786.)

unittest¶

• Remove the followingunittest functions, deprecated in Python 3.11:

  • unittest.findTestCases()

  • unittest.makeSuite()

  • unittest.getTestCaseNames()

  UseTestLoader methods instead:

  • loadTestsFromModule()

  • loadTestsFromTestCase()

  • getTestCaseNames()

  (Contributed by Hugo van Kemenade ingh-104835.)

• Remove the untested and undocumentedTestProgram.usageExit()method, deprecated in Python 3.11.(Contributed by Hugo van Kemenade ingh-104992.)

urllib¶

• Remove thecafile,capath, andcadefault parameters of theurllib.request.urlopen() function, deprecated in Python 3.6.Use thecontext parameter instead with anSSLContext instance.Thessl.SSLContext.load_cert_chain() functioncan be used to load specific certificates,or letssl.create_default_context() selectthe operating system’s trusted certificate authority (CA) certificates.(Contributed by Victor Stinner ingh-105382.)

webbrowser¶

• Remove the untested and undocumentedMacOSX class,deprecated in Python 3.11.Use theMacOSXOSAScript class (introduced in Python 3.2) instead.(Contributed by Hugo van Kemenade ingh-104804.)

• Remove the deprecatedMacOSXOSAScript._name attribute.Use theMacOSXOSAScript.nameattribute instead.(Contributed by Nikita Sobolev ingh-105546.)

Pending removal in Python 3.14¶

• argparse: Thetype,choices, andmetavar parametersofargparse.BooleanOptionalAction are deprecatedand will be removed in 3.14.(Contributed by Nikita Sobolev ingh-92248.)

• ast: The following features have been deprecated in documentationsince Python 3.8, now cause aDeprecationWarning to be emitted atruntime when they are accessed or used, and will be removed in Python 3.14:

  • ast.Num

  • ast.Str

  • ast.Bytes

  • ast.NameConstant

  • ast.Ellipsis

  Useast.Constant instead.(Contributed by Serhiy Storchaka ingh-90953.)

• asyncio:

  • The child watcher classesasyncio.MultiLoopChildWatcher,asyncio.FastChildWatcher,asyncio.AbstractChildWatcherandasyncio.SafeChildWatcher are deprecated andwill be removed in Python 3.14.(Contributed by Kumar Aditya ingh-94597.)

  • asyncio.set_child_watcher(),asyncio.get_child_watcher(),asyncio.AbstractEventLoopPolicy.set_child_watcher() andasyncio.AbstractEventLoopPolicy.get_child_watcher() are deprecatedand will be removed in Python 3.14.(Contributed by Kumar Aditya ingh-94597.)

  • Theget_event_loop() method of thedefault event loop policy now emits aDeprecationWarning if thereis no current event loop set and it decides to create one.(Contributed by Serhiy Storchaka and Guido van Rossum ingh-100160.)

• email: Deprecated theisdst parameter inemail.utils.localtime().(Contributed by Alan Williams ingh-72346.)

• importlib.abc deprecated classes:

  • importlib.abc.ResourceReader

  • importlib.abc.Traversable

  • importlib.abc.TraversableResources

  Useimportlib.resources.abc classes instead:

  • importlib.resources.abc.Traversable

  • importlib.resources.abc.TraversableResources

  (Contributed by Jason R. Coombs and Hugo van Kemenade ingh-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 codevolume and maintenance burden.(Contributed by Raymond Hettinger ingh-101588.)

• multiprocessing: The default start method will change to a safer one onLinux, BSDs, and other non-macOS POSIX platforms where'fork' is currentlythe default (gh-84559). Adding a runtime warning about this was deemed toodisruptive as the majority of code is not expected to care. Use theget_context() orset_start_method() APIs to explicitly specify whenyour coderequires'fork'. SeeContexts and start methods.

• pathlib:is_relative_to() andrelative_to(): passing additional arguments isdeprecated.

• pkgutil:pkgutil.find_loader() andpkgutil.get_loader()now raiseDeprecationWarning;useimportlib.util.find_spec() instead.(Contributed by Nikita Sobolev ingh-97850.)

• pty:

  • master_open(): usepty.openpty().

  • slave_open(): usepty.openpty().

• sqlite3:

  • version andversion_info.

  • execute() andexecutemany()ifnamed placeholders are used andparameters is a sequence instead of adict.

• urllib:urllib.parse.Quoter is deprecated: it was not intended to be apublic API.(Contributed by Gregory P. Smith ingh-88168.)

Pending removal in Python 3.15¶

• The import system:

  • Setting__cached__ on a module whilefailing to set__spec__.cachedis deprecated. In Python 3.15,__cached__ will cease to be set ortake into consideration by the import system or standard library. (gh-97879)

  • Setting__package__ on a module whilefailing to set__spec__.parentis deprecated. In Python 3.15,__package__ will cease to be set ortake into consideration by the import system or standard library. (gh-97879)

• ctypes:

  • The undocumentedctypes.SetPointerType() functionhas been deprecated since Python 3.13.

• http.server:

  • The obsolete and rarely usedCGIHTTPRequestHandlerhas been deprecated since Python 3.13.No direct replacement exists.Anything is better than CGI to interfacea web server with a request handler.

  • The--cgi flag to thepython -m http.servercommand-line interface has been deprecated since Python 3.13.

• importlib:

  • load_module() method: useexec_module() instead.

• locale:

  • Thegetdefaultlocale() functionhas 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 ingh-111187.)

• pathlib:

  • PurePath.is_reserved()has been deprecated since Python 3.13.Useos.path.isreserved() to detect reserved paths on Windows.

• platform:

  • java_ver() has been deprecated since Python 3.13.This function is only useful for Jython support, has a confusing API,and is largely untested.

• sysconfig:

  • Thecheck_home argument ofsysconfig.is_python_build() has beendeprecated since Python 3.12.

• threading:

  • RLock() will take no arguments in Python 3.15.Passing any arguments has been deprecated since Python 3.14,as the Python version does not permit any arguments,but the C version allows any number of positional or keyword arguments,ignoring every argument.

• types:

  • types.CodeType: Accessingco_lnotab wasdeprecated inPEP 626since 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 ingh-101866.)

• typing:

  • The undocumented keyword argument syntax for creatingNamedTuple 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 ofTypedDicts, failingto pass a value to thefields parameter (TD=TypedDict("TD")) orpassingNone (TD=TypedDict("TD",None)) has been deprecatedsince Python 3.13.UseclassTD(TypedDict):pass orTD=TypedDict("TD",{})to create a TypedDict with zero field.

  • Thetyping.no_type_check_decorator() decorator functionhas been deprecated since Python 3.13.After eight years in thetyping module,it has yet to be supported by any major type checker.

• wave:

  • Thegetmark(),setmark(),andgetmarkers() methods oftheWave_read andWave_write classeshave been deprecated since Python 3.13.

• zipimport:

  • load_module() has been deprecated sincePython 3.10. Useexec_module() instead.(Contributed by Jiahao Li ingh-125746.)

Pending removal in Python 3.16¶

• The import system:

  • Setting__loader__ on a module whilefailing to set__spec__.loaderis deprecated. In Python 3.16,__loader__ will cease to be set ortaken into consideration by the import system or the standard library.

• array:

  • The'u' format code (wchar_t)has been deprecated in documentation since Python 3.3and at runtime since Python 3.13.Use the'w' format code (Py_UCS4)for Unicode characters instead.

• asyncio:

  • asyncio.iscoroutinefunction() is deprecatedand will be removed in Python 3.16;useinspect.iscoroutinefunction() instead.(Contributed by Jiahao Li and Kumar Aditya ingh-122875.)

  • asyncio policy system is deprecated and will be removed in Python 3.16.In particular, the following classes and functions are deprecated:

    • asyncio.AbstractEventLoopPolicy

    • asyncio.DefaultEventLoopPolicy

    • asyncio.WindowsSelectorEventLoopPolicy

    • asyncio.WindowsProactorEventLoopPolicy

    • asyncio.get_event_loop_policy()

    • asyncio.set_event_loop_policy()

    Users should useasyncio.run() orasyncio.Runner withloop_factory to use the desired event loop implementation.

    For example, to useasyncio.SelectorEventLoop on Windows:

    importasyncioasyncdefmain():...asyncio.run(main(),loop_factory=asyncio.SelectorEventLoop)

    (Contributed by Kumar Aditya ingh-127949.)

• builtins:

  • Bitwise inversion on boolean types,~True or~Falsehas been deprecated since Python 3.12,as it produces surprising and unintuitive results (-2 and-1).Usenotx instead for the logical negation of a Boolean.In the rare case that you need the bitwise inversion ofthe underlying integer, convert toint explicitly (~int(x)).

• functools:

  • Calling the Python implementation offunctools.reduce() withfunctionorsequence as keyword arguments has been deprecated since Python 3.14.

• logging:

  Support for custom logging handlers with thestrm argument is deprecatedand scheduled for removal in Python 3.16. Define handlers with thestreamargument instead. (Contributed by Mariusz Felisiak ingh-115032.)

• mimetypes:

  • Valid extensions start with a ‘.’ or are empty formimetypes.MimeTypes.add_type().Undotted extensions are deprecated and willraise aValueError in Python 3.16.(Contributed by Hugo van Kemenade ingh-75223.)

• shutil:

  • TheExecError exceptionhas 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.

• symtable:

  • TheClass.get_methods methodhas been deprecated since Python 3.14.

• sys:

  • The_enablelegacywindowsfsencoding() functionhas been deprecated since Python 3.13.Use thePYTHONLEGACYWINDOWSFSENCODING environment variable instead.

• sysconfig:

  • Thesysconfig.expand_makefile_vars() functionhas been deprecated since Python 3.14.Use thevars argument ofsysconfig.get_paths() instead.

• tarfile:

  • The undocumented and unusedTarFile.tarfile attributehas been deprecated since Python 3.13.

Pending removal in Python 3.17¶

• collections.abc:

  • collections.abc.ByteString is scheduled for removal in Python 3.17.

    Useisinstance(obj,collections.abc.Buffer) to test ifobjimplements thebuffer protocol at runtime. For usein type annotations, either useBuffer or a unionthat explicitly specifies the types your code supports (e.g.,bytes|bytearray|memoryview).

    ByteString was originally intended to be an abstract class thatwould serve as a supertype of bothbytes andbytearray.However, since the ABC never had any methods, knowing that an object was aninstance ofByteString never actually told you anything usefulabout the object. Other common buffer types such asmemoryviewwere also never understood as subtypes ofByteString (either atruntime or by static type checkers).

    SeePEP 688 for more details.(Contributed by Shantanu Jain ingh-91896.)

• typing:

  • Before Python 3.14, old-style unions were implemented using the private classtyping._UnionGenericAlias. This class is no longer needed for the implementation,but it has been retained for backward compatibility, with removal scheduled for Python3.17. 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 inPython 3.17.

    Useisinstance(obj,collections.abc.Buffer) to test ifobjimplements thebuffer protocol at runtime. For usein type annotations, either useBuffer or a unionthat explicitly specifies the types your code supports (e.g.,bytes|bytearray|memoryview).

    ByteString was originally intended to be an abstract class thatwould serve as a supertype of bothbytes andbytearray.However, since the ABC never had any methods, knowing that an object was aninstance ofByteString never actually told you anything usefulabout the object. Other common buffer types such asmemoryviewwere also never understood as subtypes ofByteString (either atruntime or by static type checkers).

    SeePEP 688 for more details.(Contributed by Shantanu Jain ingh-91896.)

Pending removal in future versions¶

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

• argparse:

  • Nesting argument groups and nesting mutually exclusivegroups are deprecated.

  • Passing the undocumented keyword argumentprefix_chars toadd_argument_group() is nowdeprecated.

  • Theargparse.FileType type converter is deprecated.

• builtins:

  • 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 example0inx,1orx,0if1else2. It allows confusing andambiguous expressions like[0x1forxiny] (which can be interpreted as[0x1forxiny] or[0x1forxiny]). A syntax warning is raisedif the numeric literal is immediately followed by one of keywordsand,else,for,if,in,is andor. In a future release itwill 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.

  • Delegation ofint() to__trunc__() method.

  • Passing a complex number as thereal orimag argument in thecomplex() constructor is now deprecated; it should only be passedas a single positional argument.(Contributed by Serhiy Storchaka ingh-109218.)

• calendar:calendar.January andcalendar.February constants aredeprecated and replaced bycalendar.JANUARY andcalendar.FEBRUARY.(Contributed by Prince Roshan ingh-103636.)

• codecs: useopen() instead ofcodecs.open(). (gh-133038)

• codeobject.co_lnotab: use thecodeobject.co_lines() methodinstead.

• datetime:

  • utcnow():usedatetime.datetime.now(tz=datetime.UTC).

  • utcfromtimestamp():usedatetime.datetime.fromtimestamp(timestamp,tz=datetime.UTC).

• gettext: Plural value must be an integer.

• importlib:

  • cache_from_source()debug_override parameter isdeprecated: use theoptimization parameter instead.

• importlib.metadata:

  • EntryPoints tuple interface.

  • ImplicitNone on return values.

• logging: thewarn() method has been deprecatedsince Python 3.3, usewarning() instead.

• mailbox: Use of StringIO input and text mode is deprecated, useBytesIO and binary mode instead.

• os: Callingos.register_at_fork() in multi-threaded process.

• pydoc.ErrorDuringImport: A tuple value forexc_info parameter isdeprecated, use an exception instance.

• re: More strict rules are now applied for numerical group referencesand group names in regular expressions. Only sequence of ASCII digits is nowaccepted as a numerical reference. The group name in bytes patterns andreplacement strings can now only contain ASCII letters and digits andunderscore.(Contributed by Serhiy Storchaka ingh-91760.)

• sre_compile,sre_constants andsre_parse modules.

• shutil:rmtree()’sonerror parameter is deprecated inPython 3.12; use theonexc parameter instead.

• ssl options and protocols:

  • ssl.SSLContext without protocol argument is deprecated.

  • ssl.SSLContext:set_npn_protocols() andselected_npn_protocol() are deprecated: use ALPNinstead.

  • ssl.OP_NO_SSL* options

  • ssl.OP_NO_TLS* options

  • ssl.PROTOCOL_SSLv3

  • ssl.PROTOCOL_TLS

  • ssl.PROTOCOL_TLSv1

  • ssl.PROTOCOL_TLSv1_1

  • ssl.PROTOCOL_TLSv1_2

  • ssl.TLSVersion.SSLv3

  • ssl.TLSVersion.TLSv1

  • ssl.TLSVersion.TLSv1_1

• threading methods:

  • threading.Condition.notifyAll(): 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().

• typing.Text (gh-92332).

• The internal classtyping._UnionGenericAlias is no longer used to implementtyping.Union. To preserve compatibility with users using this privateclass, a compatibility shim will be provided until at least Python 3.17. (Contributed byJelle Zijlstra ingh-105499.)

• unittest.IsolatedAsyncioTestCase: it is deprecated to return a valuethat is notNone from a test case.

• urllib.parse deprecated functions:urlparse() instead

  • splitattr()

  • splithost()

  • splitnport()

  • splitpasswd()

  • splitport()

  • splitquery()

  • splittag()

  • splittype()

  • splituser()

  • splitvalue()

  • to_bytes()

• wsgiref:SimpleHandler.stdout.write() should not do partialwrites.

• xml.etree.ElementTree: Testing the truth value of anElement is deprecated. In a future release itwill always returnTrue. Prefer explicitlen(elem) orelemisnotNone tests instead.

• sys._clear_type_cache() is deprecated:usesys._clear_internal_caches() instead.

New Features¶

• Add thePyMonitoring C APIfor generatingPEP 669 monitoring events:

  • PyMonitoringState

  • PyMonitoring_FirePyStartEvent()

  • PyMonitoring_FirePyResumeEvent()

  • PyMonitoring_FirePyReturnEvent()

  • PyMonitoring_FirePyYieldEvent()

  • PyMonitoring_FireCallEvent()

  • PyMonitoring_FireLineEvent()

  • PyMonitoring_FireJumpEvent()

  • PyMonitoring_FireBranchEvent

  • PyMonitoring_FireCReturnEvent()

  • PyMonitoring_FirePyThrowEvent()

  • PyMonitoring_FireRaiseEvent()

  • PyMonitoring_FireCRaiseEvent()

  • PyMonitoring_FireReraiseEvent()

  • PyMonitoring_FireExceptionHandledEvent()

  • PyMonitoring_FirePyUnwindEvent()

  • PyMonitoring_FireStopIterationEvent()

  • PyMonitoring_EnterScope()

  • PyMonitoring_ExitScope()

  (Contributed by Irit Katriel ingh-111997).

• AddPyMutex, a lightweight mutex that occupies a single byte,and the newPyMutex_Lock() andPyMutex_Unlock() functions.PyMutex_Lock() will release theGIL (if currently held)if the operation needs to block.(Contributed by Sam Gross ingh-108724.)

• Add thePyTime C API to provide access to system clocks:

  • PyTime_t.

  • PyTime_MIN andPyTime_MAX.

  • PyTime_AsSecondsDouble().

  • PyTime_Monotonic().

  • PyTime_MonotonicRaw().

  • PyTime_PerfCounter().

  • PyTime_PerfCounterRaw().

  • PyTime_Time().

  • PyTime_TimeRaw().

  (Contributed by Victor Stinner and Petr Viktorin ingh-110850.)

• Add thePyDict_ContainsString() functionwith the same behavior asPyDict_Contains(),butkey is specified as aconstchar* UTF-8 encoded bytes string,rather than aPyObject*.(Contributed by Victor Stinner ingh-108314.)

• Add thePyDict_GetItemRef() andPyDict_GetItemStringRef()functions,which behave similarly toPyDict_GetItemWithError(),but return astrong reference instead of aborrowed reference.Moreover, these functions return-1 on error,removing the need to checkPyErr_Occurred().(Contributed by Victor Stinner ingh-106004.)

• Add thePyDict_SetDefaultRef() function,which behaves similarly toPyDict_SetDefault(),but returns astrong reference instead of aborrowed reference.This function returns-1 on error,0 on insertion,and1 if the key was already present in the dictionary.(Contributed by Sam Gross ingh-112066.)

• Add thePyDict_Pop() andPyDict_PopString() functionsto 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 ingh-111262.)

• Add thePyMapping_GetOptionalItem()andPyMapping_GetOptionalItemString() functionsas alternatives toPyObject_GetItem()andPyMapping_GetItemString() respectively.The new functions do not raiseKeyErrorif the requested key is missing from the mapping.These variants are more convenient and fasterif a missing key should not be treated as a failure.(Contributed by Serhiy Storchaka ingh-106307.)

• Add thePyObject_GetOptionalAttr()andPyObject_GetOptionalAttrString() functionsas alternatives toPyObject_GetAttr()andPyObject_GetAttrString() respectively.The new functions do not raiseAttributeErrorif the requested attribute is not found on the object.These variants are more convenient and fasterif the missing attribute should not be treated as a failure.(Contributed by Serhiy Storchaka ingh-106521.)

• Add thePyErr_FormatUnraisable() functionas an extension toPyErr_WriteUnraisable()that allows customizing the warning message.(Contributed by Serhiy Storchaka ingh-108082.)

• Add new functions that return astrong reference instead ofaborrowed reference for frame locals, globals, and builtins,as part ofPEP 667:

  • PyEval_GetFrameBuiltins() replacesPyEval_GetBuiltins()

  • PyEval_GetFrameGlobals() replacesPyEval_GetGlobals()

  • PyEval_GetFrameLocals() replacesPyEval_GetLocals()

  (Contributed by Mark Shannon and Tian Gao ingh-74929.)

• Add thePy_GetConstant() andPy_GetConstantBorrowed()functions to getstrongorborrowed references to constants.For example,Py_GetConstant(Py_CONSTANT_ZERO) returns a strong referenceto the constant zero.(Contributed by Victor Stinner ingh-115754.)

• Add thePyImport_AddModuleRef() functionas a replacement forPyImport_AddModule()that returns astrong reference instead of aborrowed reference.(Contributed by Victor Stinner ingh-105922.)

• Add thePy_IsFinalizing() function to checkwhether the main Python interpreter isshutting down.(Contributed by Victor Stinner ingh-108014.)

• Add thePyList_GetItemRef() functionas a replacement forPyList_GetItem()that returns astrong reference instead of aborrowed reference.(Contributed by Sam Gross ingh-114329.)

• Add thePyList_Extend() andPyList_Clear() functions,mirroring the Pythonlist.extend() andlist.clear() methods.(Contributed by Victor Stinner ingh-111138.)

• Add thePyLong_AsInt() function.It behaves similarly toPyLong_AsLong(),but stores the result in a Cint instead of a Clong.(Contributed by Victor Stinner ingh-108014.)

• Add thePyLong_AsNativeBytes(),PyLong_FromNativeBytes(),andPyLong_FromUnsignedNativeBytes() functionsto simplify converting between native integer typesand Pythonint objects.(Contributed by Steve Dower ingh-111140.)

• AddPyModule_Add() function, which is similar toPyModule_AddObjectRef() andPyModule_AddObject(),but always steals a reference to the value.(Contributed by Serhiy Storchaka ingh-86493.)

• Add thePyObject_GenericHash() functionthat implements the default hashing function of a Python object.(Contributed by Serhiy Storchaka ingh-113024.)

• Add thePy_HashPointer() function to hash a raw pointer.(Contributed by Victor Stinner ingh-111545.)

• Add thePyObject_VisitManagedDict() andPyObject_ClearManagedDict() functions.which must be called by the traverse and clear functions of a type usingthePy_TPFLAGS_MANAGED_DICT flag.Thepythoncapi-compat project can be used touse these functions with Python 3.11 and 3.12.(Contributed by Victor Stinner ingh-107073.)

• Add thePyRefTracer_SetTracer()andPyRefTracer_GetTracer() functions,which enable tracking object creation and destructionin the same way that thetracemalloc module does.(Contributed by Pablo Galindo ingh-93502.)

• Add thePySys_AuditTuple() functionas an alternative toPySys_Audit()that takes event arguments as a Pythontuple object.(Contributed by Victor Stinner ingh-85283.)

• Add thePyThreadState_GetUnchecked() functionas 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 ingh-108867.)

• Add thePyType_GetFullyQualifiedName() functionto get the type’s fully qualified name.The module name is prepended iftype.__module__ isa string and is not equal to either'builtins' or'__main__'.(Contributed by Victor Stinner ingh-111696.)

• Add thePyType_GetModuleName() functionto get the type’s module name. This is equivalent to getting thetype.__module__ attribute.(Contributed by Eric Snow and Victor Stinner ingh-111696.)

• Add thePyUnicode_EqualToUTF8AndSize()andPyUnicode_EqualToUTF8() functionsto compare a Unicode object with aconstchar* UTF-8 encoded stringand1 if they are equal or0 otherwise.These functions do not raise exceptions.(Contributed by Serhiy Storchaka ingh-110289.)

• Add thePyWeakref_GetRef() functionas an alternative toPyWeakref_GetObject()that returns astrong referenceorNULL if the referent is no longer live.(Contributed by Victor Stinner ingh-105927.)

• Add fixed variants of functions which silently ignore errors:

  • PyObject_HasAttrWithError() replacesPyObject_HasAttr().

  • PyObject_HasAttrStringWithError()replacesPyObject_HasAttrString().

  • PyMapping_HasKeyWithError() replacesPyMapping_HasKey().

  • PyMapping_HasKeyStringWithError()replacesPyMapping_HasKeyString().

  The new functions return-1 for errorsand the standard1 for true and0 for false.

  (Contributed by Serhiy Storchaka ingh-108511.)

Changed C APIs¶

• Thekeywords parameter ofPyArg_ParseTupleAndKeywords()andPyArg_VaParseTupleAndKeywords()now has typechar*const* in Candconstchar*const* in C++,instead ofchar**.In C++, this makes these functions compatible with argumentsof typeconstchar*const*,constchar**,orchar*const* without an explicit type cast.In C, the functions only support arguments of typechar*const*.This can be overridden with thePY_CXX_CONST macro.(Contributed by Serhiy Storchaka ingh-65210.)

• PyArg_ParseTupleAndKeywords() now supportsnon-ASCII keyword parameter names.(Contributed by Serhiy Storchaka ingh-110815.)

• ThePyCode_GetFirstFree() function is now unstable APIand is now namedPyUnstable_Code_GetFirstFree().(Contributed by Bogdan Romanyuk ingh-115781.)

• ThePyDict_GetItem(),PyDict_GetItemString(),PyMapping_HasKey(),PyMapping_HasKeyString(),PyObject_HasAttr(),PyObject_HasAttrString(),andPySys_GetObject() functions,each of which clears all errors which occurred when calling themnow reports these errors usingsys.unraisablehook().You may replace them with other functions as recommended in the documentation.(Contributed by Serhiy Storchaka ingh-106672.)

• Add support for the%T,%#T,%N and%#N formatstoPyUnicode_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

  SeePEP 737 for more information.(Contributed by Victor Stinner ingh-111696.)

• You no longer have to define thePY_SSIZE_T_CLEAN macro beforeincludingPython.h when using# formats informat codes.APIs accepting the format codes always usePy_ssize_t for# formats.(Contributed by Inada Naoki ingh-104922.)

• If Python is built indebug modeorwithassertions,PyTuple_SET_ITEM() andPyList_SET_ITEM()now check the index argument with an assertion.(Contributed by Victor Stinner ingh-106168.)

Limited C API Changes¶

• The following functions are now included in the Limited C API:

  • PyMem_RawMalloc()

  • PyMem_RawCalloc()

  • PyMem_RawRealloc()

  • PyMem_RawFree()

  • PySys_Audit()

  • PySys_AuditTuple()

  • PyType_GetModuleByDef()

  (Contributed by Victor Stinner ingh-85283,gh-85283, andgh-116936.)

• Python built with--with-trace-refs (tracing references)now supports theLimited API.(Contributed by Victor Stinner ingh-108634.)

Removed C APIs¶

• Remove several functions, macros, variables, etcwith names prefixed by_Py or_PY (which are considered private).If your project is affected by one of these removalsand you believe that the removed API should remain available,pleaseopen a new issue to request a public C APIand addcc:@vstinner to the issue to notify Victor Stinner.(Contributed by Victor Stinner ingh-106320.)

• Remove old buffer protocols deprecated in Python 3.0.UseBuffer Protocol instead.

  • PyObject_CheckReadBuffer():UsePyObject_CheckBuffer() to testwhether the object supports the buffer protocol.Note thatPyObject_CheckBuffer() doesn’t guaranteethatPyObject_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_bufferview;if(PyObject_GetBuffer(obj,&view,PyBUF_SIMPLE)<0){returnNULL;}// 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_bufferview;if(PyObject_GetBuffer(obj,&view,PyBUF_WRITABLE)<0){returnNULL;}// Use `view.buf` and `view.len` to write to the buffer.PyBuffer_Release(&view);

  (Contributed by Inada Naoki ingh-85275.)

• Remove various functions deprecated in Python 3.9:

  • PyEval_CallObject(),PyEval_CallObjectWithKeywords():UsePyObject_CallNoArgs() orPyObject_Call() instead.

    Warning

    InPyObject_Call(), positional arguments must be atupleand must not beNULL,and keyword arguments must be adict orNULL,whereas the removed functions checked argument typesand 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 ingh-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 newPyConfig API of thePython InitializationConfiguration instead (PEP 587), added to Python 3.8.(Contributed by Victor Stinner ingh-105145.)

• RemovePyEval_AcquireLock() andPyEval_ReleaseLock() functions,deprecated in Python 3.2.They didn’t update the current thread state.They can be replaced with:

  • PyEval_SaveThread() andPyEval_RestoreThread();

  • low-levelPyEval_AcquireThread() andPyEval_RestoreThread();

  • orPyGILState_Ensure() andPyGILState_Release().

  (Contributed by Victor Stinner ingh-105182.)

• Remove thePyEval_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 ingh-105182.)

• Remove the_PyInterpreterState_Get() alias toPyInterpreterState_Get()which was kept for backward compatibility with Python 3.8.Thepythoncapi-compat project can be used to getPyInterpreterState_Get() on Python 3.8 and older.(Contributed by Victor Stinner ingh-106320.)

• Remove the private_PyObject_FastCall() function:usePyObject_Vectorcall() which is available since Python 3.8(PEP 590).(Contributed by Victor Stinner ingh-106023.)

• Remove thecpython/pytime.h header file,which only contained private functions.(Contributed by Victor Stinner ingh-106316.)

• Remove the undocumentedPY_TIMEOUT_MAX constant from the limited C API.(Contributed by Victor Stinner ingh-110014.)

• Remove the old trashcan macrosPy_TRASHCAN_SAFE_BEGINandPy_TRASHCAN_SAFE_END.Replace both with the new macrosPy_TRASHCAN_BEGINandPy_TRASHCAN_END.(Contributed by Irit Katriel ingh-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.homeor thePYTHONHOME environment variable instead.

  (Contributed by Victor Stinner ingh-105145.)

• Soft deprecate thePyEval_GetBuiltins(),PyEval_GetGlobals(),andPyEval_GetLocals() functions,which return aborrowed reference.(Soft deprecated as part ofPEP 667.)

• Deprecate thePyImport_ImportModuleNoBlock() function,which is just an alias toPyImport_ImportModule() since Python 3.3.(Contributed by Victor Stinner ingh-105396.)

• Soft deprecate thePyModule_AddObject() function.It should be replaced withPyModule_Add()orPyModule_AddObjectRef().(Contributed by Serhiy Storchaka ingh-86493.)

• Deprecate the oldPy_UNICODE andPY_UNICODE_TYPE typesand thePy_UNICODE_WIDE define.Use thewchar_t type directly instead.Since Python 3.3,Py_UNICODE andPY_UNICODE_TYPEare just aliases towchar_t.(Contributed by Victor Stinner ingh-105156.)

• Deprecate thePyWeakref_GetObject() andPyWeakref_GET_OBJECT() functions,which return aborrowed reference.Replace them with the newPyWeakref_GetRef() function,which returns astrong reference.Thepythoncapi-compat project can be used to getPyWeakref_GetRef() on Python 3.12 and older.(Contributed by Victor Stinner ingh-105927.)

Changes in the Python API¶

• PEP 667 introduces several changesto the semantics oflocals() andf_locals:

  • Callinglocals() in anoptimized scope now produces anindependent snapshot on each call, and hence no longer implicitly updatespreviously returned references. Obtaining the legacy CPython behavior nowrequires explicit calls to update the initially returned dictionary with theresults of subsequent calls tolocals(). Code execution functions thatimplicitly targetlocals() (such asexec andeval) must bepassed an explicit namespace to access their results in an optimized scope.(Changed as part ofPEP 667.)

  • Callinglocals() from a comprehension at module or class scope(including viaexec oreval) once more behaves as if the comprehensionwere running as an independent nested function (i.e. the local variables fromthe containing scope are not included). In Python 3.12, this had changedto include the local variables from the containing scope when implementingPEP 709. (Changed as part ofPEP 667.)

  • AccessingFrameType.f_locals in anoptimized scope now returns a write-through proxy rather than asnapshot 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 ofPEP 667.)

• functools.partial now emits aFutureWarningwhen 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 ingh-121027.)

• AnOSError is now raised bygetpass.getuser()for any failure to retrieve a username,instead ofImportError on non-Unix platformsorKeyError on Unix platforms where the password database is empty.

• The value of themode attribute ofgzip.GzipFileis now a string ('rb' or'wb') instead of an integer (1 or2).The value of themode attribute of the readable file-like objectreturned byzipfile.ZipFile.open() is now'rb' instead of'r'.(Contributed by Serhiy Storchaka ingh-115961.)

• mailbox.Maildir now ignores files with a leading dot (.).(Contributed by Zackery Spytz ingh-65559.)

• pathlib.Path.glob() andrglob() now return bothfiles 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.

• Thethreading module now expects the_thread moduleto have an_is_main_interpreter() function.This function takes no arguments and returnsTrueif the current interpreter is the main interpreter.

  Any library or application that provides a custom_thread modulemust 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 wasincluded for thefinite() function which is now provided by the<math.h> header. It should now be included explicitly if needed. Removealso theHAVE_IEEEFP_H macro.(Contributed by Victor Stinner ingh-108765.)

• Python.h no longer includes these standard header files:<time.h>,<sys/select.h> and<sys/time.h>. If needed, they should now beincluded 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 ingh-108765.)

• On Windows,Python.h no longer includes the<stddef.h> standardheader file. If needed, it should now be included explicitly. For example, itprovidesoffsetof() function, andsize_t andptrdiff_t types.Including<stddef.h> explicitly was already needed by all otherplatforms, theHAVE_STDDEF_H macro is only defined on Windows.(Contributed by Victor Stinner ingh-108765.)

• If thePy_LIMITED_API macro is defined,Py_BUILD_CORE,Py_BUILD_CORE_BUILTIN andPy_BUILD_CORE_MODULE macrosare now undefined by<Python.h>.(Contributed by Victor Stinner ingh-85283.)

• The old trashcan macrosPy_TRASHCAN_SAFE_BEGIN andPy_TRASHCAN_SAFE_ENDwere removed. They should be replaced by the new macrosPy_TRASHCAN_BEGINandPy_TRASHCAN_END.

  Atp_dealloc function that has the old macros, such as:

  staticvoidmytype_dealloc(mytype*p){PyObject_GC_UnTrack(p);Py_TRASHCAN_SAFE_BEGIN(p);...Py_TRASHCAN_SAFE_END}

  should migrate to the new macros as follows:

  staticvoidmytype_dealloc(mytype*p){PyObject_GC_UnTrack(p);Py_TRASHCAN_BEGIN(p,mytype_dealloc)...Py_TRASHCAN_END}

  Note thatPy_TRASHCAN_BEGIN has a second argument whichshould be the deallocation function it is in. The new macros wereadded in Python 3.8 and the old macros were deprecated in Python 3.11.(Contributed by Irit Katriel ingh-105111.)

• PEP 667 introduces several changesto frame-related functions:

  • The effects of mutating the dictionary returned fromPyEval_GetLocals() in anoptimized scope have changed.New dict entries added this way will nowonly be visible tosubsequentPyEval_GetLocals() calls in that frame,asPyFrame_GetLocals(),locals(),andFrameType.f_locals no longer accessthe same underlying cached dictionary.Changes made to entries for actual variable names and names added viathe write-through proxy interfaces will be overwritten on subsequent callstoPyEval_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.

  • CallingPyFrame_GetLocals() in anoptimized scopenow returns a write-through proxy rather than a snapshotthat 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 foroptimized scopes.

• Python 3.13 removed many private functions. Some of them can be replaced using thesealternatives:

  • _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().

  Thepythoncapi-compat project can be used to get most of these newfunctions on Python 3.12 and older.