# What\'s new in Python 3.14 Editors : Adam Turner and Hugo van Kemenade > \* Anyone can add text to this document. Do not spend very much time on the wording of your changes, because your text will probably get rewritten to some degree. > > \* The maintainer will go through Misc/NEWS periodically and add changes; it\'s therefore more important to add your changes to Misc/NEWS than to this file. > > \* This is not a complete list of every single change; completeness is the purpose of Misc/NEWS. Some changes I consider too small or esoteric to include. If such a change is added to the text, I\'ll just remove it. (This is another reason you shouldn\'t spend too much time on writing your addition.) > > \* If you want to draw your new text to the attention of the maintainer, add \'XXX\' to the beginning of the paragraph or section. > > \* It\'s OK to just add a fragmentary note about a change. For example: \"XXX Describe the transmogrify() function added to the socket module.\" The maintainer will research the change and write the necessary text. > > \* You can comment out your additions if you like, but it\'s not necessary (especially when a final release is some months away). > > \* Credit the author of a patch or bugfix. Just the name is sufficient; the e-mail address isn\'t necessary. > > - It\'s helpful to add the issue number as a comment: > > XXX Describe the transmogrify() function added to the socket module. (Contributed by P.Y. Developer in `12345`{.interpreted-text role="gh"}.) > > This saves the maintainer the effort of going through the VCS log when researching a change. This article explains the new features in Python 3.14, compared to 3.13. Python 3.14 was released on 7 October 2025. For full details, see the `changelog `{.interpreted-text role="ref"}. ::: seealso `745`{.interpreted-text role="pep"} \-- Python 3.14 release schedule ::: ## Summary \-- Release highlights Python 3.14 is the latest 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 `template string literals `{.interpreted-text role="ref"}, `deferred evaluation of annotations `{.interpreted-text role="ref"}, and support for `subinterpreters `{.interpreted-text role="ref"} in the standard library. The library changes include significantly improved capabilities for `introspection in asyncio `{.interpreted-text role="ref"}, `support for Zstandard `{.interpreted-text role="ref"} via a new `compression.zstd`{.interpreted-text role="mod"} module, syntax highlighting in the REPL, as well as the usual deprecations and removals, and improvements in user-friendliness and correctness. 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 `{.interpreted-text role="ref"} and `Language Reference `{.interpreted-text role="ref"}. 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 3.14](#porting-to-python-3.14) for guidance on upgrading from earlier versions of Python. ------------------------------------------------------------------------ Interpreter improvements: - `649`{.interpreted-text role="pep"} and `749`{.interpreted-text role="pep"}: `Deferred evaluation of annotations `{.interpreted-text role="ref"} - `734`{.interpreted-text role="pep"}: `Multiple interpreters in the standard library `{.interpreted-text role="ref"} - `750`{.interpreted-text role="pep"}: `Template strings `{.interpreted-text role="ref"} - `758`{.interpreted-text role="pep"}: `Allow except and except* expressions without brackets `{.interpreted-text role="ref"} - `765`{.interpreted-text role="pep"}: `Control flow in finally blocks `{.interpreted-text role="ref"} - `768`{.interpreted-text role="pep"}: `Safe external debugger interface for CPython `{.interpreted-text role="ref"} - `A new type of interpreter `{.interpreted-text role="ref"} - `Free-threaded mode improvements `{.interpreted-text role="ref"} - `Improved error messages `{.interpreted-text role="ref"} - `Incremental garbage collection `{.interpreted-text role="ref"} Significant improvements in the standard library: - `784`{.interpreted-text role="pep"}: `Zstandard support in the standard library `{.interpreted-text role="ref"} - `whatsnew314-asyncio-introspection`{.interpreted-text role="ref"} - `whatsnew314-concurrent-warnings-control`{.interpreted-text role="ref"} - `Syntax highlighting in the default interactive shell `{.interpreted-text role="ref"}, and color output in several standard library CLIs C API improvements: - `741`{.interpreted-text role="pep"}: `Python configuration C API `{.interpreted-text role="ref"} Platform support: - `776`{.interpreted-text role="pep"}: Emscripten is now an `officially supported platform `{.interpreted-text role="ref"}, at `tier 3 <11#tier-3>`{.interpreted-text role="pep"}. Release changes: - `779`{.interpreted-text role="pep"}: `Free-threaded Python is officially supported `{.interpreted-text role="ref"} - `761`{.interpreted-text role="pep"}: `PGP signatures have been discontinued for official releases `{.interpreted-text role="ref"} - `Windows and macOS binary releases now support the experimental just-in-time compiler `{.interpreted-text role="ref"} - `Binary releases for Android are now provided `{.interpreted-text role="ref"} ## New features ### `649`{.interpreted-text role="pep"} & `749`{.interpreted-text role="pep"}: Deferred evaluation of annotations {#whatsnew314-deferred-annotations} The `annotations `{.interpreted-text role="term"} on functions, classes, and modules are no longer evaluated eagerly. Instead, annotations are stored in special-purpose `annotate functions `{.interpreted-text role="term"} and evaluated only when necessary (except if `from __future__ import annotations` is used). This change is designed to improve performance and usability of annotations in Python in most circumstances. The runtime cost for defining annotations is minimized, but it remains possible to introspect annotations at runtime. It is no longer necessary to enclose annotations in strings if they contain forward references. The new `annotationlib`{.interpreted-text role="mod"} module provides tools for inspecting deferred annotations. Annotations may be evaluated in the `~annotationlib.Format.VALUE`{.interpreted-text role="attr"} format (which evaluates annotations to runtime values, similar to the behavior in earlier Python versions), the `~annotationlib.Format.FORWARDREF`{.interpreted-text role="attr"} format (which replaces undefined names with special markers), and the `~annotationlib.Format.STRING`{.interpreted-text role="attr"} format (which returns annotations as strings). This example shows how these formats behave: ::: doctest \>\>\> from annotationlib import get_annotations, Format \>\>\> def func(arg: Undefined): \... pass \>\>\> get_annotations(func, format=Format.VALUE) Traceback (most recent call last): \... NameError: name \'Undefined\' is not defined \>\>\> get_annotations(func, format=Format.FORWARDREF) {\'arg\': ForwardRef(\'Undefined\', owner=\)} \>\>\> get_annotations(func, format=Format.STRING) {\'arg\': \'Undefined\'} ::: The `porting `{.interpreted-text role="ref"} section contains guidance on changes that may be needed due to these changes, though in the majority of cases, code will continue working as-is. (Contributed by Jelle Zijlstra in `749`{.interpreted-text role="pep"} and `119180`{.interpreted-text role="gh"}; `649`{.interpreted-text role="pep"} was written by Larry Hastings.) ::: seealso `649`{.interpreted-text role="pep"} : Deferred Evaluation Of Annotations Using Descriptors `749`{.interpreted-text role="pep"} : Implementing PEP 649 ::: ### `734`{.interpreted-text role="pep"}: Multiple interpreters in the standard library {#whatsnew314-multiple-interpreters} The CPython runtime supports running multiple copies of Python in the same process simultaneously and has done so for over 20 years. Each of these separate copies is called an \'interpreter\'. However, the feature had been available only through the `C-API `{.interpreted-text role="ref"}. That limitation is removed in Python 3.14, with the new `concurrent.interpreters`{.interpreted-text role="mod"} module. There are at least two notable reasons why using multiple interpreters has significant benefits: - they support a new (to Python), human-friendly concurrency model - true multi-core parallelism For some use cases, concurrency in software improves efficiency and can simplify design, at a high level. At the same time, implementing and maintaining all but the simplest concurrency is often a struggle for the human brain. That especially applies to plain threads (for example, `threading`{.interpreted-text role="mod"}), where all memory is shared between all threads. With multiple isolated interpreters, you can take advantage of a class of concurrency models, like Communicating Sequential Processes (CSP) or the actor model, that have found success in other programming languages, like Smalltalk, Erlang, Haskell, and Go. Think of multiple interpreters as threads but with opt-in sharing. Regarding multi-core parallelism: as of Python 3.12, interpreters are now sufficiently isolated from one another to be used in parallel (see `684`{.interpreted-text role="pep"}). This unlocks a variety of CPU-intensive use cases for Python that were limited by the `GIL`{.interpreted-text role="term"}. Using multiple interpreters is similar in many ways to `multiprocessing`{.interpreted-text role="mod"}, in that they both provide isolated logical \"processes\" that can run in parallel, with no sharing by default. However, when using multiple interpreters, an application will use fewer system resources and will operate more efficiently (since it stays within the same process). Think of multiple interpreters as having the isolation of processes with the efficiency of threads. While the feature has been around for decades, multiple interpreters have not been used widely, due to low awareness and the lack of a standard library module. Consequently, they currently have several notable limitations, which are expected to improve significantly now that the feature is going mainstream. Current limitations: - starting each interpreter has not been optimized yet - each interpreter uses more memory than necessary (work continues on extensive internal sharing between interpreters) - there aren\'t many options *yet* for truly sharing objects or other data between interpreters (other than `memoryview`{.interpreted-text role="type"}) - many third-party extension modules on PyPI are not yet compatible with multiple interpreters (all standard library extension modules *are* compatible) - the approach to writing applications that use multiple isolated interpreters is mostly unfamiliar to Python users, for now The impact of these limitations will depend on future CPython improvements, how interpreters are used, and what the community solves through PyPI packages. Depending on the use case, the limitations may not have much impact, so try it out! Furthermore, future CPython releases will reduce or eliminate overhead and provide utilities that are less appropriate on PyPI. In the meantime, most of the limitations can also be addressed through extension modules, meaning PyPI packages can fill any gap for 3.14, and even back to 3.12 where interpreters were finally properly isolated and stopped sharing the `GIL`{.interpreted-text role="term"}. Likewise, libraries on PyPI are expected to emerge for high-level abstractions on top of interpreters. Regarding extension modules, work is in progress to update some PyPI projects, as well as tools like Cython, pybind11, nanobind, and PyO3. The steps for isolating an extension module are found at `isolating-extensions-howto`{.interpreted-text role="ref"}. Isolating a module has a lot of overlap with what is required to support `free-threading `{.interpreted-text role="ref"}, so the ongoing work in the community in that area will help accelerate support for multiple interpreters. Also added in 3.14: `concurrent.futures.InterpreterPoolExecutor `{.interpreted-text role="ref"}. (Contributed by Eric Snow in `134939`{.interpreted-text role="gh"}.) ::: seealso `734`{.interpreted-text role="pep"} ::: ### `750`{.interpreted-text role="pep"}: Template string literals {#whatsnew314-template-string-literals} Template strings are a new mechanism for custom string processing. They share the familiar syntax of f-strings but, unlike f-strings, return an object representing the static and interpolated parts of the string, instead of a simple `str`{.interpreted-text role="class"}. To write a t-string, use a `'t'` prefix instead of an `'f'`: ::: doctest \>\>\> variety = \'Stilton\' \>\>\> template = t\'Try some {variety} cheese!\' \>\>\> type(template) \ ::: `~string.templatelib.Template`{.interpreted-text role="class"} objects provide access to the static and interpolated (in curly braces) parts of a string *before* they are combined. Iterate over `!Template`{.interpreted-text role="class"} instances to access their parts in order: ::: testsetup variety = \'Stilton\' template = t\'Try some {variety} cheese!\' ::: ::: doctest \>\>\> list(template) \[\'Try some \', Interpolation(\'Stilton\', \'variety\', None, \'\'), \' cheese!\'\] ::: It\'s easy to write (or call) code to process `!Template`{.interpreted-text role="class"} instances. For example, here\'s a function that renders static parts lowercase and `~string.templatelib.Interpolation`{.interpreted-text role="class"} instances uppercase: ``` python from string.templatelib import Interpolation def lower_upper(template): """Render static parts lowercase and interpolations uppercase.""" parts = [] for part in template: if isinstance(part, Interpolation): parts.append(str(part.value).upper()) else: parts.append(part.lower()) return ''.join(parts) name = 'Wenslydale' template = t'Mister {name}' assert lower_upper(template) == 'mister WENSLYDALE' ``` Because `!Template`{.interpreted-text role="class"} instances distinguish between static strings and interpolations at runtime, they can be useful for sanitising user input. Writing a `!html`{.interpreted-text role="func"} function that escapes user input in HTML is an exercise left to the reader! Template processing code can provide improved flexibility. For instance, a more advanced `!html`{.interpreted-text role="func"} function could accept a `!dict`{.interpreted-text role="class"} of HTML attributes directly in the template: ``` python attributes = {'src': 'limburger.jpg', 'alt': 'lovely cheese'} template = t'' assert html(template) == 'lovely cheese' ``` Of course, template processing code does not need to return a string-like result. An even *more* advanced `!html`{.interpreted-text role="func"} could return a custom type representing a DOM-like structure. With t-strings in place, developers can write systems that sanitise SQL, make safe shell operations, improve logging, tackle modern ideas in web development (HTML, CSS, and so on), and implement lightweight custom business DSLs. (Contributed by Jim Baker, Guido van Rossum, Paul Everitt, Koudai Aono, Lysandros Nikolaou, Dave Peck, Adam Turner, Jelle Zijlstra, Bénédikt Tran, and Pablo Galindo Salgado in `132661`{.interpreted-text role="gh"}.) ::: seealso `750`{.interpreted-text role="pep"}. ::: ### `768`{.interpreted-text role="pep"}: Safe external debugger interface {#whatsnew314-remote-debugging} Python 3.14 introduces a zero-overhead debugging interface that allows debuggers and profilers to safely attach to running Python processes without stopping or restarting them. This is a significant enhancement to Python\'s debugging capabilities, meaning that unsafe alternatives are no longer required. The new interface provides safe execution points for attaching debugger code without modifying the interpreter\'s normal execution path or adding any overhead at runtime. Due to this, tools can now inspect and interact with Python applications in real-time, which is a crucial capability for high-availability systems and production environments. For convenience, this interface is implemented in the `sys.remote_exec`{.interpreted-text role="func"} function. For example: ``` python import sys from tempfile import NamedTemporaryFile with NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f: script_path = f.name f.write(f'import my_debugger; my_debugger.connect({os.getpid()})') # Execute in process with PID 1234 print('Behold! An offering:') sys.remote_exec(1234, script_path) ``` This function allows sending Python code to be executed in a target process at the next safe execution point. However, tool authors can also implement the protocol directly as described in the PEP, which details the underlying mechanisms used to safely attach to running processes. The debugging interface has been carefully designed with security in mind and includes several mechanisms to control access: - A `PYTHON_DISABLE_REMOTE_DEBUG`{.interpreted-text role="envvar"} environment variable. - A `-X disable-remote-debug`{.interpreted-text role="option"} command-line option. - A `--without-remote-debug`{.interpreted-text role="option"} configure flag to completely disable the feature at build time. (Contributed by Pablo Galindo Salgado, Matt Wozniski, and Ivona Stojanovic in `131591`{.interpreted-text role="gh"}.) ::: seealso `768`{.interpreted-text role="pep"}. ::: ### A new type of interpreter {#whatsnew314-tail-call-interpreter} A new type of interpreter has been added to CPython. It uses tail calls between small C functions that implement individual Python opcodes, rather than one large C `case` statement. For certain newer compilers, this interpreter provides significantly better performance. Preliminary benchmarks suggest a geometric mean of 3-5% faster on the standard `pyperformance` benchmark suite, depending on platform and architecture. The baseline is Python 3.14 built with Clang 19, without this new interpreter. This interpreter currently only works with Clang 19 and newer on x86-64 and AArch64 architectures. However, a future release of GCC is expected to support this as well. This feature is opt-in for now. Enabling profile-guided optimization is highly recommendeded when using the new interpreter as it is the only configuration that has been tested and validated for improved performance. For further information, see `--with-tail-call-interp`{.interpreted-text role="option"}. :::: note ::: title Note ::: This is not to be confused with [tail call optimization](https://en.wikipedia.org/wiki/Tail_call) of Python functions, which is currently not implemented in CPython. This new interpreter type is an internal implementation detail of the CPython interpreter. It doesn\'t change the visible behavior of Python programs at all. It can improve their performance, but doesn\'t change anything else. :::: (Contributed by Ken Jin in `128563`{.interpreted-text role="gh"}, with ideas on how to implement this in CPython by Mark Shannon, Garrett Gu, Haoran Xu, and Josh Haberman.) ### Free-threaded mode improvements {#whatsnew314-free-threaded-cpython} CPython\'s free-threaded mode (`703`{.interpreted-text role="pep"}), initially added in 3.13, has been significantly improved in Python 3.14. The implementation described in PEP 703 has been finished, including C API changes, and temporary workarounds in the interpreter were replaced with more permanent solutions. The specializing adaptive interpreter (`659`{.interpreted-text role="pep"}) is now enabled in free-threaded mode, which along with many other optimizations greatly improves its performance. The performance penalty on single-threaded code in free-threaded mode is now roughly 5-10%, depending on the platform and C compiler used. From Python 3.14, when compiling extension modules for the free-threaded build of CPython on Windows, the preprocessor variable `Py_GIL_DISABLED` now needs to be specified by the build backend, as it will no longer be determined automatically by the C compiler. For a running interpreter, the setting that was used at compile time can be found using `sysconfig.get_config_var`{.interpreted-text role="func"}. The new `-X context_aware_warnings <-X>`{.interpreted-text role="option"} flag controls if `concurrent safe warnings control `{.interpreted-text role="ref"} is enabled. The flag defaults to true for the free-threaded build and false for the GIL-enabled build. A new `~sys.flags.thread_inherit_context`{.interpreted-text role="data"} flag has been added, which if enabled means that threads created with `threading.Thread`{.interpreted-text role="class"} start with a copy of the `~contextvars.Context()`{.interpreted-text role="class"} of the caller of `~threading.Thread.start`{.interpreted-text role="meth"}. Most significantly, this makes the warning filtering context established by `~warnings.catch_warnings`{.interpreted-text role="class"} be \"inherited\" by threads (or asyncio tasks) started within that context. It also affects other modules that use context variables, such as the `decimal`{.interpreted-text role="mod"} context manager. This flag defaults to true for the free-threaded build and false for the GIL-enabled build. (Contributed by Sam Gross, Matt Page, Neil Schemenauer, Thomas Wouters, Donghee Na, Kirill Podoprigora, Ken Jin, Itamar Oren, Brett Simmers, Dino Viehland, Nathan Goldbaum, Ralf Gommers, Lysandros Nikolaou, Kumar Aditya, Edgar Margffoy, and many others. Some of these contributors are employed by Meta, which has continued to provide significant engineering resources to support this project.) ### Improved error messages {#whatsnew314-improved-error-messages} - The interpreter now provides helpful suggestions when it detects typos in Python keywords. When a word that closely resembles a Python keyword is encountered, the interpreter will suggest the correct keyword in the error message. This feature helps programmers quickly identify and fix common typing mistakes. For example: ``` pycon >>> whille True: ... pass Traceback (most recent call last): File "", line 1 whille True: ^^^^^^ SyntaxError: invalid syntax. Did you mean 'while'? ``` While the feature focuses on the most common cases, some variations of misspellings may still result in regular syntax errors. (Contributed by Pablo Galindo in `132449`{.interpreted-text role="gh"}.) - `elif`{.interpreted-text role="keyword"} statements that follow an `else`{.interpreted-text role="keyword"} block now have a specific error message. (Contributed by Steele Farnsworth in `129902`{.interpreted-text role="gh"}.) ``` pycon >>> if who == "me": ... print("It's me!") ... else: ... print("It's not me!") ... elif who is None: ... print("Who is it?") File "", line 5 elif who is None: ^^^^ SyntaxError: 'elif' block follows an 'else' block ``` - If a statement is passed to the `if_expr`{.interpreted-text role="ref"} after `else`{.interpreted-text role="keyword"}, or one of `pass`{.interpreted-text role="keyword"}, `break`{.interpreted-text role="keyword"}, or `continue`{.interpreted-text role="keyword"} is passed before `if`{.interpreted-text role="keyword"}, then the error message highlights where the `~python-grammar:expression`{.interpreted-text role="token"} is required. (Contributed by Sergey Miryanov in `129515`{.interpreted-text role="gh"}.) ``` pycon >>> x = 1 if True else pass Traceback (most recent call last): File "", line 1 x = 1 if True else pass ^^^^ SyntaxError: expected expression after 'else', but statement is given >>> x = continue if True else break Traceback (most recent call last): File "", line 1 x = continue if True else break ^^^^^^^^ SyntaxError: expected expression before 'if', but statement is given ``` - When incorrectly closed strings are detected, the error message suggests that the string may be intended to be part of the string. (Contributed by Pablo Galindo in `88535`{.interpreted-text role="gh"}.) ``` pycon >>> "The interesting object "The important object" is very important" Traceback (most recent call last): SyntaxError: invalid syntax. Is this intended to be part of the string? ``` - When strings have incompatible prefixes, the error now shows which prefixes are incompatible. (Contributed by Nikita Sobolev in `133197`{.interpreted-text role="gh"}.) ``` pycon >>> ub'abc' File "", line 1 ub'abc' ^^ SyntaxError: 'u' and 'b' prefixes are incompatible ``` - Improved error messages when using `as` with incompatible targets in: - Imports: `import ... as ...` - From imports: `from ... import ... as ...` - Except handlers: `except ... as ...` - Pattern-match cases: `case ... as ...` (Contributed by Nikita Sobolev in `123539`{.interpreted-text role="gh"}, `123562`{.interpreted-text role="gh"}, and `123440`{.interpreted-text role="gh"}.) - Improved error message when trying to add an instance of an unhashable type to a `dict`{.interpreted-text role="class"} or `set`{.interpreted-text role="class"}. (Contributed by CF Bolz-Tereick and Victor Stinner in `132828`{.interpreted-text role="gh"}.) ``` pycon >>> s = set() >>> s.add({'pages': 12, 'grade': 'A'}) Traceback (most recent call last): File "", line 1, in s.add({'pages': 12, 'grade': 'A'}) ~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ TypeError: cannot use 'dict' as a set element (unhashable type: 'dict') >>> d = {} >>> l = [1, 2, 3] >>> d[l] = 12 Traceback (most recent call last): File "", line 1, in d[l] = 12 ~^^^ TypeError: cannot use 'list' as a dict key (unhashable type: 'list') ``` - Improved error message when an object supporting the synchronous context manager protocol is entered using `async with`{.interpreted-text role="keyword"} instead of `with`{.interpreted-text role="keyword"}, and vice versa for the asynchronous context manager protocol. (Contributed by Bénédikt Tran in `128398`{.interpreted-text role="gh"}.) ### `784`{.interpreted-text role="pep"}: Zstandard support in the standard library {#whatsnew314-zstandard} The new `!compression`{.interpreted-text role="mod"} package contains modules `!compression.lzma`{.interpreted-text role="mod"}, `!compression.bz2`{.interpreted-text role="mod"}, `!compression.gzip`{.interpreted-text role="mod"} and `!compression.zlib`{.interpreted-text role="mod"} which re-export the `lzma`{.interpreted-text role="mod"}, `bz2`{.interpreted-text role="mod"}, `gzip`{.interpreted-text role="mod"} and `zlib`{.interpreted-text role="mod"} modules respectively. The new import names under `!compression`{.interpreted-text role="mod"} are the preferred names for importing these compression modules from Python 3.14. However, the existing modules names have not been deprecated. Any deprecation or removal of the existing compression modules will occur no sooner than five years after the release of 3.14. The new `!compression.zstd`{.interpreted-text role="mod"} module provides compression and decompression APIs for the Zstandard format via bindings to [Meta\'s zstd library](https://facebook.github.io/zstd/). Zstandard is a widely adopted, highly efficient, and fast compression format. In addition to the APIs introduced in `!compression.zstd`{.interpreted-text role="mod"}, support for reading and writing Zstandard compressed archives has been added to the `tarfile`{.interpreted-text role="mod"}, `zipfile`{.interpreted-text role="mod"}, and `shutil`{.interpreted-text role="mod"} modules. Here\'s an example of using the new module to compress some data: ``` python from compression import zstd import math data = str(math.pi).encode() * 20 compressed = zstd.compress(data) ratio = len(compressed) / len(data) print(f"Achieved compression ratio of {ratio}") ``` As can be seen, the API is similar to the APIs of the `!lzma`{.interpreted-text role="mod"} and `!bz2`{.interpreted-text role="mod"} modules. (Contributed by Emma Harper Smith, Adam Turner, Gregory P. Smith, Tomas Roun, Victor Stinner, and Rogdham in `132983`{.interpreted-text role="gh"}.) ::: seealso `784`{.interpreted-text role="pep"}. ::: ### Asyncio introspection capabilities {#whatsnew314-asyncio-introspection} Added a new command-line interface to inspect running Python processes using asynchronous tasks, available via `python -m asyncio ps PID` or `python -m asyncio pstree PID`. The `ps` subcommand inspects the given process ID (PID) and displays information about currently running asyncio tasks. It outputs a task table: a flat listing of all tasks, their names, their coroutine stacks, and which tasks are awaiting them. The `pstree` subcommand fetches the same information, but instead renders a visual async call tree, showing coroutine relationships in a hierarchical format. This command is particularly useful for debugging long-running or stuck asynchronous programs. It can help developers quickly identify where a program is blocked, what tasks are pending, and how coroutines are chained together. For example given this code: ``` python import asyncio async def play_track(track): await asyncio.sleep(5) print(f'🎵 Finished: {track}') async def play_album(name, tracks): async with asyncio.TaskGroup() as tg: for track in tracks: tg.create_task(play_track(track), name=track) async def main(): async with asyncio.TaskGroup() as tg: tg.create_task( play_album('Sundowning', ['TNDNBTG', 'Levitate']), name='Sundowning') tg.create_task( play_album('TMBTE', ['DYWTYLM', 'Aqua Regia']), name='TMBTE') if __name__ == '__main__': asyncio.run(main()) ``` Executing the new tool on the running process will yield a table like this: ``` bash python -m asyncio ps 12345 tid task id task name coroutine stack awaiter chain awaiter name awaiter id ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 1935500 0x7fc930c18050 Task-1 TaskGroup._aexit -> TaskGroup.__aexit__ -> main 0x0 1935500 0x7fc930c18230 Sundowning TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050 1935500 0x7fc93173fa50 TMBTE TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050 1935500 0x7fc93173fdf0 TNDNBTG sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230 1935500 0x7fc930d32510 Levitate sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230 1935500 0x7fc930d32890 DYWTYLM sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50 1935500 0x7fc93161ec30 Aqua Regia sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50 ``` or a tree like this: ``` bash python -m asyncio pstree 12345 └── (T) Task-1 └── main example.py:13 └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 ├── (T) Sundowning │ └── album example.py:8 │ └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 │ └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 │ ├── (T) TNDNBTG │ │ └── play example.py:4 │ │ └── sleep Lib/asyncio/tasks.py:702 │ └── (T) Levitate │ └── play example.py:4 │ └── sleep Lib/asyncio/tasks.py:702 └── (T) TMBTE └── album example.py:8 └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 ├── (T) DYWTYLM │ └── play example.py:4 │ └── sleep Lib/asyncio/tasks.py:702 └── (T) Aqua Regia └── play example.py:4 └── sleep Lib/asyncio/tasks.py:702 ``` If a cycle is detected in the async await graph (which could indicate a programming issue), the tool raises an error and lists the cycle paths that prevent tree construction: ``` bash python -m asyncio pstree 12345 ERROR: await-graph contains cycles - cannot print a tree! cycle: Task-2 → Task-3 → Task-2 ``` (Contributed by Pablo Galindo, Łukasz Langa, Yury Selivanov, and Marta Gomez Macias in `91048`{.interpreted-text role="gh"}.) ### Concurrent safe warnings control {#whatsnew314-concurrent-warnings-control} The `warnings.catch_warnings`{.interpreted-text role="class"} context manager will now optionally use a context variable for warning filters. This is enabled by setting the `~sys.flags.context_aware_warnings`{.interpreted-text role="data"} flag, either with the `-X` command-line option or an environment variable. This gives predictable warnings control when using `~warnings.catch_warnings`{.interpreted-text role="class"} combined with multiple threads or asynchronous tasks. The flag defaults to true for the free-threaded build and false for the GIL-enabled build. (Contributed by Neil Schemenauer and Kumar Aditya in `130010`{.interpreted-text role="gh"}.) ## Other language changes - All Windows code pages are now supported as \'cpXXX\' codecs on Windows. (Contributed by Serhiy Storchaka in `123803`{.interpreted-text role="gh"}.) - Implement mixed-mode arithmetic rules combining real and complex numbers as specified by the C standard since C99. (Contributed by Sergey B Kirpichev in `69639`{.interpreted-text role="gh"}.) - More syntax errors are now detected regardless of optimisation and the `-O`{.interpreted-text role="option"} command-line option. This includes writes to `__debug__`, incorrect use of `await`{.interpreted-text role="keyword"}, and asynchronous comprehensions outside asynchronous functions. For example, `python -O -c 'assert (__debug__ := 1)'` or `python -O -c 'assert await 1'` now produce `SyntaxError`{.interpreted-text role="exc"}s. (Contributed by Irit Katriel and Jelle Zijlstra in `122245`{.interpreted-text role="gh"} & `121637`{.interpreted-text role="gh"}.) - When subclassing a pure C type, the C slots for the new type are no longer replaced with a wrapped version on class creation if they are not explicitly overridden in the subclass. (Contributed by Tomasz Pytel in `132284`{.interpreted-text role="gh"}.) ### Built-ins - The `bytes.fromhex`{.interpreted-text role="meth"} and `bytearray.fromhex`{.interpreted-text role="meth"} methods now accept ASCII `bytes`{.interpreted-text role="class"} and `bytes-like objects `{.interpreted-text role="term"}. (Contributed by Daniel Pope in `129349`{.interpreted-text role="gh"}.) - Add class methods `float.from_number`{.interpreted-text role="meth"} and `complex.from_number`{.interpreted-text role="meth"} to convert a number to `float`{.interpreted-text role="class"} or `complex`{.interpreted-text role="class"} type correspondingly. They raise a `TypeError`{.interpreted-text role="exc"} if the argument is not a real number. (Contributed by Serhiy Storchaka in `84978`{.interpreted-text role="gh"}.) - Support underscore and comma as thousands separators in the fractional part for floating-point presentation types of the new-style string formatting (with `format`{.interpreted-text role="func"} or `f-strings`{.interpreted-text role="ref"}). (Contributed by Sergey B Kirpichev in `87790`{.interpreted-text role="gh"}.) - The `int`{.interpreted-text role="func"} function no longer delegates to `~object.__trunc__`{.interpreted-text role="meth"}. Classes that want to support conversion to `!int`{.interpreted-text role="func"} must implement either `~object.__int__`{.interpreted-text role="meth"} or `~object.__index__`{.interpreted-text role="meth"}. (Contributed by Mark Dickinson in `119743`{.interpreted-text role="gh"}.) - The `map`{.interpreted-text role="func"} function now has an optional keyword-only *strict* flag like `zip`{.interpreted-text role="func"} to check that all the iterables are of equal length. (Contributed by Wannes Boeykens in `119793`{.interpreted-text role="gh"}.) - The `memoryview`{.interpreted-text role="class"} type now supports subscription, making it a `generic type`{.interpreted-text role="term"}. (Contributed by Brian Schubert in `126012`{.interpreted-text role="gh"}.) - Using `NotImplemented`{.interpreted-text role="data"} in a boolean context will now raise a `TypeError`{.interpreted-text role="exc"}. This has raised a `DeprecationWarning`{.interpreted-text role="exc"} since Python 3.9. (Contributed by Jelle Zijlstra in `118767`{.interpreted-text role="gh"}.) - Three-argument `pow`{.interpreted-text role="func"} now tries calling `~object.__rpow__`{.interpreted-text role="meth"} if necessary. Previously it was only called in two-argument `!pow`{.interpreted-text role="func"} and the binary power operator. (Contributed by Serhiy Storchaka in `130104`{.interpreted-text role="gh"}.) - `super`{.interpreted-text role="class"} objects are now `copyable `{.interpreted-text role="mod"} and `pickleable `{.interpreted-text role="mod"}. (Contributed by Serhiy Storchaka in `125767`{.interpreted-text role="gh"}.) ### Command line and environment - The import time flag can now track modules that are already loaded (\'cached\'), via the new `-X importtime=2 <-X>`{.interpreted-text role="option"}. When such a module is imported, the `self` and `cumulative` times are replaced by the string `cached`. Values above `2` for `-X importtime` are now reserved for future use. (Contributed by Noah Kim and Adam Turner in `118655`{.interpreted-text role="gh"}.) - The command-line option `-c`{.interpreted-text role="option"} now automatically dedents its code argument before execution. The auto-dedentation behavior mirrors `textwrap.dedent`{.interpreted-text role="func"}. (Contributed by Jon Crall and Steven Sun in `103998`{.interpreted-text role="gh"}.) - `!-J`{.interpreted-text role="option"} is no longer a reserved flag for [Jython](https://www.jython.org/), and now has no special meaning. (Contributed by Adam Turner in `133336`{.interpreted-text role="gh"}.) ### PEP 758: Allow `except` and `except*` expressions without brackets {#whatsnew314-bracketless-except} The `except`{.interpreted-text role="keyword"} and `except* `{.interpreted-text role="keyword"} expressions now allow brackets to be omitted when there are multiple exception types and the `as` clause is not used. For example: ``` python try: connect_to_server() except TimeoutError, ConnectionRefusedError: print('The network has ceased to be!') ``` (Contributed by Pablo Galindo and Brett Cannon in `758`{.interpreted-text role="pep"} and `131831`{.interpreted-text role="gh"}.) ### PEP 765: Control flow in `finally`{.interpreted-text role="keyword"} blocks {#whatsnew314-finally-syntaxwarning} The compiler now emits a `SyntaxWarning`{.interpreted-text role="exc"} when a `return`{.interpreted-text role="keyword"}, `break`{.interpreted-text role="keyword"}, or `continue`{.interpreted-text role="keyword"} statement have the effect of leaving a `finally`{.interpreted-text role="keyword"} block. This change is specified in `765`{.interpreted-text role="pep"}. In situations where this change is inconvenient (such as those where the warnings are redundant due to code linting), the `warning filter `{.interpreted-text role="ref"} can be used to turn off all syntax warnings by adding `ignore::SyntaxWarning` as a filter. This can be specified in combination with a filter that converts other warnings to errors (for example, passing `-Werror -Wignore::SyntaxWarning` as CLI options, or setting `PYTHONWARNINGS=error,ignore::SyntaxWarning`). Note that applying such a filter at runtime using the `warnings`{.interpreted-text role="mod"} module will only suppress the warning in code that is compiled *after* the filter is adjusted. Code that is compiled prior to the filter adjustment (for example, when a module is imported) will still emit the syntax warning. (Contributed by Irit Katriel in `130080`{.interpreted-text role="gh"}.) ### Incremental garbage collection {#whatsnew314-incremental-gc} The cycle garbage collector is now incremental. This means that maximum pause times are reduced by an order of magnitude or more for larger heaps. There are now only two generations: young and old. When `gc.collect`{.interpreted-text role="func"} is not called directly, the GC is invoked a little less frequently. When invoked, it collects the young generation and an increment of the old generation, instead of collecting one or more generations. The behavior of `!gc.collect`{.interpreted-text role="func"} changes slightly: - `gc.collect(1)`: Performs an increment of garbage collection, rather than collecting generation 1. - Other calls to `!gc.collect`{.interpreted-text role="func"} are unchanged. (Contributed by Mark Shannon in `108362`{.interpreted-text role="gh"}.) ### Default interactive shell ::: {#whatsnew314-pyrepl-highlighting} - The default `interactive`{.interpreted-text role="term"} shell now highlights Python syntax. The feature is enabled by default, save if `PYTHON_BASIC_REPL`{.interpreted-text role="envvar"} or any other environment variable that disables colour is set. See `using-on-controlling-color`{.interpreted-text role="ref"} for details. The default color theme for syntax highlighting strives for good contrast and exclusively uses the 4-bit VGA standard ANSI color codes for maximum compatibility. The theme can be customized using an experimental API `!_colorize.set_theme`{.interpreted-text role="func"}. This can be called interactively or in the `PYTHONSTARTUP`{.interpreted-text role="envvar"} script. Note that this function has no stability guarantees, and may change or be removed. (Contributed by Łukasz Langa in `131507`{.interpreted-text role="gh"}.) - The default `interactive`{.interpreted-text role="term"} shell now supports import auto-completion. This means that typing `import co` and pressing ``{.interpreted-text role="kbd"} will suggest modules starting with `co`. Similarly, typing `from concurrent import i` will suggest submodules of `concurrent` starting with `i`. Note that autocompletion of module attributes is not currently supported. (Contributed by Tomas Roun in `69605`{.interpreted-text role="gh"}.) ::: ## New modules - `annotationlib`{.interpreted-text role="mod"}: For introspecting `annotations `{.interpreted-text role="term"}. See `PEP 749 `{.interpreted-text role="ref"} for more details. (Contributed by Jelle Zijlstra in `119180`{.interpreted-text role="gh"}.) - `compression`{.interpreted-text role="mod"} (including `compression.zstd`{.interpreted-text role="mod"}): A package for compression-related modules, including a new module to support the Zstandard compression format. See `PEP 784 `{.interpreted-text role="ref"} for more details. (Contributed by Emma Harper Smith, Adam Turner, Gregory P. Smith, Tomas Roun, Victor Stinner, and Rogdham in `132983`{.interpreted-text role="gh"}.) - `concurrent.interpreters`{.interpreted-text role="mod"}: Support for multiple interpreters in the standard library. See `PEP 734 `{.interpreted-text role="ref"} for more details. (Contributed by Eric Snow in `134939`{.interpreted-text role="gh"}.) - `string.templatelib`{.interpreted-text role="mod"}: Support for template string literals (t-strings). See `PEP 750 `{.interpreted-text role="ref"} for more details. (Contributed by Jim Baker, Guido van Rossum, Paul Everitt, Koudai Aono, Lysandros Nikolaou, Dave Peck, Adam Turner, Jelle Zijlstra, Bénédikt Tran, and Pablo Galindo Salgado in `132661`{.interpreted-text role="gh"}.) ## Improved modules ### argparse - The default value of the `program name `{.interpreted-text role="ref"} for `argparse.ArgumentParser`{.interpreted-text role="class"} now reflects the way the Python interpreter was instructed to find the `__main__` module code. (Contributed by Serhiy Storchaka and Alyssa Coghlan in `66436`{.interpreted-text role="gh"}.) - Introduced the optional *suggest_on_error* parameter to `argparse.ArgumentParser`{.interpreted-text role="class"}, enabling suggestions for argument choices and subparser names if mistyped by the user. (Contributed by Savannah Ostrowski in `124456`{.interpreted-text role="gh"}.) - Enable color for help text, which can be disabled with the optional *color* parameter to `argparse.ArgumentParser`{.interpreted-text role="class"}. This can also be controlled by `environment variables `{.interpreted-text role="ref"}. (Contributed by Hugo van Kemenade in `130645`{.interpreted-text role="gh"}.) ### ast - Add `~ast.compare`{.interpreted-text role="func"}, a function for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in `60191`{.interpreted-text role="gh"}.) - Add support for `copy.replace`{.interpreted-text role="func"} for AST nodes. (Contributed by Bénédikt Tran in `121141`{.interpreted-text role="gh"}.) - Docstrings are now removed from an optimized AST in optimization level 2. (Contributed by Irit Katriel in `123958`{.interpreted-text role="gh"}.) - The `repr`{.interpreted-text role="func"} output for AST nodes now includes more information. (Contributed by Tomas Roun in `116022`{.interpreted-text role="gh"}.) - When called with an AST as input, the `~ast.parse`{.interpreted-text role="func"} function now always verifies that the root node type is appropriate. (Contributed by Irit Katriel in `130139`{.interpreted-text role="gh"}.) - Add new options to the command-line interface: `--feature-version `{.interpreted-text role="option"}, `--optimize `{.interpreted-text role="option"}, and `--show-empty `{.interpreted-text role="option"}. (Contributed by Semyon Moroz in `133367`{.interpreted-text role="gh"}.) ### asyncio - The function and methods named `!create_task`{.interpreted-text role="func"} now take an arbitrary list of keyword arguments. All keyword arguments are passed to the `~asyncio.Task`{.interpreted-text role="class"} constructor or the custom task factory. (See `~asyncio.loop.set_task_factory`{.interpreted-text role="meth"} for details.) The `name` and `context` keyword arguments are no longer special; the name should now be set using the `name` keyword argument of the factory, and `context` may be `None`. This affects the following function and methods: `asyncio.create_task`{.interpreted-text role="meth"}, `asyncio.loop.create_task`{.interpreted-text role="meth"}, `asyncio.TaskGroup.create_task`{.interpreted-text role="meth"}. (Contributed by Thomas Grainger in `128307`{.interpreted-text role="gh"}.) - There are two new utility functions for introspecting and printing a program\'s call graph: `~asyncio.capture_call_graph`{.interpreted-text role="func"} and `~asyncio.print_call_graph`{.interpreted-text role="func"}. See `Asyncio introspection capabilities `{.interpreted-text role="ref"} for more details. (Contributed by Yury Selivanov, Pablo Galindo Salgado, and Łukasz Langa in `91048`{.interpreted-text role="gh"}.) ### calendar ::: {#whatsnew314-color-calendar} - By default, today\'s date is highlighted in color in `calendar`{.interpreted-text role="mod"}\'s `command-line `{.interpreted-text role="ref"} text output. This can be controlled by `environment variables `{.interpreted-text role="ref"}. (Contributed by Hugo van Kemenade in `128317`{.interpreted-text role="gh"}.) ::: ### concurrent.futures ::: {#whatsnew314-concurrent-futures-interp-pool} - Add a new executor class, `~concurrent.futures.InterpreterPoolExecutor`{.interpreted-text role="class"}, which exposes multiple Python interpreters in the same process (\'subinterpreters\') to Python code. This uses a pool of independent Python interpreters to execute calls asynchronously. This is separate from the new `~concurrent.interpreters`{.interpreted-text role="mod"} module introduced by `PEP 734 `{.interpreted-text role="ref"}. (Contributed by Eric Snow in `124548`{.interpreted-text role="gh"}.) ::: ::: {#whatsnew314-concurrent-futures-start-method} - On Unix platforms other than macOS, `'forkserver' `{.interpreted-text role="ref"} is now the default `start method `{.interpreted-text role="ref"} for `~concurrent.futures.ProcessPoolExecutor`{.interpreted-text role="class"} (replacing `'fork' `{.interpreted-text role="ref"}). This change does not affect Windows or macOS, where `'spawn' `{.interpreted-text role="ref"} remains the default start method. If the threading incompatible *fork* method is required, you must explicitly request it by supplying a multiprocessing context *mp_context* to `~concurrent.futures.ProcessPoolExecutor`{.interpreted-text role="class"}. See `forkserver restrictions `{.interpreted-text role="ref"} for information and differences with the *fork* method and how this change may affect existing code with mutable global shared variables and/or shared objects that can not be automatically `pickled `{.interpreted-text role="mod"}. (Contributed by Gregory P. Smith in `84559`{.interpreted-text role="gh"}.) - Add two new methods to `~concurrent.futures.ProcessPoolExecutor`{.interpreted-text role="class"}, `~concurrent.futures.ProcessPoolExecutor.terminate_workers`{.interpreted-text role="meth"} and `~concurrent.futures.ProcessPoolExecutor.kill_workers`{.interpreted-text role="meth"}, as ways to terminate or kill all living worker processes in the given pool. (Contributed by Charles Machalow in `130849`{.interpreted-text role="gh"}.) - Add the optional *buffersize* parameter to `Executor.map `{.interpreted-text role="meth"} to limit the number of submitted tasks whose results have not yet been yielded. If the buffer is full, iteration over the *iterables* pauses until a result is yielded from the buffer. (Contributed by Enzo Bonnal and Josh Rosenberg in `74028`{.interpreted-text role="gh"}.) ::: ### configparser - `!configparser`{.interpreted-text role="mod"} will no longer write config files it cannot read, to improve security. Attempting to `~configparser.ConfigParser.write`{.interpreted-text role="meth"} keys containing delimiters or beginning with the section header pattern will raise an `~configparser.InvalidWriteError`{.interpreted-text role="class"}. (Contributed by Jacob Lincoln in `129270`{.interpreted-text role="gh"}.) ### contextvars - Support the `context manager`{.interpreted-text role="term"} protocol for `~contextvars.Token`{.interpreted-text role="class"} objects. (Contributed by Andrew Svetlov in `129889`{.interpreted-text role="gh"}.) ### ctypes - The layout of `bit fields `{.interpreted-text role="ref"} in `~ctypes.Structure`{.interpreted-text role="class"} and `~ctypes.Union`{.interpreted-text role="class"} objects is now a closer match to platform defaults (GCC/Clang or MSVC). In particular, fields no longer overlap. (Contributed by Matthias Görgens in `97702`{.interpreted-text role="gh"}.) - The `.Structure._layout_`{.interpreted-text role="attr"} class attribute can now be set to help match a non-default ABI. (Contributed by Petr Viktorin in `97702`{.interpreted-text role="gh"}.) - The class of `~ctypes.Structure`{.interpreted-text role="class"}/`~ctypes.Union`{.interpreted-text role="class"} field descriptors is now available as `~ctypes.CField`{.interpreted-text role="class"}, and has new attributes to aid debugging and introspection. (Contributed by Petr Viktorin in `128715`{.interpreted-text role="gh"}.) - On Windows, the `~ctypes.COMError`{.interpreted-text role="exc"} exception is now public. (Contributed by Jun Komoda in `126686`{.interpreted-text role="gh"}.) - On Windows, the `~ctypes.CopyComPointer`{.interpreted-text role="func"} function is now public. (Contributed by Jun Komoda in `127275`{.interpreted-text role="gh"}.) - Add `~ctypes.memoryview_at`{.interpreted-text role="func"}, a function to create a `memoryview`{.interpreted-text role="class"} object that refers to the supplied pointer and length. This works like `ctypes.string_at`{.interpreted-text role="func"} except it avoids a buffer copy, and is typically useful when implementing pure Python callback functions that are passed dynamically-sized buffers. (Contributed by Rian Hunter in `112018`{.interpreted-text role="gh"}.) - Complex types, `~ctypes.c_float_complex`{.interpreted-text role="class"}, `~ctypes.c_double_complex`{.interpreted-text role="class"}, and `~ctypes.c_longdouble_complex`{.interpreted-text role="class"}, are now available if both the compiler and the `libffi` library support complex C types. (Contributed by Sergey B Kirpichev in `61103`{.interpreted-text role="gh"}.) - Add `ctypes.util.dllist`{.interpreted-text role="func"} for listing the shared libraries loaded by the current process. (Contributed by Brian Ward in `119349`{.interpreted-text role="gh"}.) - Move `ctypes.POINTER`{.interpreted-text role="func"} types cache from a global internal cache (`_pointer_type_cache`) to the `_CData.__pointer_type__ `{.interpreted-text role="attr"} attribute of the corresponding `!ctypes`{.interpreted-text role="mod"} types. This will stop the cache from growing without limits in some situations. (Contributed by Sergey Miryanov in `100926`{.interpreted-text role="gh"}.) - The `~ctypes.py_object`{.interpreted-text role="class"} type now supports subscription, making it a `generic type`{.interpreted-text role="term"}. (Contributed by Brian Schubert in `132168`{.interpreted-text role="gh"}.) - `!ctypes`{.interpreted-text role="mod"} now supports `free-threading builds `{.interpreted-text role="term"}. (Contributed by Kumar Aditya and Peter Bierma in `127945`{.interpreted-text role="gh"}.) ### curses - Add the `~curses.assume_default_colors`{.interpreted-text role="func"} function, a refinement of the `~curses.use_default_colors`{.interpreted-text role="func"} function which allows changing the color pair `0`. (Contributed by Serhiy Storchaka in `133139`{.interpreted-text role="gh"}.) ### datetime - Add the `~datetime.date.strptime`{.interpreted-text role="meth"} method to the `datetime.date`{.interpreted-text role="class"} and `datetime.time`{.interpreted-text role="class"} classes. (Contributed by Wannes Boeykens in `41431`{.interpreted-text role="gh"}.) ### decimal - Add `.Decimal.from_number`{.interpreted-text role="meth"} as an alternative constructor for `~decimal.Decimal`{.interpreted-text role="class"}. (Contributed by Serhiy Storchaka in `121798`{.interpreted-text role="gh"}.) - Expose `~decimal.IEEEContext`{.interpreted-text role="func"} to support creation of contexts corresponding to the IEEE 754 (2008) decimal interchange formats. (Contributed by Sergey B Kirpichev in `53032`{.interpreted-text role="gh"}.) ### difflib - Comparison pages with highlighted changes generated by the `~difflib.HtmlDiff`{.interpreted-text role="class"} class now support \'dark mode\'. (Contributed by Jiahao Li in `129939`{.interpreted-text role="gh"}.) ### dis - Add support for rendering full source location information of `instructions `{.interpreted-text role="class"}, rather than only the line number. This feature is added to the following interfaces via the *show_positions* keyword argument: - `dis.Bytecode`{.interpreted-text role="class"} - `dis.dis`{.interpreted-text role="func"} - `dis.distb`{.interpreted-text role="func"} - `dis.disassemble`{.interpreted-text role="func"} This feature is also exposed via `dis --show-positions`{.interpreted-text role="option"}. (Contributed by Bénédikt Tran in `123165`{.interpreted-text role="gh"}.) - Add the `dis --specialized`{.interpreted-text role="option"} command-line option to show specialized bytecode. (Contributed by Bénédikt Tran in `127413`{.interpreted-text role="gh"}.) ### errno - Add the `~errno.EHWPOISON`{.interpreted-text role="data"} error code constant. (Contributed by James Roy in `126585`{.interpreted-text role="gh"}.) ### faulthandler - Add support for printing the C stack trace on systems that `support it `{.interpreted-text role="ref"} via the new `~faulthandler.dump_c_stack`{.interpreted-text role="func"} function or via the *c_stack* argument in `faulthandler.enable`{.interpreted-text role="func"}. (Contributed by Peter Bierma in `127604`{.interpreted-text role="gh"}.) ### fnmatch - Add `~fnmatch.filterfalse`{.interpreted-text role="func"}, a function to reject names matching a given pattern. (Contributed by Bénédikt Tran in `74598`{.interpreted-text role="gh"}.) ### fractions - A `~fractions.Fraction`{.interpreted-text role="class"} object may now be constructed from any object with the `!as_integer_ratio`{.interpreted-text role="meth"} method. (Contributed by Serhiy Storchaka in `82017`{.interpreted-text role="gh"}.) - Add `.Fraction.from_number`{.interpreted-text role="meth"} as an alternative constructor for `~fractions.Fraction`{.interpreted-text role="class"}. (Contributed by Serhiy Storchaka in `121797`{.interpreted-text role="gh"}.) ### functools - Add the `~functools.Placeholder`{.interpreted-text role="data"} sentinel. This may be used with the `~functools.partial`{.interpreted-text role="func"} or `~functools.partialmethod`{.interpreted-text role="func"} functions to reserve a place for positional arguments in the returned `partial object `{.interpreted-text role="ref"}. (Contributed by Dominykas Grigonis in `119127`{.interpreted-text role="gh"}.) - Allow the *initial* parameter of `~functools.reduce`{.interpreted-text role="func"} to be passed as a keyword argument. (Contributed by Sayandip Dutta in `125916`{.interpreted-text role="gh"}.) ### getopt - Add support for options with optional arguments. (Contributed by Serhiy Storchaka in `126374`{.interpreted-text role="gh"}.) - Add support for returning intermixed options and non-option arguments in order. (Contributed by Serhiy Storchaka in `126390`{.interpreted-text role="gh"}.) ### getpass - Support keyboard feedback in the `~getpass.getpass`{.interpreted-text role="func"} function via the keyword-only optional argument *echo_char*. Placeholder characters are rendered whenever a character is entered, and removed when a character is deleted. (Contributed by Semyon Moroz in `77065`{.interpreted-text role="gh"}.) ### graphlib - Allow `.TopologicalSorter.prepare`{.interpreted-text role="meth"} to be called more than once as long as sorting has not started. (Contributed by Daniel Pope in `130914`{.interpreted-text role="gh"}.) ### heapq - The `!heapq`{.interpreted-text role="mod"} module has improved support for working with max-heaps, via the following new functions: - `~heapq.heapify_max`{.interpreted-text role="func"} - `~heapq.heappush_max`{.interpreted-text role="func"} - `~heapq.heappop_max`{.interpreted-text role="func"} - `~heapq.heapreplace_max`{.interpreted-text role="func"} - `~heapq.heappushpop_max`{.interpreted-text role="func"} ### hmac - Add a built-in implementation for HMAC (`2104`{.interpreted-text role="rfc"}) using formally verified code from the [HACL\*](https://github.com/hacl-star/hacl-star/) project. This implementation is used as a fallback when the OpenSSL implementation of HMAC is not available. (Contributed by Bénédikt Tran in `99108`{.interpreted-text role="gh"}.) ### http - Directory lists and error pages generated by the `http.server`{.interpreted-text role="mod"} module allow the browser to apply its default dark mode. (Contributed by Yorik Hansen in `123430`{.interpreted-text role="gh"}.) - The `http.server`{.interpreted-text role="mod"} module now supports serving over HTTPS using the `http.server.HTTPSServer`{.interpreted-text role="class"} class. This functionality is exposed by the command-line interface (`python -m http.server`) through the following options: - `--tls-cert \ `{.interpreted-text role="option"}: Path to the TLS certificate file. - `--tls-key \ `{.interpreted-text role="option"}: Optional path to the private key file. - `--tls-password-file \ `{.interpreted-text role="option"}: Optional path to the password file for the private key. (Contributed by Semyon Moroz in `85162`{.interpreted-text role="gh"}.) ### imaplib - Add `.IMAP4.idle`{.interpreted-text role="meth"}, implementing the IMAP4 `IDLE` command as defined in `2177`{.interpreted-text role="rfc"}. (Contributed by Forest in `55454`{.interpreted-text role="gh"}.) ### inspect - `~inspect.signature`{.interpreted-text role="func"} takes a new argument *annotation_format* to control the `annotationlib.Format`{.interpreted-text role="class"} used for representing annotations. (Contributed by Jelle Zijlstra in `101552`{.interpreted-text role="gh"}.) - `.Signature.format`{.interpreted-text role="meth"} takes a new argument *unquote_annotations*. If true, string `annotations `{.interpreted-text role="term"} are displayed without surrounding quotes. (Contributed by Jelle Zijlstra in `101552`{.interpreted-text role="gh"}.) - Add function `~inspect.ispackage`{.interpreted-text role="func"} to determine whether an object is a `package`{.interpreted-text role="term"} or not. (Contributed by Zhikang Yan in `125634`{.interpreted-text role="gh"}.) ### io - Reading text from a non-blocking stream with `read` may now raise a `BlockingIOError`{.interpreted-text role="exc"} if the operation cannot immediately return bytes. (Contributed by Giovanni Siragusa in `109523`{.interpreted-text role="gh"}.) - Add the `~io.Reader`{.interpreted-text role="class"} and `~io.Writer`{.interpreted-text role="class"} protocols as simpler alternatives to the pseudo-protocols `typing.IO`{.interpreted-text role="class"}, `typing.TextIO`{.interpreted-text role="class"}, and `typing.BinaryIO`{.interpreted-text role="class"}. (Contributed by Sebastian Rittau in `127648`{.interpreted-text role="gh"}.) ### json - Add exception notes for JSON serialization errors that allow identifying the source of the error. (Contributed by Serhiy Storchaka in `122163`{.interpreted-text role="gh"}.) - Allow using the `json`{.interpreted-text role="mod"} module as a script using the `-m`{.interpreted-text role="option"} switch: `python -m json`{.interpreted-text role="program"}. This is now preferred to `python -m json.tool`{.interpreted-text role="program"}, which is `soft deprecated`{.interpreted-text role="term"}. See the `JSON command-line interface `{.interpreted-text role="ref"} documentation. (Contributed by Trey Hunner in `122873`{.interpreted-text role="gh"}.) - By default, the output of the `JSON command-line interface `{.interpreted-text role="ref"} is highlighted in color. This can be controlled by `environment variables `{.interpreted-text role="ref"}. (Contributed by Tomas Roun in `131952`{.interpreted-text role="gh"}.) ### linecache - `~linecache.getline`{.interpreted-text role="func"} can now retrieve source code for frozen modules. (Contributed by Tian Gao in `131638`{.interpreted-text role="gh"}.) ### logging.handlers - `~logging.handlers.QueueListener`{.interpreted-text role="class"} objects now support the `context manager`{.interpreted-text role="term"} protocol. (Contributed by Charles Machalow in `132106`{.interpreted-text role="gh"}.) - `QueueListener.start `{.interpreted-text role="meth"} now raises a `RuntimeError`{.interpreted-text role="exc"} if the listener is already started. (Contributed by Charles Machalow in `132106`{.interpreted-text role="gh"}.) ### math - Added more detailed error messages for domain errors in the module. (Contributed by Charlie Zhao and Sergey B Kirpichev in `101410`{.interpreted-text role="gh"}.) ### mimetypes - Add a public `command-line `{.interpreted-text role="ref"} for the module, invoked via `python -m mimetypes`{.interpreted-text role="program"}. (Contributed by Oleg Iarygin and Hugo van Kemenade in `93096`{.interpreted-text role="gh"}.) - Add several new MIME types based on RFCs and common usage: **Microsoft and `8081`{.interpreted-text role="rfc"} MIME types for fonts** - Embedded OpenType: `application/vnd.ms-fontobject` - OpenType Layout (OTF) `font/otf` - TrueType: `font/ttf` - WOFF 1.0 `font/woff` - WOFF 2.0 `font/woff2` **`9559`{.interpreted-text role="rfc"} MIME types for Matroska audiovisual data container structures** - audio with no video: `audio/matroska` (`.mka`) - video: `video/matroska` (`.mkv`) - stereoscopic video: `video/matroska-3d` (`.mk3d`) **Images with RFCs** - `1494`{.interpreted-text role="rfc"}: CCITT Group 3 (`.g3`) - `3362`{.interpreted-text role="rfc"}: Real-time Facsimile, T.38 (`.t38`) - `3745`{.interpreted-text role="rfc"}: JPEG 2000 (`.jp2`), extension (`.jpx`) and compound (`.jpm`) - `3950`{.interpreted-text role="rfc"}: Tag Image File Format Fax eXtended, TIFF-FX (`.tfx`) - `4047`{.interpreted-text role="rfc"}: Flexible Image Transport System (`.fits`) - `7903`{.interpreted-text role="rfc"}: Enhanced Metafile (`.emf`) and Windows Metafile (`.wmf`) **Other MIME type additions and changes** - `2361`{.interpreted-text role="rfc"}: Change type for `.avi` to `video/vnd.avi` and for `.wav` to `audio/vnd.wave` - `4337`{.interpreted-text role="rfc"}: Add MPEG-4 `audio/mp4` (`.m4a`) - `5334`{.interpreted-text role="rfc"}: Add Ogg media (`.oga`, `.ogg` and `.ogx`) - `6713`{.interpreted-text role="rfc"}: Add gzip `application/gzip` (`.gz`) - `9639`{.interpreted-text role="rfc"}: Add FLAC `audio/flac` (`.flac`) - `9512`{.interpreted-text role="rfc"} `application/yaml` MIME type for YAML files (`.yaml` and `.yml`) - Add 7z `application/x-7z-compressed` (`.7z`) - Add Android Package `application/vnd.android.package-archive` (`.apk`) when not strict - Add deb `application/x-debian-package` (`.deb`) - Add glTF binary `model/gltf-binary` (`.glb`) - Add glTF JSON/ASCII `model/gltf+json` (`.gltf`) - Add M4V `video/x-m4v` (`.m4v`) - Add PHP `application/x-httpd-php` (`.php`) - Add RAR `application/vnd.rar` (`.rar`) - Add RPM `application/x-rpm` (`.rpm`) - Add STL `model/stl` (`.stl`) - Add Windows Media Video `video/x-ms-wmv` (`.wmv`) - De facto: Add WebM `audio/webm` (`.weba`) - [ECMA-376](https://ecma-international.org/publications-and-standards/standards/ecma-376/): Add `.docx`, `.pptx` and `.xlsx` types - [OASIS](https://docs.oasis-open.org/office/v1.2/cs01/OpenDocument-v1.2-cs01-part1.html#Appendix_C): Add OpenDocument `.odg`, `.odp`, `.ods` and `.odt` types - [W3C](https://www.w3.org/TR/epub-33/#app-media-type): Add EPUB `application/epub+zip` (`.epub`) (Contributed by Sahil Prajapati and Hugo van Kemenade in `84852`{.interpreted-text role="gh"}, by Sasha \"Nelie\" Chernykh and Hugo van Kemenade in `132056`{.interpreted-text role="gh"}, and by Hugo van Kemenade in `89416`{.interpreted-text role="gh"}, `85957`{.interpreted-text role="gh"}, and `129965`{.interpreted-text role="gh"}.) ### multiprocessing ::: {#whatsnew314-multiprocessing-start-method} - On Unix platforms other than macOS, `'forkserver' `{.interpreted-text role="ref"} is now the default `start method `{.interpreted-text role="ref"} (replacing `'fork' `{.interpreted-text role="ref"}). This change does not affect Windows or macOS, where `'spawn' `{.interpreted-text role="ref"} remains the default start method. If the threading incompatible *fork* method is required, you must explicitly request it via a context from `~multiprocessing.get_context`{.interpreted-text role="func"} (preferred) or change the default via `~multiprocessing.set_start_method`{.interpreted-text role="func"}. See `forkserver restrictions `{.interpreted-text role="ref"} for information and differences with the *fork* method and how this change may affect existing code with mutable global shared variables and/or shared objects that can not be automatically `pickled `{.interpreted-text role="mod"}. (Contributed by Gregory P. Smith in `84559`{.interpreted-text role="gh"}.) - `multiprocessing`{.interpreted-text role="mod"}\'s `'forkserver'` start method now authenticates its control socket to avoid solely relying on filesystem permissions to restrict what other processes could cause the forkserver to spawn workers and run code. (Contributed by Gregory P. Smith for `97514`{.interpreted-text role="gh"}.) - The `multiprocessing proxy objects `{.interpreted-text role="ref"} for *list* and *dict* types gain previously overlooked missing methods: > - `!clear`{.interpreted-text role="meth"} and `!copy`{.interpreted-text role="meth"} for proxies of `list`{.interpreted-text role="class"} > - `~dict.fromkeys`{.interpreted-text role="meth"}, `reversed(d)`, `d | {}`, `{} | d`, `d |= {'b': 2}` for proxies of `dict`{.interpreted-text role="class"} (Contributed by Roy Hyunjin Han for `103134`{.interpreted-text role="gh"}.) - Add support for shared `set`{.interpreted-text role="class"} objects via `.SyncManager.set`{.interpreted-text role="meth"}. The `set`{.interpreted-text role="func"} in `~multiprocessing.Manager`{.interpreted-text role="func"} method is now available. (Contributed by Mingyu Park in `129949`{.interpreted-text role="gh"}.) - Add the `~multiprocessing.Process.interrupt`{.interpreted-text role="meth"} to `multiprocessing.Process`{.interpreted-text role="class"} objects, which terminates the child process by sending `~signal.SIGINT`{.interpreted-text role="py:const"}. This enables `finally`{.interpreted-text role="keyword"} clauses to print a stack trace for the terminated process. (Contributed by Artem Pulkin in `131913`{.interpreted-text role="gh"}.) ::: ### operator - Add `~operator.is_none`{.interpreted-text role="func"} and `~operator.is_not_none`{.interpreted-text role="func"} as a pair of functions, such that `operator.is_none(obj)` is equivalent to `obj is None` and `operator.is_not_none(obj)` is equivalent to `obj is not None`. (Contributed by Raymond Hettinger and Nico Mexis in `115808`{.interpreted-text role="gh"}.) ### os - Add the `~os.reload_environ`{.interpreted-text role="func"} function to update `os.environ`{.interpreted-text role="data"} and `os.environb`{.interpreted-text role="data"} with changes to the environment made by `os.putenv`{.interpreted-text role="func"}, by `os.unsetenv`{.interpreted-text role="func"}, or made outside Python in the same process. (Contributed by Victor Stinner in `120057`{.interpreted-text role="gh"}.) - Add the `~os.SCHED_DEADLINE`{.interpreted-text role="data"} and `~os.SCHED_NORMAL`{.interpreted-text role="data"} constants to the `!os`{.interpreted-text role="mod"} module. (Contributed by James Roy in `127688`{.interpreted-text role="gh"}.) - Add the `~os.readinto`{.interpreted-text role="func"} function to read into a `buffer object `{.interpreted-text role="ref"} from a file descriptor. (Contributed by Cody Maloney in `129205`{.interpreted-text role="gh"}.) ### os.path - The *strict* parameter to `~os.path.realpath`{.interpreted-text role="func"} accepts a new value, `~os.path.ALLOW_MISSING`{.interpreted-text role="data"}. If used, errors other than `FileNotFoundError`{.interpreted-text role="exc"} will be re-raised; the resulting path can be missing but it will be free of symlinks. (Contributed by Petr Viktorin for `2025-4517`{.interpreted-text role="cve"}.) ### pathlib - Add methods to `pathlib.Path`{.interpreted-text role="class"} to recursively copy or move files and directories: - `~pathlib.Path.copy`{.interpreted-text role="meth"} copies a file or directory tree to a destination. - `~pathlib.Path.copy_into`{.interpreted-text role="meth"} copies *into* a destination directory. - `~pathlib.Path.move`{.interpreted-text role="meth"} moves a file or directory tree to a destination. - `~pathlib.Path.move_into`{.interpreted-text role="meth"} moves *into* a destination directory. (Contributed by Barney Gale in `73991`{.interpreted-text role="gh"}.) - Add the `~pathlib.Path.info`{.interpreted-text role="attr"} attribute, which stores an object implementing the new `pathlib.types.PathInfo`{.interpreted-text role="class"} protocol. The object supports querying the file type and internally caching `~os.stat`{.interpreted-text role="func"} results. Path objects generated by `~pathlib.Path.iterdir`{.interpreted-text role="meth"} are initialized with file type information gleaned from scanning the parent directory. (Contributed by Barney Gale in `125413`{.interpreted-text role="gh"}.) ### pdb - The `pdb`{.interpreted-text role="mod"} module now supports remote attaching to a running Python process using a new `-p PID `{.interpreted-text role="option"} command-line option: ``` sh python -m pdb -p 1234 ``` This will connect to the Python process with the given PID and allow you to debug it interactively. Notice that due to how the Python interpreter works attaching to a remote process that is blocked in a system call or waiting for I/O will only work once the next bytecode instruction is executed or when the process receives a signal. This feature uses `PEP 768 `{.interpreted-text role="ref"} and the new `sys.remote_exec`{.interpreted-text role="func"} function to attach to the remote process and send the PDB commands to it. (Contributed by Matt Wozniski and Pablo Galindo in `131591`{.interpreted-text role="gh"}.) - Hardcoded breakpoints (`breakpoint`{.interpreted-text role="func"} and `~pdb.set_trace`{.interpreted-text role="func"}) now reuse the most recent `~pdb.Pdb`{.interpreted-text role="class"} instance that calls `~pdb.Pdb.set_trace`{.interpreted-text role="meth"}, instead of creating a new one each time. As a result, all the instance specific data like `display`{.interpreted-text role="pdbcmd"} and `commands`{.interpreted-text role="pdbcmd"} are preserved across hardcoded breakpoints. (Contributed by Tian Gao in `121450`{.interpreted-text role="gh"}.) - Add a new argument *mode* to `pdb.Pdb`{.interpreted-text role="class"}. Disable the `restart` command when `pdb`{.interpreted-text role="mod"} is in `inline` mode. (Contributed by Tian Gao in `123757`{.interpreted-text role="gh"}.) - A confirmation prompt will be shown when the user tries to quit `pdb`{.interpreted-text role="mod"} in `inline` mode. `y`, `Y`, `` or `EOF` will confirm the quit and call `sys.exit`{.interpreted-text role="func"}, instead of raising `bdb.BdbQuit`{.interpreted-text role="exc"}. (Contributed by Tian Gao in `124704`{.interpreted-text role="gh"}.) - Inline breakpoints like `breakpoint`{.interpreted-text role="func"} or `pdb.set_trace`{.interpreted-text role="func"} will always stop the program at calling frame, ignoring the `skip` pattern (if any). (Contributed by Tian Gao in `130493`{.interpreted-text role="gh"}.) - `` at the beginning of the line in `pdb`{.interpreted-text role="mod"} multi-line input will fill in a 4-space indentation now, instead of inserting a `\t` character. (Contributed by Tian Gao in `130471`{.interpreted-text role="gh"}.) - Auto-indent is introduced in `pdb`{.interpreted-text role="mod"} multi-line input. It will either keep the indentation of the last line or insert a 4-space indentation when it detects a new code block. (Contributed by Tian Gao in `133350`{.interpreted-text role="gh"}.) - `$_asynctask` is added to access the current asyncio task if applicable. (Contributed by Tian Gao in `124367`{.interpreted-text role="gh"}.) - `pdb.set_trace_async`{.interpreted-text role="func"} is added to support debugging asyncio coroutines. `await`{.interpreted-text role="keyword"} statements are supported with this function. (Contributed by Tian Gao in `132576`{.interpreted-text role="gh"}.) - Source code displayed in `pdb`{.interpreted-text role="mod"} will be syntax-highlighted. This feature can be controlled using the same methods as the default `interactive`{.interpreted-text role="term"} shell, in addition to the newly added `colorize` argument of `pdb.Pdb`{.interpreted-text role="class"}. (Contributed by Tian Gao and Łukasz Langa in `133355`{.interpreted-text role="gh"}.) ### pickle - Set the default protocol version on the `pickle`{.interpreted-text role="mod"} module to 5. For more details, see `pickle protocols `{.interpreted-text role="ref"}. - Add exception notes for pickle serialization errors that allow identifying the source of the error. (Contributed by Serhiy Storchaka in `122213`{.interpreted-text role="gh"}.) ### platform - Add `~platform.invalidate_caches`{.interpreted-text role="func"}, a function to invalidate cached results in the `!platform`{.interpreted-text role="mod"} module. (Contributed by Bénédikt Tran in `122549`{.interpreted-text role="gh"}.) ### pydoc - `Annotations `{.interpreted-text role="term"} in help output are now usually displayed in a format closer to that in the original source. (Contributed by Jelle Zijlstra in `101552`{.interpreted-text role="gh"}.) ### re - Support `\z` as a synonym for `\Z` in `regular expressions `{.interpreted-text role="mod"}. It is interpreted unambiguously in many other regular expression engines, unlike `\Z`, which has subtly different behavior. (Contributed by Serhiy Storchaka in `133306`{.interpreted-text role="gh"}.) - `\B` in `regular expression `{.interpreted-text role="mod"} now matches the empty input string, meaning that it is now always the opposite of `\b`. (Contributed by Serhiy Storchaka in `124130`{.interpreted-text role="gh"}.) ### socket - Improve and fix support for Bluetooth sockets. - Fix support of Bluetooth sockets on NetBSD and DragonFly BSD. (Contributed by Serhiy Storchaka in `132429`{.interpreted-text role="gh"}.) - Fix support for `~socket.BTPROTO_HCI`{.interpreted-text role="const"} on FreeBSD. (Contributed by Victor Stinner in `111178`{.interpreted-text role="gh"}.) - Add support for `~socket.BTPROTO_SCO`{.interpreted-text role="const"} on FreeBSD. (Contributed by Serhiy Storchaka in `85302`{.interpreted-text role="gh"}.) - Add support for *cid* and *bdaddr_type* in the address for `~socket.BTPROTO_L2CAP`{.interpreted-text role="const"} on FreeBSD. (Contributed by Serhiy Storchaka in `132429`{.interpreted-text role="gh"}.) - Add support for *channel* in the address for `~socket.BTPROTO_HCI`{.interpreted-text role="const"} on Linux. (Contributed by Serhiy Storchaka in `70145`{.interpreted-text role="gh"}.) - Accept an integer as the address for `~socket.BTPROTO_HCI`{.interpreted-text role="const"} on Linux. (Contributed by Serhiy Storchaka in `132099`{.interpreted-text role="gh"}.) - Return *cid* in `~socket.socket.getsockname`{.interpreted-text role="meth"} for `~socket.BTPROTO_L2CAP`{.interpreted-text role="const"}. (Contributed by Serhiy Storchaka in `132429`{.interpreted-text role="gh"}.) - Add many new constants. (Contributed by Serhiy Storchaka in `132734`{.interpreted-text role="gh"}.) ### ssl - Indicate through the `~ssl.HAS_PHA`{.interpreted-text role="data"} Boolean whether the `!ssl`{.interpreted-text role="mod"} module supports TLSv1.3 post-handshake client authentication (PHA). (Contributed by Will Childs-Klein in `128036`{.interpreted-text role="gh"}.) ### struct - Support the `float complex`{.interpreted-text role="c:expr"} and `double complex`{.interpreted-text role="c:expr"} C types in the `struct`{.interpreted-text role="mod"} module (formatting characters `'F'` and `'D'` respectively). (Contributed by Sergey B Kirpichev in `121249`{.interpreted-text role="gh"}.) ### symtable - Expose the following `~symtable.Symbol`{.interpreted-text role="class"} methods: - `~symtable.Symbol.is_comp_cell`{.interpreted-text role="meth"} - `~symtable.Symbol.is_comp_iter`{.interpreted-text role="meth"} - `~symtable.Symbol.is_free_class`{.interpreted-text role="meth"} (Contributed by Bénédikt Tran in `120029`{.interpreted-text role="gh"}.) ### sys - The previously undocumented special function `sys.getobjects`{.interpreted-text role="func"}, which only exists in specialized builds of Python, may now return objects from other interpreters than the one it\'s called in. (Contributed by Eric Snow in `125286`{.interpreted-text role="gh"}.) - Add `sys._is_immortal`{.interpreted-text role="func"} for determining if an object is `immortal`{.interpreted-text role="term"}. (Contributed by Peter Bierma in `128509`{.interpreted-text role="gh"}.) - On FreeBSD, `sys.platform`{.interpreted-text role="data"} no longer contains the major version number. It is always `'freebsd'`, instead of `'freebsd13'` or `'freebsd14'`. (Contributed by Michael Osipov in `129393`{.interpreted-text role="gh"}.) - Raise `DeprecationWarning`{.interpreted-text role="exc"} for `sys._clear_type_cache`{.interpreted-text role="func"}. This function was deprecated in Python 3.13 but it didn\'t raise a runtime warning. - Add `sys.remote_exec`{.interpreted-text role="func"} to implement the new external debugger interface. See `PEP 768 `{.interpreted-text role="ref"} for details. (Contributed by Pablo Galindo Salgado, Matt Wozniski, and Ivona Stojanovic in `131591`{.interpreted-text role="gh"}.) - Add the `sys._jit`{.interpreted-text role="data"} namespace, containing utilities for introspecting just-in-time compilation. (Contributed by Brandt Bucher in `133231`{.interpreted-text role="gh"}.) ### sys.monitoring - Add two new monitoring events, `BRANCH_LEFT`{.interpreted-text role="monitoring-event"} and `BRANCH_RIGHT`{.interpreted-text role="monitoring-event"}. These replace and deprecate the `!BRANCH`{.interpreted-text role="monitoring-event"} event. (Contributed by Mark Shannon in `122548`{.interpreted-text role="gh"}.) ### sysconfig - Add `ABIFLAGS` key to `~sysconfig.get_config_vars`{.interpreted-text role="func"} on Windows. (Contributed by Xuehai Pan in `131799`{.interpreted-text role="gh"}.) ### tarfile - `~tarfile.data_filter`{.interpreted-text role="func"} now normalizes symbolic link targets in order to avoid path traversal attacks. (Contributed by Petr Viktorin in `127987`{.interpreted-text role="gh"} and `2025-4138`{.interpreted-text role="cve"}.) - `~tarfile.TarFile.extractall`{.interpreted-text role="func"} now skips fixing up directory attributes when a directory was removed or replaced by another kind of file. (Contributed by Petr Viktorin in `127987`{.interpreted-text role="gh"} and `2024-12718`{.interpreted-text role="cve"}.) - `~tarfile.TarFile.extract`{.interpreted-text role="func"} and `~tarfile.TarFile.extractall`{.interpreted-text role="func"} now (re-)apply the extraction filter when substituting a link (hard or symbolic) with a copy of another archive member, and when fixing up directory attributes. The former raises a new exception, `~tarfile.LinkFallbackError`{.interpreted-text role="exc"}. (Contributed by Petr Viktorin for `2025-4330`{.interpreted-text role="cve"} and `2024-12718`{.interpreted-text role="cve"}.) - `~tarfile.TarFile.extract`{.interpreted-text role="func"} and `~tarfile.TarFile.extractall`{.interpreted-text role="func"} no longer extract rejected members when `~tarfile.TarFile.errorlevel`{.interpreted-text role="func"} is zero. (Contributed by Matt Prodani and Petr Viktorin in `112887`{.interpreted-text role="gh"} and `2025-4435`{.interpreted-text role="cve"}.) ### threading - `threading.Thread.start`{.interpreted-text role="meth"} now sets the operating system thread name to `threading.Thread.name`{.interpreted-text role="attr"}. (Contributed by Victor Stinner in `59705`{.interpreted-text role="gh"}.) ### tkinter - Make `tkinter`{.interpreted-text role="mod"} widget methods `!after`{.interpreted-text role="meth"} and `!after_idle`{.interpreted-text role="meth"} accept keyword arguments. (Contributed by Zhikang Yan in `126899`{.interpreted-text role="gh"}.) - Add ability to specify a name for `!tkinter.OptionMenu`{.interpreted-text role="class"} and `!tkinter.ttk.OptionMenu`{.interpreted-text role="class"}. (Contributed by Zhikang Yan in `130482`{.interpreted-text role="gh"}.) ### turtle - Add context managers for `turtle.fill`{.interpreted-text role="func"}, `turtle.poly`{.interpreted-text role="func"}, and `turtle.no_animation`{.interpreted-text role="func"}. (Contributed by Marie Roald and Yngve Mardal Moe in `126350`{.interpreted-text role="gh"}.) ### types - `types.UnionType`{.interpreted-text role="class"} is now an alias for `typing.Union`{.interpreted-text role="class"}. See `below `{.interpreted-text role="ref"} for more details. (Contributed by Jelle Zijlstra in `105499`{.interpreted-text role="gh"}.) ### typing ::: {#whatsnew314-typing-union} - The `types.UnionType`{.interpreted-text role="class"} and `typing.Union`{.interpreted-text role="class"} types are now aliases for each other, meaning that both old-style unions (created with `Union[int, str]`) and new-style unions (`int | str`) now create instances of the same runtime type. This unifies the behavior between the two syntaxes, but leads to some differences in behavior that may affect users who introspect types at runtime: - Both syntaxes for creating a union now produce the same string representation in `repr`{.interpreted-text role="func"}. For example, `repr(Union[int, str])` is now `"int | str"` instead of `"typing.Union[int, str]"`. - Unions created using the old syntax are no longer cached. Previously, running `Union[int, str]` multiple times would return the same object (`Union[int, str] is Union[int, str]` would be `True`), but now it will return two different objects. Use `==` to compare unions for equality, not `is`. New-style unions have never been cached this way. This change could increase memory usage for some programs that use a large number of unions created by subscripting `typing.Union`. However, several factors offset this cost: unions used in annotations are no longer evaluated by default in Python 3.14 because of `649`{.interpreted-text role="pep"}; an instance of `types.UnionType`{.interpreted-text role="class"} is itself much smaller than the object returned by `Union[]` was on prior Python versions; and removing the cache also saves some space. It is therefore unlikely that this change will cause a significant increase in memory usage for most users. - Previously, old-style unions were implemented using the private class `typing._UnionGenericAlias`. This class is no longer needed for the implementation, but it has been retained for backward compatibility, with removal scheduled for Python 3.17. Users should use documented introspection helpers like `~typing.get_origin`{.interpreted-text role="func"} and `typing.get_args`{.interpreted-text role="func"} instead of relying on private implementation details. - It is now possible to use `typing.Union`{.interpreted-text role="class"} itself in `isinstance`{.interpreted-text role="func"} checks. For example, `isinstance(int | str, typing.Union)` will return `True`; previously this raised `TypeError`{.interpreted-text role="exc"}. - The `!__args__`{.interpreted-text role="attr"} attribute of `typing.Union`{.interpreted-text role="class"} objects is no longer writable. - It is no longer possible to set any attributes on `~typing.Union`{.interpreted-text role="class"} objects. This only ever worked for dunder attributes on previous versions, was never documented to work, and was subtly broken in many cases. (Contributed by Jelle Zijlstra in `105499`{.interpreted-text role="gh"}.) - `~typing.TypeAliasType`{.interpreted-text role="class"} now supports star unpacking. ::: ### unicodedata - The Unicode database has been updated to Unicode 16.0.0. ### unittest ::: {#whatsnew314-color-unittest} - `unittest`{.interpreted-text role="mod"} output is now colored by default. This can be controlled by `environment variables `{.interpreted-text role="ref"}. (Contributed by Hugo van Kemenade in `127221`{.interpreted-text role="gh"}.) - unittest discovery supports `namespace package`{.interpreted-text role="term"} as start directory again. It was removed in Python 3.11. (Contributed by Jacob Walls in `80958`{.interpreted-text role="gh"}.) - A number of new methods were added in the `~unittest.TestCase`{.interpreted-text role="class"} class that provide more specialized tests. - `~unittest.TestCase.assertHasAttr`{.interpreted-text role="meth"} and `~unittest.TestCase.assertNotHasAttr`{.interpreted-text role="meth"} check whether the object has a particular attribute. - `~unittest.TestCase.assertIsSubclass`{.interpreted-text role="meth"} and `~unittest.TestCase.assertNotIsSubclass`{.interpreted-text role="meth"} check whether the object is a subclass of a particular class, or of one of a tuple of classes. - `~unittest.TestCase.assertStartsWith`{.interpreted-text role="meth"}, `~unittest.TestCase.assertNotStartsWith`{.interpreted-text role="meth"}, `~unittest.TestCase.assertEndsWith`{.interpreted-text role="meth"} and `~unittest.TestCase.assertNotEndsWith`{.interpreted-text role="meth"} check whether the Unicode or byte string starts or ends with particular strings. (Contributed by Serhiy Storchaka in `71339`{.interpreted-text role="gh"}.) ::: ### urllib - Upgrade HTTP digest authentication algorithm for `urllib.request`{.interpreted-text role="mod"} by supporting SHA-256 digest authentication as specified in `7616`{.interpreted-text role="rfc"}. (Contributed by Calvin Bui in `128193`{.interpreted-text role="gh"}.) - Improve ergonomics and standards compliance when parsing and emitting `file:` URLs. In `~urllib.request.url2pathname`{.interpreted-text role="func"}: - Accept a complete URL when the new *require_scheme* argument is set to true. - Discard URL authority if it matches the local hostname. - Discard URL authority if it resolves to a local IP address when the new *resolve_host* argument is set to true. - Discard URL query and fragment components. - Raise `~urllib.error.URLError`{.interpreted-text role="exc"} if a URL authority isn\'t local, except on Windows where we return a UNC path as before. In `~urllib.request.pathname2url`{.interpreted-text role="func"}: - Return a complete URL when the new *add_scheme* argument is set to true. - Include an empty URL authority when a path begins with a slash. For example, the path `/etc/hosts` is converted to the URL `///etc/hosts`. On Windows, drive letters are no longer converted to uppercase, and `:` characters not following a drive letter no longer cause an `OSError`{.interpreted-text role="exc"} exception to be raised. (Contributed by Barney Gale in `125866`{.interpreted-text role="gh"}.) ### uuid - Add support for UUID versions 6, 7, and 8 via `~uuid.uuid6`{.interpreted-text role="func"}, `~uuid.uuid7`{.interpreted-text role="func"}, and `~uuid.uuid8`{.interpreted-text role="func"} respectively, as specified in `9562`{.interpreted-text role="rfc"}. (Contributed by Bénédikt Tran in `89083`{.interpreted-text role="gh"}.) - `~uuid.NIL`{.interpreted-text role="const"} and `~uuid.MAX`{.interpreted-text role="const"} are now available to represent the Nil and Max UUID formats as defined by `9562`{.interpreted-text role="rfc"}. (Contributed by Nick Pope in `128427`{.interpreted-text role="gh"}.) - Allow generating multiple UUIDs simultaneously on the command-line via `python -m uuid --count `{.interpreted-text role="option"}. (Contributed by Simon Legner in `131236`{.interpreted-text role="gh"}.) ### webbrowser - Names in the `BROWSER`{.interpreted-text role="envvar"} environment variable can now refer to already registered browsers for the `webbrowser`{.interpreted-text role="mod"} module, instead of always generating a new browser command. This makes it possible to set `BROWSER`{.interpreted-text role="envvar"} to the value of one of the supported browsers on macOS. ### zipfile - Added `ZipInfo._for_archive `{.interpreted-text role="meth"}, a method to resolve suitable defaults for a `~zipfile.ZipInfo`{.interpreted-text role="class"} object as used by `ZipFile.writestr `{.interpreted-text role="func"}. (Contributed by Bénédikt Tran in `123424`{.interpreted-text role="gh"}.) - `.ZipFile.writestr`{.interpreted-text role="meth"} now respects the `SOURCE_DATE_EPOCH`{.interpreted-text role="envvar"} environment variable in order to better support reproducible builds. (Contributed by Jiahao Li in `91279`{.interpreted-text role="gh"}.) ## Optimizations - The import time for several standard library modules has been improved, including `annotationlib`{.interpreted-text role="mod"}, `ast`{.interpreted-text role="mod"}, `asyncio`{.interpreted-text role="mod"}, `base64`{.interpreted-text role="mod"}, `cmd`{.interpreted-text role="mod"}, `csv`{.interpreted-text role="mod"}, `gettext`{.interpreted-text role="mod"}, `importlib.util`{.interpreted-text role="mod"}, `locale`{.interpreted-text role="mod"}, `mimetypes`{.interpreted-text role="mod"}, `optparse`{.interpreted-text role="mod"}, `pickle`{.interpreted-text role="mod"}, `pprint`{.interpreted-text role="mod"}, `pstats`{.interpreted-text role="mod"}, `shlex`{.interpreted-text role="mod"}, `socket`{.interpreted-text role="mod"}, `string`{.interpreted-text role="mod"}, `subprocess`{.interpreted-text role="mod"}, `threading`{.interpreted-text role="mod"}, `tomllib`{.interpreted-text role="mod"}, `types`{.interpreted-text role="mod"}, and `zipfile`{.interpreted-text role="mod"}. (Contributed by Adam Turner, Bénédikt Tran, Chris Markiewicz, Eli Schwartz, Hugo van Kemenade, Jelle Zijlstra, and others in `118761`{.interpreted-text role="gh"}.) - The interpreter now avoids some reference count modifications internally when it\'s safe to do so. This can lead to different values being returned from `sys.getrefcount`{.interpreted-text role="func"} and `Py_REFCNT`{.interpreted-text role="c:func"} compared to previous versions of Python. See `below `{.interpreted-text role="ref"} for details. ### asyncio - Standard benchmark results have improved by 10-20% following the implementation of a new per-thread doubly linked list for `native tasks `{.interpreted-text role="class"}, also reducing memory usage. This enables external introspection tools such as `python -m asyncio pstree `{.interpreted-text role="ref"} to introspect the call graph of asyncio tasks running in all threads. (Contributed by Kumar Aditya in `107803`{.interpreted-text role="gh"}.) - The module now has first class support for `free-threading builds `{.interpreted-text role="term"}. This enables parallel execution of multiple event loops across different threads, scaling linearly with the number of threads. (Contributed by Kumar Aditya in `128002`{.interpreted-text role="gh"}.) ### base64 - `~base64.b16decode`{.interpreted-text role="func"} is now up to six times faster. (Contributed by Bénédikt Tran, Chris Markiewicz, and Adam Turner in `118761`{.interpreted-text role="gh"}.) ### bdb - The basic debugger now has a `sys.monitoring`{.interpreted-text role="mod"}-based backend, which can be selected via the passing `'monitoring'` to the `~bdb.Bdb`{.interpreted-text role="class"} class\'s new *backend* parameter. (Contributed by Tian Gao in `124533`{.interpreted-text role="gh"}.) ### difflib - The `~difflib.IS_LINE_JUNK`{.interpreted-text role="func"} function is now up to twice as fast. (Contributed by Adam Turner and Semyon Moroz in `130167`{.interpreted-text role="gh"}.) ### gc - The new `incremental garbage collector `{.interpreted-text role="ref"} means that maximum pause times are reduced by an order of magnitude or more for larger heaps. Because of this optimization, the meaning of the results of `~gc.get_threshold`{.interpreted-text role="meth"} and `~gc.set_threshold`{.interpreted-text role="meth"} have changed, along with `~gc.get_count`{.interpreted-text role="meth"} and `~gc.get_stats`{.interpreted-text role="meth"}. - For backwards compatibility, `~gc.get_threshold`{.interpreted-text role="meth"} continues to return a three-item tuple. The first value is the threshold for young collections, as before; the second value determines the rate at which the old collection is scanned (the default is 10, and higher values mean that the old collection is scanned more slowly). The third value is now meaningless and is always zero. - `~gc.set_threshold`{.interpreted-text role="meth"} now ignores any items after the second. - `~gc.get_count`{.interpreted-text role="meth"} and `~gc.get_stats`{.interpreted-text role="meth"} continue to return the same format of results. The only difference is that instead of the results referring to the young, aging and old generations, the results refer to the young generation and the aging and collecting spaces of the old generation. In summary, code that attempted to manipulate the behavior of the cycle GC may not work exactly as intended, but it is very unlikely to be harmful. All other code will work just fine. (Contributed by Mark Shannon in `108362`{.interpreted-text role="gh"}.) ### io - Opening and reading files now executes fewer system calls. Reading a small operating system cached file in full is up to 15% faster. (Contributed by Cody Maloney and Victor Stinner in `120754`{.interpreted-text role="gh"} and `90102`{.interpreted-text role="gh"}.) ### pathlib - `Path.read_bytes `{.interpreted-text role="func"} now uses unbuffered mode to open files, which is between 9% and 17% faster to read in full. (Contributed by Cody Maloney in `120754`{.interpreted-text role="gh"}.) ### pdb - `pdb`{.interpreted-text role="mod"} now supports two backends, based on either `sys.settrace`{.interpreted-text role="func"} or `sys.monitoring`{.interpreted-text role="mod"}. Using the `pdb CLI `{.interpreted-text role="ref"} or `breakpoint`{.interpreted-text role="func"} will always use the `sys.monitoring`{.interpreted-text role="mod"} backend. Explicitly instantiating `pdb.Pdb`{.interpreted-text role="class"} and its derived classes will use the `sys.settrace`{.interpreted-text role="func"} backend by default, which is configurable. (Contributed by Tian Gao in `124533`{.interpreted-text role="gh"}.) ### textwrap - Optimize the `~textwrap.dedent`{.interpreted-text role="func"} function, improving performance by an average of 2.4x, with larger improvements for bigger inputs, and fix a bug with incomplete normalization of blank lines with whitespace characters other than space and tab. ### uuid - `~uuid.uuid3`{.interpreted-text role="func"} and `~uuid.uuid5`{.interpreted-text role="func"} are now both roughly 40% faster for 16-byte names and 20% faster for 1024-byte names. Performance for longer names remains unchanged. (Contributed by Bénédikt Tran in `128150`{.interpreted-text role="gh"}.) - `~uuid.uuid4`{.interpreted-text role="func"} is now c. 30% faster. (Contributed by Bénédikt Tran in `128150`{.interpreted-text role="gh"}.) ### zlib - On Windows, [zlib-ng](https://github.com/zlib-ng/zlib-ng) is now used as the implementation of the `zlib`{.interpreted-text role="mod"} module in the default binaries. There are no known incompatibilities between `zlib-ng` and the previously-used `zlib` implementation. This should result in better performance at all compression levels. It is worth noting that `zlib.Z_BEST_SPEED` (`1`) may result in significantly less compression than the previous implementation, whilst also significantly reducing the time taken to compress. (Contributed by Steve Dower in `91349`{.interpreted-text role="gh"}.) ## Removed ### argparse - Remove the *type*, *choices*, and *metavar* parameters of `!BooleanOptionalAction`{.interpreted-text role="class"}. These have been deprecated since Python 3.12. (Contributed by Nikita Sobolev in `118805`{.interpreted-text role="gh"}.) - Calling `~argparse.ArgumentParser.add_argument_group`{.interpreted-text role="meth"} on an argument group now raises a `ValueError`{.interpreted-text role="exc"}. Similarly, `~argparse.ArgumentParser.add_argument_group`{.interpreted-text role="meth"} or `~argparse.ArgumentParser.add_mutually_exclusive_group`{.interpreted-text role="meth"} on a mutually exclusive group now both raise `ValueError`{.interpreted-text role="exc"}s. This \'nesting\' was never supported, often failed to work correctly, and was unintentionally exposed through inheritance. This functionality has been deprecated since Python 3.11. (Contributed by Savannah Ostrowski in `127186`{.interpreted-text role="gh"}.) ### ast - Remove the following classes, which have been deprecated aliases of `~ast.Constant`{.interpreted-text role="class"} since Python 3.8 and have emitted deprecation warnings since Python 3.12: - `!Bytes`{.interpreted-text role="class"} - `!Ellipsis`{.interpreted-text role="class"} - `!NameConstant`{.interpreted-text role="class"} - `!Num`{.interpreted-text role="class"} - `!Str`{.interpreted-text role="class"} As a consequence of these removals, user-defined `visit_Num`, `visit_Str`, `visit_Bytes`, `visit_NameConstant` and `visit_Ellipsis` methods on custom `~ast.NodeVisitor`{.interpreted-text role="class"} subclasses will no longer be called when the `!NodeVisitor`{.interpreted-text role="class"} subclass is visiting an AST. Define a `visit_Constant` method instead. (Contributed by Alex Waygood in `119562`{.interpreted-text role="gh"}.) - Remove the following deprecated properties on `ast.Constant`{.interpreted-text role="class"}, which were present for compatibility with the now-removed AST classes: - `!Constant.n`{.interpreted-text role="attr"} - `!Constant.s`{.interpreted-text role="attr"} Use `!Constant.value`{.interpreted-text role="attr"} instead. (Contributed by Alex Waygood in `119562`{.interpreted-text role="gh"}.) ### asyncio - Remove the following classes, methods, and functions, which have been deprecated since Python 3.12: - `!AbstractChildWatcher`{.interpreted-text role="class"} - `!FastChildWatcher`{.interpreted-text role="class"} - `!MultiLoopChildWatcher`{.interpreted-text role="class"} - `!PidfdChildWatcher`{.interpreted-text role="class"} - `!SafeChildWatcher`{.interpreted-text role="class"} - `!ThreadedChildWatcher`{.interpreted-text role="class"} - `!AbstractEventLoopPolicy.get_child_watcher`{.interpreted-text role="meth"} - `!AbstractEventLoopPolicy.set_child_watcher`{.interpreted-text role="meth"} - `!get_child_watcher`{.interpreted-text role="func"} - `!set_child_watcher`{.interpreted-text role="func"} (Contributed by Kumar Aditya in `120804`{.interpreted-text role="gh"}.) - `asyncio.get_event_loop`{.interpreted-text role="func"} now raises a `RuntimeError`{.interpreted-text role="exc"} if there is no current event loop, and no longer implicitly creates an event loop. (Contributed by Kumar Aditya in `126353`{.interpreted-text role="gh"}.) There\'s a few patterns that use `asyncio.get_event_loop`{.interpreted-text role="func"}, most of them can be replaced with `asyncio.run`{.interpreted-text role="func"}. If you\'re running an async function, simply use `asyncio.run`{.interpreted-text role="func"}. Before: ``` python async def main(): ... loop = asyncio.get_event_loop() try: loop.run_until_complete(main()) finally: loop.close() ``` After: ``` python async def main(): ... asyncio.run(main()) ``` If you need to start something, for example, a server listening on a socket and then run forever, use `asyncio.run`{.interpreted-text role="func"} and an `asyncio.Event`{.interpreted-text role="class"}. Before: ``` python def start_server(loop): ... loop = asyncio.get_event_loop() try: start_server(loop) loop.run_forever() finally: loop.close() ``` After: ``` python def start_server(loop): ... async def main(): start_server(asyncio.get_running_loop()) await asyncio.Event().wait() asyncio.run(main()) ``` If you need to run something in an event loop, then run some blocking code around it, use `asyncio.Runner`{.interpreted-text role="class"}. Before: ``` python async def operation_one(): ... def blocking_code(): ... async def operation_two(): ... loop = asyncio.get_event_loop() try: loop.run_until_complete(operation_one()) blocking_code() loop.run_until_complete(operation_two()) finally: loop.close() ``` After: ``` python async def operation_one(): ... def blocking_code(): ... async def operation_two(): ... with asyncio.Runner() as runner: runner.run(operation_one()) blocking_code() runner.run(operation_two()) ``` ### email - Remove `email.utils.localtime`{.interpreted-text role="func"}\'s *isdst* parameter, which was deprecated in and has been ignored since Python 3.12. (Contributed by Hugo van Kemenade in `118798`{.interpreted-text role="gh"}.) ### importlib.abc - Remove deprecated `importlib.abc`{.interpreted-text role="mod"} classes: - `!ResourceReader`{.interpreted-text role="class"} (use `~importlib.resources.abc.TraversableResources`{.interpreted-text role="class"}) - `!Traversable`{.interpreted-text role="class"} (use `~importlib.resources.abc.Traversable`{.interpreted-text role="class"}) - `!TraversableResources`{.interpreted-text role="class"} (use `~importlib.resources.abc.TraversableResources`{.interpreted-text role="class"}) (Contributed by Jason R. Coombs and Hugo van Kemenade in `93963`{.interpreted-text role="gh"}.) ### itertools - Remove support for copy, deepcopy, and pickle operations from `itertools`{.interpreted-text role="mod"} iterators. These have emitted a `DeprecationWarning`{.interpreted-text role="exc"} since Python 3.12. (Contributed by Raymond Hettinger in `101588`{.interpreted-text role="gh"}.) ### pathlib - Remove support for passing additional keyword arguments to `~pathlib.Path`{.interpreted-text role="class"}. In previous versions, any such arguments are ignored. (Contributed by Barney Gale in `74033`{.interpreted-text role="gh"}.) - Remove support for passing additional positional arguments to `.PurePath.relative_to`{.interpreted-text role="meth"} and `~pathlib.PurePath.is_relative_to`{.interpreted-text role="meth"}. In previous versions, any such arguments are joined onto *other*. (Contributed by Barney Gale in `78707`{.interpreted-text role="gh"}.) ### pkgutil - Remove the `!get_loader`{.interpreted-text role="func"} and `!find_loader`{.interpreted-text role="func"} functions, which have been deprecated since Python 3.12. (Contributed by Bénédikt Tran in `97850`{.interpreted-text role="gh"}.) ### pty - Remove the `!master_open`{.interpreted-text role="func"} and `!slave_open`{.interpreted-text role="func"} functions, which have been deprecated since Python 3.12. Use `pty.openpty`{.interpreted-text role="func"} instead. (Contributed by Nikita Sobolev in `118824`{.interpreted-text role="gh"}.) ### sqlite3 - Remove `!version`{.interpreted-text role="data"} and `!version_info`{.interpreted-text role="data"} from the `sqlite3`{.interpreted-text role="mod"} module; use `~sqlite3.sqlite_version`{.interpreted-text role="data"} and `~sqlite3.sqlite_version_info`{.interpreted-text role="data"} for the actual version number of the runtime SQLite library. (Contributed by Hugo van Kemenade in `118924`{.interpreted-text role="gh"}.) - Using a sequence of parameters with named placeholders now raises a `~sqlite3.ProgrammingError`{.interpreted-text role="exc"}, having been deprecated since Python 3.12. (Contributed by Erlend E. Aasland in `118928`{.interpreted-text role="gh"} and `101693`{.interpreted-text role="gh"}.) ### urllib - Remove the `!Quoter`{.interpreted-text role="class"} class from `urllib.parse`{.interpreted-text role="mod"}, which has been deprecated since Python 3.11. (Contributed by Nikita Sobolev in `118827`{.interpreted-text role="gh"}.) - Remove the `!URLopener`{.interpreted-text role="class"} and `!FancyURLopener`{.interpreted-text role="class"} classes from `urllib.request`{.interpreted-text role="mod"}, which have been deprecated since Python 3.3. `myopener.open()` can be replaced with `~urllib.request.urlopen`{.interpreted-text role="func"}. `myopener.retrieve()` can be replaced with `~urllib.request.urlretrieve`{.interpreted-text role="func"}. Customisations to the opener classes can be replaced by passing customized handlers to `~urllib.request.build_opener`{.interpreted-text role="func"}. (Contributed by Barney Gale in `84850`{.interpreted-text role="gh"}.) ## Deprecated ### New deprecations - Passing a complex number as the *real* or *imag* argument in the `complex`{.interpreted-text role="func"} constructor is now deprecated; complex numbers should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in `109218`{.interpreted-text role="gh"}.) - `argparse`{.interpreted-text role="mod"}: - Passing the undocumented keyword argument *prefix_chars* to the `~argparse.ArgumentParser.add_argument_group`{.interpreted-text role="meth"} method is now deprecated. (Contributed by Savannah Ostrowski in `125563`{.interpreted-text role="gh"}.) - Deprecated the `argparse.FileType`{.interpreted-text role="class"} type converter. Anything relating to resource management should be handled downstream, after the arguments have been parsed. (Contributed by Serhiy Storchaka in `58032`{.interpreted-text role="gh"}.) - `asyncio`{.interpreted-text role="mod"}: - The `!asyncio.iscoroutinefunction`{.interpreted-text role="func"} is now deprecated and will be removed in Python 3.16; use `inspect.iscoroutinefunction`{.interpreted-text role="func"} instead. (Contributed by Jiahao Li and Kumar Aditya in `122875`{.interpreted-text role="gh"}.) - The `asyncio`{.interpreted-text role="mod"} policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated: - `asyncio.AbstractEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.DefaultEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.WindowsSelectorEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.WindowsProactorEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.get_event_loop_policy`{.interpreted-text role="func"} - `asyncio.set_event_loop_policy`{.interpreted-text role="func"} Users should use `asyncio.run`{.interpreted-text role="func"} or `asyncio.Runner`{.interpreted-text role="class"} with the *loop_factory* argument to use the desired event loop implementation. For example, to use `asyncio.SelectorEventLoop`{.interpreted-text role="class"} on Windows: ``` python import asyncio async def main(): ... asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop) ``` (Contributed by Kumar Aditya in `127949`{.interpreted-text role="gh"}.) - `codecs`{.interpreted-text role="mod"}: The `codecs.open`{.interpreted-text role="func"} function is now deprecated, and will be removed in a future version of Python. Use `open`{.interpreted-text role="func"} instead. (Contributed by Inada Naoki in `133036`{.interpreted-text role="gh"}.) - `ctypes`{.interpreted-text role="mod"}: - On non-Windows platforms, setting `.Structure._pack_`{.interpreted-text role="attr"} to use a MSVC-compatible default memory layout is now deprecated in favor of setting `.Structure._layout_`{.interpreted-text role="attr"} to `'ms'`, and will be removed in Python 3.19. (Contributed by Petr Viktorin in `131747`{.interpreted-text role="gh"}.) - Calling `ctypes.POINTER`{.interpreted-text role="func"} on a string is now deprecated. Use `incomplete types `{.interpreted-text role="ref"} for self-referential structures. Also, the internal `ctypes._pointer_type_cache` is deprecated. See `ctypes.POINTER`{.interpreted-text role="func"} for updated implementation details. (Contributed by Sergey Myrianov in `100926`{.interpreted-text role="gh"}.) - `functools`{.interpreted-text role="mod"}: Calling the Python implementation of `functools.reduce`{.interpreted-text role="func"} with *function* or *sequence* as keyword arguments is now deprecated; the parameters will be made positional-only in Python 3.16. (Contributed by Kirill Podoprigora in `121676`{.interpreted-text role="gh"}.) - `logging`{.interpreted-text role="mod"}: Support for custom logging handlers with the *strm* argument is now deprecated and scheduled for removal in Python 3.16. Define handlers with the *stream* argument instead. (Contributed by Mariusz Felisiak in `115032`{.interpreted-text role="gh"}.) - `mimetypes`{.interpreted-text role="mod"}: Valid extensions are either empty or must start with \'.\' for `mimetypes.MimeTypes.add_type`{.interpreted-text role="meth"}. Undotted extensions are deprecated and will raise a `ValueError`{.interpreted-text role="exc"} in Python 3.16. (Contributed by Hugo van Kemenade in `75223`{.interpreted-text role="gh"}.) - `!nturl2path`{.interpreted-text role="mod"}: This module is now deprecated. Call `urllib.request.url2pathname`{.interpreted-text role="func"} and `~urllib.request.pathname2url`{.interpreted-text role="func"} instead. (Contributed by Barney Gale in `125866`{.interpreted-text role="gh"}.) - `os`{.interpreted-text role="mod"}: The `os.popen`{.interpreted-text role="func"} and `os.spawn* `{.interpreted-text role="func"} functions are now `soft deprecated`{.interpreted-text role="term"}. They should no longer be used to write new code. The `subprocess`{.interpreted-text role="mod"} module is recommended instead. (Contributed by Victor Stinner in `120743`{.interpreted-text role="gh"}.) - `pathlib`{.interpreted-text role="mod"}: `!pathlib.PurePath.as_uri`{.interpreted-text role="meth"} is now deprecated and scheduled for removal in Python 3.19. Use `pathlib.Path.as_uri`{.interpreted-text role="meth"} instead. (Contributed by Barney Gale in `123599`{.interpreted-text role="gh"}.) - `pdb`{.interpreted-text role="mod"}: The undocumented `pdb.Pdb.curframe_locals` attribute is now a deprecated read-only property, which will be removed in a future version of Python. The low overhead dynamic frame locals access added in Python 3.13 by `667`{.interpreted-text role="pep"} means the frame locals cache reference previously stored in this attribute is no longer needed. Derived debuggers should access `pdb.Pdb.curframe.f_locals` directly in Python 3.13 and later versions. (Contributed by Tian Gao in `124369`{.interpreted-text role="gh"} and `125951`{.interpreted-text role="gh"}.) - `symtable`{.interpreted-text role="mod"}: Deprecate `symtable.Class.get_methods`{.interpreted-text role="meth"} due to the lack of interest, scheduled for removal in Python 3.16. (Contributed by Bénédikt Tran in `119698`{.interpreted-text role="gh"}.) - `tkinter`{.interpreted-text role="mod"}: The `!tkinter.Variable`{.interpreted-text role="class"} methods `!trace_variable`{.interpreted-text role="meth"}, `!trace_vdelete`{.interpreted-text role="meth"} and `!trace_vinfo`{.interpreted-text role="meth"} are now deprecated. Use `!trace_add`{.interpreted-text role="meth"}, `!trace_remove`{.interpreted-text role="meth"} and `!trace_info`{.interpreted-text role="meth"} instead. (Contributed by Serhiy Storchaka in `120220`{.interpreted-text role="gh"}.) - `urllib.parse`{.interpreted-text role="mod"}: Accepting objects with false values (like `0` and `[]`) except empty strings, bytes-like objects and `None` in `~urllib.parse.parse_qsl`{.interpreted-text role="func"} and `~urllib.parse.parse_qs`{.interpreted-text role="func"} is now deprecated. (Contributed by Serhiy Storchaka in `116897`{.interpreted-text role="gh"}.) ### Pending removal in Python 3.15 - The import system: - Setting `__cached__` on a module while failing to set `__spec__.cached `{.interpreted-text role="attr"} is deprecated. In Python 3.15, `__cached__` will cease to be set or take into consideration by the import system or standard library. (`97879`{.interpreted-text role="gh"}) - Setting `~module.__package__`{.interpreted-text role="attr"} on a module while failing to set `__spec__.parent `{.interpreted-text role="attr"} is deprecated. In Python 3.15, `!__package__`{.interpreted-text role="attr"} will cease to be set or take into consideration by the import system or standard library. (`97879`{.interpreted-text role="gh"}) - `ctypes`{.interpreted-text role="mod"}: - The undocumented `!ctypes.SetPointerType`{.interpreted-text role="func"} function has been deprecated since Python 3.13. - `http.server`{.interpreted-text role="mod"}: - The obsolete and rarely used `!CGIHTTPRequestHandler`{.interpreted-text role="class"} 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`{.interpreted-text role="option"} flag to the `python -m http.server`{.interpreted-text role="program"} command-line interface has been deprecated since Python 3.13. - `importlib`{.interpreted-text role="mod"}: - `load_module()` method: use `exec_module()` instead. - `pathlib`{.interpreted-text role="mod"}: - `!.PurePath.is_reserved`{.interpreted-text role="meth"} has been deprecated since Python 3.13. Use `os.path.isreserved`{.interpreted-text role="func"} to detect reserved paths on Windows. - `platform`{.interpreted-text role="mod"}: - `!platform.java_ver`{.interpreted-text role="func"} has been deprecated since Python 3.13. This function is only useful for Jython support, has a confusing API, and is largely untested. - `sysconfig`{.interpreted-text role="mod"}: - The *check_home* argument of `sysconfig.is_python_build`{.interpreted-text role="func"} has been deprecated since Python 3.12. - `threading`{.interpreted-text role="mod"}: - `~threading.RLock`{.interpreted-text role="func"} 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`{.interpreted-text role="mod"}: - `types.CodeType`{.interpreted-text role="class"}: Accessing `~codeobject.co_lnotab`{.interpreted-text role="attr"} was deprecated in `626`{.interpreted-text role="pep"} since 3.10 and was planned to be removed in 3.12, but it only got a proper `DeprecationWarning`{.interpreted-text role="exc"} in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in `101866`{.interpreted-text role="gh"}.) - `typing`{.interpreted-text role="mod"}: - The undocumented keyword argument syntax for creating `~typing.NamedTuple`{.interpreted-text role="class"} classes (for example, `Point = NamedTuple("Point", x=int, y=int)`) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead. - When using the functional syntax of `~typing.TypedDict`{.interpreted-text role="class"}s, failing to pass a value to the *fields* parameter (`TD = TypedDict("TD")`) or passing `None` (`TD = TypedDict("TD", None)`) has been deprecated since Python 3.13. Use `class TD(TypedDict): pass` or `TD = TypedDict("TD", {})` to create a TypedDict with zero field. - The `!typing.no_type_check_decorator`{.interpreted-text role="func"} decorator function has been deprecated since Python 3.13. After eight years in the `typing`{.interpreted-text role="mod"} module, it has yet to be supported by any major type checker. - `!sre_compile`{.interpreted-text role="mod"}, `!sre_constants`{.interpreted-text role="mod"} and `!sre_parse`{.interpreted-text role="mod"} modules. - `wave`{.interpreted-text role="mod"}: - The `getmark()`, `setmark()` and `getmarkers()` methods of the `~wave.Wave_read`{.interpreted-text role="class"} and `~wave.Wave_write`{.interpreted-text role="class"} classes have been deprecated since Python 3.13. - `zipimport`{.interpreted-text role="mod"}: - `!zipimport.zipimporter.load_module`{.interpreted-text role="meth"} has been deprecated since Python 3.10. Use `~zipimport.zipimporter.exec_module`{.interpreted-text role="meth"} instead. (`125746`{.interpreted-text role="gh"}.) ### Pending removal in Python 3.16 - The import system: - Setting `~module.__loader__`{.interpreted-text role="attr"} on a module while failing to set `__spec__.loader `{.interpreted-text role="attr"} is deprecated. In Python 3.16, `!__loader__`{.interpreted-text role="attr"} will cease to be set or taken into consideration by the import system or the standard library. - `array`{.interpreted-text role="mod"}: - The `'u'` format code (`wchar_t`{.interpreted-text role="c:type"}) has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use the `'w'` format code (`Py_UCS4`{.interpreted-text role="c:type"}) for Unicode characters instead. - `asyncio`{.interpreted-text role="mod"}: - `!asyncio.iscoroutinefunction`{.interpreted-text role="func"} is deprecated and will be removed in Python 3.16; use `inspect.iscoroutinefunction`{.interpreted-text role="func"} instead. (Contributed by Jiahao Li and Kumar Aditya in `122875`{.interpreted-text role="gh"}.) - `asyncio`{.interpreted-text role="mod"} policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated: - `asyncio.AbstractEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.DefaultEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.WindowsSelectorEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.WindowsProactorEventLoopPolicy`{.interpreted-text role="class"} - `asyncio.get_event_loop_policy`{.interpreted-text role="func"} - `asyncio.set_event_loop_policy`{.interpreted-text role="func"} Users should use `asyncio.run`{.interpreted-text role="func"} or `asyncio.Runner`{.interpreted-text role="class"} with *loop_factory* to use the desired event loop implementation. For example, to use `asyncio.SelectorEventLoop`{.interpreted-text role="class"} on Windows: import asyncio async def main(): ... asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop) (Contributed by Kumar Aditya in `127949`{.interpreted-text role="gh"}.) - `builtins`{.interpreted-text role="mod"}: - Bitwise inversion on boolean types, `~True` or `~False` has been deprecated since Python 3.12, as it produces surprising and unintuitive results (`-2` and `-1`). Use `not x` instead for the logical negation of a Boolean. In the rare case that you need the bitwise inversion of the underlying integer, convert to `int` explicitly (`~int(x)`). - `functools`{.interpreted-text role="mod"}: - Calling the Python implementation of `functools.reduce`{.interpreted-text role="func"} with *function* or *sequence* as keyword arguments has been deprecated since Python 3.14. - `logging`{.interpreted-text role="mod"}: - Support for custom logging handlers with the *strm* argument is deprecated and scheduled for removal in Python 3.16. Define handlers with the *stream* argument instead. (Contributed by Mariusz Felisiak in `115032`{.interpreted-text role="gh"}.) - `mimetypes`{.interpreted-text role="mod"}: - Valid extensions start with a \'.\' or are empty for `mimetypes.MimeTypes.add_type`{.interpreted-text role="meth"}. Undotted extensions are deprecated and will raise a `ValueError`{.interpreted-text role="exc"} in Python 3.16. (Contributed by Hugo van Kemenade in `75223`{.interpreted-text role="gh"}.) - `shutil`{.interpreted-text role="mod"}: - The `!ExecError`{.interpreted-text role="class"} exception has been deprecated since Python 3.14. It has not been used by any function in `!shutil`{.interpreted-text role="mod"} since Python 3.4, and is now an alias of `RuntimeError`{.interpreted-text role="exc"}. - `symtable`{.interpreted-text role="mod"}: - The `Class.get_methods `{.interpreted-text role="meth"} method has been deprecated since Python 3.14. - `sys`{.interpreted-text role="mod"}: - The `~sys._enablelegacywindowsfsencoding`{.interpreted-text role="func"} function has been deprecated since Python 3.13. Use the `PYTHONLEGACYWINDOWSFSENCODING`{.interpreted-text role="envvar"} environment variable instead. - `sysconfig`{.interpreted-text role="mod"}: - The `!sysconfig.expand_makefile_vars`{.interpreted-text role="func"} function has been deprecated since Python 3.14. Use the `vars` argument of `sysconfig.get_paths`{.interpreted-text role="func"} instead. - `tarfile`{.interpreted-text role="mod"}: - The undocumented and unused `!TarFile.tarfile`{.interpreted-text role="attr"} attribute has been deprecated since Python 3.13. ### Pending removal in Python 3.17 - `collections.abc`{.interpreted-text role="mod"}: - `collections.abc.ByteString`{.interpreted-text role="class"} is scheduled for removal in Python 3.17. Use `isinstance(obj, collections.abc.Buffer)` to test if `obj` implements the `buffer protocol `{.interpreted-text role="ref"} at runtime. For use in type annotations, either use `~collections.abc.Buffer`{.interpreted-text role="class"} or a union that explicitly specifies the types your code supports (e.g., `bytes | bytearray | memoryview`). `!ByteString`{.interpreted-text role="class"} was originally intended to be an abstract class that would serve as a supertype of both `bytes`{.interpreted-text role="class"} and `bytearray`{.interpreted-text role="class"}. However, since the ABC never had any methods, knowing that an object was an instance of `!ByteString`{.interpreted-text role="class"} never actually told you anything useful about the object. Other common buffer types such as `memoryview`{.interpreted-text role="class"} were also never understood as subtypes of `!ByteString`{.interpreted-text role="class"} (either at runtime or by static type checkers). See `PEP 688 <688#current-options>`{.interpreted-text role="pep"} for more details. (Contributed by Shantanu Jain in `91896`{.interpreted-text role="gh"}.) - `encodings`{.interpreted-text role="mod"}: - Passing non-ascii *encoding* names to `encodings.normalize_encoding`{.interpreted-text role="func"} is deprecated and scheduled for removal in Python 3.17. (Contributed by Stan Ulbrych in `136702`{.interpreted-text role="gh"}) - `typing`{.interpreted-text role="mod"}: - Before Python 3.14, old-style unions were implemented using the private class `typing._UnionGenericAlias`. This class is no longer needed for the implementation, but it has been retained for backward compatibility, with removal scheduled for Python 3.17. Users should use documented introspection helpers like `typing.get_origin`{.interpreted-text role="func"} and `typing.get_args`{.interpreted-text role="func"} instead of relying on private implementation details. - `typing.ByteString`{.interpreted-text role="class"}, deprecated since Python 3.9, is scheduled for removal in Python 3.17. Use `isinstance(obj, collections.abc.Buffer)` to test if `obj` implements the `buffer protocol `{.interpreted-text role="ref"} at runtime. For use in type annotations, either use `~collections.abc.Buffer`{.interpreted-text role="class"} or a union that explicitly specifies the types your code supports (e.g., `bytes | bytearray | memoryview`). `!ByteString`{.interpreted-text role="class"} was originally intended to be an abstract class that would serve as a supertype of both `bytes`{.interpreted-text role="class"} and `bytearray`{.interpreted-text role="class"}. However, since the ABC never had any methods, knowing that an object was an instance of `!ByteString`{.interpreted-text role="class"} never actually told you anything useful about the object. Other common buffer types such as `memoryview`{.interpreted-text role="class"} were also never understood as subtypes of `!ByteString`{.interpreted-text role="class"} (either at runtime or by static type checkers). See `PEP 688 <688#current-options>`{.interpreted-text role="pep"} for more details. (Contributed by Shantanu Jain in `91896`{.interpreted-text role="gh"}.) ### Pending removal in Python 3.18 - `decimal`{.interpreted-text role="mod"}: - The non-standard and undocumented `~decimal.Decimal`{.interpreted-text role="class"} format specifier `'N'`, which is only supported in the `!decimal`{.interpreted-text role="mod"} module\'s C implementation, has been deprecated since Python 3.13. (Contributed by Serhiy Storchaka in `89902`{.interpreted-text role="gh"}.) ### Pending removal in Python 3.19 - `ctypes`{.interpreted-text role="mod"}: - Implicitly switching to the MSVC-compatible struct layout by setting `~ctypes.Structure._pack_`{.interpreted-text role="attr"} but not `~ctypes.Structure._layout_`{.interpreted-text role="attr"} on non-Windows platforms. - `hashlib`{.interpreted-text role="mod"}: - In hash function constructors such as `~hashlib.new`{.interpreted-text role="func"} or the direct hash-named constructors such as `~hashlib.md5`{.interpreted-text role="func"} and `~hashlib.sha256`{.interpreted-text role="func"}, their optional initial data parameter could also be passed a keyword argument named `data=` or `string=` in various `!hashlib`{.interpreted-text role="mod"} implementations. Support for the `string` keyword argument name is now deprecated and slated for removal in Python 3.19. Before Python 3.13, the `string` keyword parameter was not correctly supported depending on the backend implementation of hash functions. Prefer passing the initial data as a positional argument for maximum backwards compatibility. ### Pending removal in Python 3.20 - The `__version__`, `version` and `VERSION` attributes have been deprecated in these standard library modules and will be removed in Python 3.20. Use `sys.version_info`{.interpreted-text role="py:data"} instead. - `argparse`{.interpreted-text role="mod"} - `csv`{.interpreted-text role="mod"} - `ctypes`{.interpreted-text role="mod"} - `!ctypes.macholib`{.interpreted-text role="mod"} - `decimal`{.interpreted-text role="mod"} (use `decimal.SPEC_VERSION`{.interpreted-text role="data"} instead) - `http.server`{.interpreted-text role="mod"} - `imaplib`{.interpreted-text role="mod"} - `ipaddress`{.interpreted-text role="mod"} - `json`{.interpreted-text role="mod"} - `logging`{.interpreted-text role="mod"} (`__date__` also deprecated) - `optparse`{.interpreted-text role="mod"} - `pickle`{.interpreted-text role="mod"} - `platform`{.interpreted-text role="mod"} - `re`{.interpreted-text role="mod"} - `socketserver`{.interpreted-text role="mod"} - `tabnanny`{.interpreted-text role="mod"} - `tkinter.font`{.interpreted-text role="mod"} - `tkinter.ttk`{.interpreted-text role="mod"} - `wsgiref.simple_server`{.interpreted-text role="mod"} - `xml.etree.ElementTree`{.interpreted-text role="mod"} - `!xml.sax.expatreader`{.interpreted-text role="mod"} - `xml.sax.handler`{.interpreted-text role="mod"} - `zlib`{.interpreted-text role="mod"} (Contributed by Hugo van Kemenade and Stan Ulbrych in `76007`{.interpreted-text role="gh"}.) ### 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`{.interpreted-text role="mod"}: - Nesting argument groups and nesting mutually exclusive groups are deprecated. - Passing the undocumented keyword argument *prefix_chars* to `~argparse.ArgumentParser.add_argument_group`{.interpreted-text role="meth"} is now deprecated. - The `argparse.FileType`{.interpreted-text role="class"} type converter is deprecated. - `builtins`{.interpreted-text role="mod"}: - Generators: `throw(type, exc, tb)` and `athrow(type, exc, tb)` signature is deprecated: use `throw(exc)` and `athrow(exc)` instead, the single argument signature. - Currently Python accepts numeric literals immediately followed by keywords, for example `0in x`, `1or x`, `0if 1else 2`. It allows confusing and ambiguous expressions like `[0x1for x in y]` (which can be interpreted as `[0x1 for x in y]` or `[0x1f or x in y]`). A syntax warning is raised if the numeric literal is immediately followed by one of keywords `and`{.interpreted-text role="keyword"}, `else`{.interpreted-text role="keyword"}, `for`{.interpreted-text role="keyword"}, `if`{.interpreted-text role="keyword"}, `in`{.interpreted-text role="keyword"}, `is`{.interpreted-text role="keyword"} and `or`{.interpreted-text role="keyword"}. In a future release it will be changed to a syntax error. (`87999`{.interpreted-text role="gh"}) - Support for `__index__()` and `__int__()` method returning non-int type: these methods will be required to return an instance of a strict subclass of `int`{.interpreted-text role="class"}. - Support for `__float__()` method returning a strict subclass of `float`{.interpreted-text role="class"}: these methods will be required to return an instance of `float`{.interpreted-text role="class"}. - Support for `__complex__()` method returning a strict subclass of `complex`{.interpreted-text role="class"}: these methods will be required to return an instance of `complex`{.interpreted-text role="class"}. - Passing a complex number as the *real* or *imag* argument in the `complex`{.interpreted-text role="func"} constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in `109218`{.interpreted-text role="gh"}.) - `calendar`{.interpreted-text role="mod"}: `calendar.January` and `calendar.February` constants are deprecated and replaced by `calendar.JANUARY`{.interpreted-text role="data"} and `calendar.FEBRUARY`{.interpreted-text role="data"}. (Contributed by Prince Roshan in `103636`{.interpreted-text role="gh"}.) - `codecs`{.interpreted-text role="mod"}: use `open`{.interpreted-text role="func"} instead of `codecs.open`{.interpreted-text role="func"}. (`133038`{.interpreted-text role="gh"}) - `codeobject.co_lnotab`{.interpreted-text role="attr"}: use the `codeobject.co_lines`{.interpreted-text role="meth"} method instead. - `datetime`{.interpreted-text role="mod"}: - `~datetime.datetime.utcnow`{.interpreted-text role="meth"}: use `datetime.datetime.now(tz=datetime.UTC)`. - `~datetime.datetime.utcfromtimestamp`{.interpreted-text role="meth"}: use `datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC)`. - `gettext`{.interpreted-text role="mod"}: Plural value must be an integer. - `importlib`{.interpreted-text role="mod"}: - `~importlib.util.cache_from_source`{.interpreted-text role="func"} *debug_override* parameter is deprecated: use the *optimization* parameter instead. - `importlib.metadata`{.interpreted-text role="mod"}: - `EntryPoints` tuple interface. - Implicit `None` on return values. - `logging`{.interpreted-text role="mod"}: the `warn()` method has been deprecated since Python 3.3, use `~logging.warning`{.interpreted-text role="meth"} instead. - `mailbox`{.interpreted-text role="mod"}: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead. - `os`{.interpreted-text role="mod"}: Calling `os.register_at_fork`{.interpreted-text role="func"} in a multi-threaded process. - `os.path`{.interpreted-text role="mod"}: `os.path.commonprefix`{.interpreted-text role="func"} is deprecated, use `os.path.commonpath`{.interpreted-text role="func"} for path prefixes. The `os.path.commonprefix`{.interpreted-text role="func"} function is being deprecated due to having a misleading name and module. The function is not safe to use for path prefixes despite being included in a module about path manipulation, meaning it is easy to accidentally introduce path traversal vulnerabilities into Python programs by using this function. - `!pydoc.ErrorDuringImport`{.interpreted-text role="class"}: A tuple value for *exc_info* parameter is deprecated, use an exception instance. - `re`{.interpreted-text role="mod"}: More strict rules are now applied for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore. (Contributed by Serhiy Storchaka in `91760`{.interpreted-text role="gh"}.) - `shutil`{.interpreted-text role="mod"}: `~shutil.rmtree`{.interpreted-text role="func"}\'s *onerror* parameter is deprecated in Python 3.12; use the *onexc* parameter instead. - `ssl`{.interpreted-text role="mod"} options and protocols: - `ssl.SSLContext`{.interpreted-text role="class"} without protocol argument is deprecated. - `ssl.SSLContext`{.interpreted-text role="class"}: `~ssl.SSLContext.set_npn_protocols`{.interpreted-text role="meth"} and `!selected_npn_protocol`{.interpreted-text role="meth"} are deprecated: use ALPN instead. - `ssl.OP_NO_SSL*` options - `ssl.OP_NO_TLS*` options - `ssl.PROTOCOL_SSLv3` - `ssl.PROTOCOL_TLS` - `ssl.PROTOCOL_TLSv1` - `ssl.PROTOCOL_TLSv1_1` - `ssl.PROTOCOL_TLSv1_2` - `ssl.TLSVersion.SSLv3` - `ssl.TLSVersion.TLSv1` - `ssl.TLSVersion.TLSv1_1` - `threading`{.interpreted-text role="mod"} methods: - `!threading.Condition.notifyAll`{.interpreted-text role="meth"}: use `~threading.Condition.notify_all`{.interpreted-text role="meth"}. - `!threading.Event.isSet`{.interpreted-text role="meth"}: use `~threading.Event.is_set`{.interpreted-text role="meth"}. - `!threading.Thread.isDaemon`{.interpreted-text role="meth"}, `threading.Thread.setDaemon`{.interpreted-text role="meth"}: use `threading.Thread.daemon`{.interpreted-text role="attr"} attribute. - `!threading.Thread.getName`{.interpreted-text role="meth"}, `threading.Thread.setName`{.interpreted-text role="meth"}: use `threading.Thread.name`{.interpreted-text role="attr"} attribute. - `!threading.currentThread`{.interpreted-text role="meth"}: use `threading.current_thread`{.interpreted-text role="meth"}. - `!threading.activeCount`{.interpreted-text role="meth"}: use `threading.active_count`{.interpreted-text role="meth"}. - `typing.Text`{.interpreted-text role="class"} (`92332`{.interpreted-text role="gh"}). - The internal class `typing._UnionGenericAlias` is no longer used to implement `typing.Union`{.interpreted-text role="class"}. To preserve compatibility with users using this private class, a compatibility shim will be provided until at least Python 3.17. (Contributed by Jelle Zijlstra in `105499`{.interpreted-text role="gh"}.) - `unittest.IsolatedAsyncioTestCase`{.interpreted-text role="class"}: it is deprecated to return a value that is not `None` from a test case. - `urllib.parse`{.interpreted-text role="mod"} deprecated functions: `~urllib.parse.urlparse`{.interpreted-text role="func"} instead - `splitattr()` - `splithost()` - `splitnport()` - `splitpasswd()` - `splitport()` - `splitquery()` - `splittag()` - `splittype()` - `splituser()` - `splitvalue()` - `to_bytes()` - `wsgiref`{.interpreted-text role="mod"}: `SimpleHandler.stdout.write()` should not do partial writes. - `xml.etree.ElementTree`{.interpreted-text role="mod"}: Testing the truth value of an `~xml.etree.ElementTree.Element`{.interpreted-text role="class"} is deprecated. In a future release it will always return `True`. Prefer explicit `len(elem)` or `elem is not None` tests instead. - `sys._clear_type_cache`{.interpreted-text role="func"} is deprecated: use `sys._clear_internal_caches`{.interpreted-text role="func"} instead. ## CPython bytecode changes - Replaced the opcode `!BINARY_SUBSCR`{.interpreted-text role="opcode"} by the `BINARY_OP`{.interpreted-text role="opcode"} opcode with the `NB_SUBSCR` oparg. (Contributed by Irit Katriel in `100239`{.interpreted-text role="gh"}.) - Add the `BUILD_INTERPOLATION`{.interpreted-text role="opcode"} and `BUILD_TEMPLATE`{.interpreted-text role="opcode"} opcodes to construct new `~string.templatelib.Interpolation`{.interpreted-text role="class"} and `~string.templatelib.Template`{.interpreted-text role="class"} instances, respectively. (Contributed by Lysandros Nikolaou and others in `132661`{.interpreted-text role="gh"}; see also `PEP 750: Template strings `{.interpreted-text role="ref"}). - Remove the `!BUILD_CONST_KEY_MAP`{.interpreted-text role="opcode"} opcode. Use `BUILD_MAP`{.interpreted-text role="opcode"} instead. (Contributed by Mark Shannon in `122160`{.interpreted-text role="gh"}.) - Replace the `!LOAD_ASSERTION_ERROR`{.interpreted-text role="opcode"} opcode with `LOAD_COMMON_CONSTANT`{.interpreted-text role="opcode"} and add support for loading `NotImplementedError`{.interpreted-text role="exc"}. - Add the `LOAD_FAST_BORROW`{.interpreted-text role="opcode"} and `LOAD_FAST_BORROW_LOAD_FAST_BORROW`{.interpreted-text role="opcode"} opcodes to reduce reference counting overhead when the interpreter can prove that the reference in the frame outlives the reference loaded onto the stack. (Contributed by Matt Page in `130704`{.interpreted-text role="gh"}.) - Add the `LOAD_SMALL_INT`{.interpreted-text role="opcode"} opcode, which pushes a small integer equal to the `oparg` to the stack. The `!RETURN_CONST`{.interpreted-text role="opcode"} opcode is removed as it is no longer used. (Contributed by Mark Shannon in `125837`{.interpreted-text role="gh"}.) - Add the new `LOAD_SPECIAL`{.interpreted-text role="opcode"} instruction. Generate code for `with`{.interpreted-text role="keyword"} and `async with`{.interpreted-text role="keyword"} statements using the new instruction. Removed the `!BEFORE_WITH`{.interpreted-text role="opcode"} and `!BEFORE_ASYNC_WITH`{.interpreted-text role="opcode"} instructions. (Contributed by Mark Shannon in `120507`{.interpreted-text role="gh"}.) - Add the `POP_ITER`{.interpreted-text role="opcode"} opcode to support \'virtual\' iterators. (Contributed by Mark Shannon in `132554`{.interpreted-text role="gh"}.) ### Pseudo-instructions - Add the `!ANNOTATIONS_PLACEHOLDER`{.interpreted-text role="opcode"} pseudo instruction to support partially executed module-level annotations with `deferred evaluation of annotations `{.interpreted-text role="ref"}. (Contributed by Jelle Zijlstra in `130907`{.interpreted-text role="gh"}.) - Add the `!BINARY_OP_EXTEND`{.interpreted-text role="opcode"} pseudo instruction, which executes a pair of functions (guard and specialization functions) accessed from the inline cache. (Contributed by Irit Katriel in `100239`{.interpreted-text role="gh"}.) - Add three specializations for `CALL_KW`{.interpreted-text role="opcode"}; `!CALL_KW_PY`{.interpreted-text role="opcode"} for calls to Python functions, `!CALL_KW_BOUND_METHOD`{.interpreted-text role="opcode"} for calls to bound methods, and `!CALL_KW_NON_PY`{.interpreted-text role="opcode"} for all other calls. (Contributed by Mark Shannon in `118093`{.interpreted-text role="gh"}.) - Add the `JUMP_IF_TRUE`{.interpreted-text role="opcode"} and `JUMP_IF_FALSE`{.interpreted-text role="opcode"} pseudo instructions, conditional jumps which do not impact the stack. Replaced by the sequence `COPY 1`, `TO_BOOL`, `POP_JUMP_IF_TRUE/FALSE`. (Contributed by Irit Katriel in `124285`{.interpreted-text role="gh"}.) - Add the `!LOAD_CONST_MORTAL`{.interpreted-text role="opcode"} pseudo instruction. (Contributed by Mark Shannon in `128685`{.interpreted-text role="gh"}.) - Add the `!LOAD_CONST_IMMORTAL`{.interpreted-text role="opcode"} pseudo instruction, which does the same as `!LOAD_CONST`{.interpreted-text role="opcode"}, but is more efficient for immortal objects. (Contributed by Mark Shannon in `125837`{.interpreted-text role="gh"}.) - Add the `NOT_TAKEN`{.interpreted-text role="opcode"} pseudo instruction, used by `sys.monitoring`{.interpreted-text role="mod"} to record branch events (such as `BRANCH_LEFT`{.interpreted-text role="monitoring-event"}). (Contributed by Mark Shannon in `122548`{.interpreted-text role="gh"}.) ## C API changes ### Python configuration C API {#whatsnew314-capi-config} Add a `PyInitConfig C API `{.interpreted-text role="ref"} to configure the Python initialization without relying on C structures and the ability to make ABI-compatible changes in the future. Complete the `587`{.interpreted-text role="pep"} `PyConfig C API `{.interpreted-text role="ref"} by adding `PyInitConfig_AddModule`{.interpreted-text role="c:func"} which can be used to add a built-in extension module; a feature previously referred to as the \"inittab\". Add `PyConfig_Get`{.interpreted-text role="c:func"} and `PyConfig_Set`{.interpreted-text role="c:func"} functions to get and set the current runtime configuration. `587`{.interpreted-text role="pep"} \'Python Initialization Configuration\' unified all the ways to configure Python\'s initialization. This PEP also unifies the configuration of Python\'s preinitialization and initialization in a single API. Moreover, this PEP only provides a single choice to embed Python, instead of having two \'Python\' and \'Isolated\' choices (PEP 587), to further simplify the API. The lower level PEP 587 PyConfig API remains available for use cases with an intentionally higher level of coupling to CPython implementation details (such as emulating the full functionality of CPython\'s CLI, including its configuration mechanisms). (Contributed by Victor Stinner in `107954`{.interpreted-text role="gh"}.) ::: seealso `741`{.interpreted-text role="pep"} and `587`{.interpreted-text role="pep"} ::: ### New features in the C API - Add `Py_PACK_VERSION`{.interpreted-text role="c:func"} and `Py_PACK_FULL_VERSION`{.interpreted-text role="c:func"}, two new macros for bit-packing Python version numbers. This is useful for comparisons with `Py_Version`{.interpreted-text role="c:var"} or `PY_VERSION_HEX`{.interpreted-text role="c:macro"}. (Contributed by Petr Viktorin in `128629`{.interpreted-text role="gh"}.) - Add `PyBytes_Join(sep, iterable) `{.interpreted-text role="c:func"} function, similar to `sep.join(iterable)` in Python. (Contributed by Victor Stinner in `121645`{.interpreted-text role="gh"}.) - Add functions to manipulate the configuration of the current runtime Python interpreter (`PEP 741: Python configuration C API `{.interpreted-text role="ref"}): - `PyConfig_Get`{.interpreted-text role="c:func"} - `PyConfig_GetInt`{.interpreted-text role="c:func"} - `PyConfig_Set`{.interpreted-text role="c:func"} - `PyConfig_Names`{.interpreted-text role="c:func"} (Contributed by Victor Stinner in `107954`{.interpreted-text role="gh"}.) - Add functions to configure Python initialization (`PEP 741: Python configuration C API `{.interpreted-text role="ref"}): - `Py_InitializeFromInitConfig`{.interpreted-text role="c:func"} - `PyInitConfig_AddModule`{.interpreted-text role="c:func"} - `PyInitConfig_Create`{.interpreted-text role="c:func"} - `PyInitConfig_Free`{.interpreted-text role="c:func"} - `PyInitConfig_FreeStrList`{.interpreted-text role="c:func"} - `PyInitConfig_GetError`{.interpreted-text role="c:func"} - `PyInitConfig_GetExitCode`{.interpreted-text role="c:func"} - `PyInitConfig_GetInt`{.interpreted-text role="c:func"} - `PyInitConfig_GetStr`{.interpreted-text role="c:func"} - `PyInitConfig_GetStrList`{.interpreted-text role="c:func"} - `PyInitConfig_HasOption`{.interpreted-text role="c:func"} - `PyInitConfig_SetInt`{.interpreted-text role="c:func"} - `PyInitConfig_SetStr`{.interpreted-text role="c:func"} - `PyInitConfig_SetStrList`{.interpreted-text role="c:func"} (Contributed by Victor Stinner in `107954`{.interpreted-text role="gh"}.) - Add `Py_fopen`{.interpreted-text role="c:func"} function to open a file. This works similarly to the standard C `!fopen`{.interpreted-text role="c:func"} function, instead accepting a Python object for the *path* parameter and setting an exception on error. The corresponding new `Py_fclose`{.interpreted-text role="c:func"} function should be used to close a file. (Contributed by Victor Stinner in `127350`{.interpreted-text role="gh"}.) - Add `Py_HashBuffer`{.interpreted-text role="c:func"} to compute and return the hash value of a buffer. (Contributed by Antoine Pitrou and Victor Stinner in `122854`{.interpreted-text role="gh"}.) - Add `PyImport_ImportModuleAttr`{.interpreted-text role="c:func"} and `PyImport_ImportModuleAttrString`{.interpreted-text role="c:func"} helper functions to import a module and get an attribute of the module. (Contributed by Victor Stinner in `128911`{.interpreted-text role="gh"}.) - Add `PyIter_NextItem`{.interpreted-text role="c:func"} to replace `PyIter_Next`{.interpreted-text role="c:func"}, which has an ambiguous return value. (Contributed by Irit Katriel and Erlend Aasland in `105201`{.interpreted-text role="gh"}.) - Add `PyLong_GetSign`{.interpreted-text role="c:func"} function to get the sign of `int`{.interpreted-text role="class"} objects. (Contributed by Sergey B Kirpichev in `116560`{.interpreted-text role="gh"}.) - Add `PyLong_IsPositive`{.interpreted-text role="c:func"}, `PyLong_IsNegative`{.interpreted-text role="c:func"} and `PyLong_IsZero`{.interpreted-text role="c:func"} for checking if `PyLongObject`{.interpreted-text role="c:type"} is positive, negative, or zero, respectively. (Contributed by James Roy and Sergey B Kirpichev in `126061`{.interpreted-text role="gh"}.) - Add new functions to convert C `` numbers to/from Python `int`{.interpreted-text role="class"} objects: - `PyLong_AsInt32`{.interpreted-text role="c:func"} - `PyLong_AsInt64`{.interpreted-text role="c:func"} - `PyLong_AsUInt32`{.interpreted-text role="c:func"} - `PyLong_AsUInt64`{.interpreted-text role="c:func"} - `PyLong_FromInt32`{.interpreted-text role="c:func"} - `PyLong_FromInt64`{.interpreted-text role="c:func"} - `PyLong_FromUInt32`{.interpreted-text role="c:func"} - `PyLong_FromUInt64`{.interpreted-text role="c:func"} (Contributed by Victor Stinner in `120389`{.interpreted-text role="gh"}.) - Add a new import and export API for Python `int`{.interpreted-text role="class"} objects (`757`{.interpreted-text role="pep"}): - `PyLong_GetNativeLayout`{.interpreted-text role="c:func"} - `PyLong_Export`{.interpreted-text role="c:func"} - `PyLong_FreeExport`{.interpreted-text role="c:func"} - `PyLongWriter_Create`{.interpreted-text role="c:func"} - `PyLongWriter_Finish`{.interpreted-text role="c:func"} - `PyLongWriter_Discard`{.interpreted-text role="c:func"} (Contributed by Sergey B Kirpichev and Victor Stinner in `102471`{.interpreted-text role="gh"}.) - Add `PyMonitoring_FireBranchLeftEvent`{.interpreted-text role="c:func"} and `PyMonitoring_FireBranchRightEvent`{.interpreted-text role="c:func"} for generating `BRANCH_LEFT`{.interpreted-text role="monitoring-event"} and `BRANCH_RIGHT`{.interpreted-text role="monitoring-event"} events, respectively. (Contributed by Mark Shannon in `122548`{.interpreted-text role="gh"}.) - Add `PyType_Freeze`{.interpreted-text role="c:func"} function to make a type immutable. (Contributed by Victor Stinner in `121654`{.interpreted-text role="gh"}.) - Add `PyType_GetBaseByToken`{.interpreted-text role="c:func"} and `Py_tp_token`{.interpreted-text role="c:data"} slot for easier superclass identification, which attempts to resolve the type checking issue mentioned in `PEP 630 <630#type-checking>`{.interpreted-text role="pep"}. (Contributed in `124153`{.interpreted-text role="gh"}.) - Add a new `PyUnicode_Equal`{.interpreted-text role="c:func"} function to test if two strings are equal. The function is also added to the Limited C API. (Contributed by Victor Stinner in `124502`{.interpreted-text role="gh"}.) - Add a new `PyUnicodeWriter`{.interpreted-text role="c:type"} API to create a Python `str`{.interpreted-text role="class"} object, with the following functions: - `PyUnicodeWriter_Create`{.interpreted-text role="c:func"} - `PyUnicodeWriter_DecodeUTF8Stateful`{.interpreted-text role="c:func"} - `PyUnicodeWriter_Discard`{.interpreted-text role="c:func"} - `PyUnicodeWriter_Finish`{.interpreted-text role="c:func"} - `PyUnicodeWriter_Format`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteASCII`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteChar`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteRepr`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteStr`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteSubstring`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteUCS4`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteUTF8`{.interpreted-text role="c:func"} - `PyUnicodeWriter_WriteWideChar`{.interpreted-text role="c:func"} (Contributed by Victor Stinner in `119182`{.interpreted-text role="gh"}.) - The `k` and `K` formats in `PyArg_ParseTuple`{.interpreted-text role="c:func"} and similar functions now use `~object.__index__`{.interpreted-text role="meth"} if available, like all other integer formats. (Contributed by Serhiy Storchaka in `112068`{.interpreted-text role="gh"}.) - Add support for a new `p` format unit in `Py_BuildValue`{.interpreted-text role="c:func"} that produces a Python `bool`{.interpreted-text role="class"} object from a C integer. (Contributed by Pablo Galindo in `45325`{.interpreted-text role="issue"}.) - Add `PyUnstable_IsImmortal`{.interpreted-text role="c:func"} for determining if an object is `immortal`{.interpreted-text role="term"}, for debugging purposes. (Contributed by Peter Bierma in `128509`{.interpreted-text role="gh"}.) - Add `PyUnstable_Object_EnableDeferredRefcount`{.interpreted-text role="c:func"} for enabling deferred reference counting, as outlined in `703`{.interpreted-text role="pep"}. - Add `PyUnstable_Object_IsUniquelyReferenced`{.interpreted-text role="c:func"} as a replacement for `Py_REFCNT(op) == 1` on `free threaded `{.interpreted-text role="term"} builds. (Contributed by Peter Bierma in `133140`{.interpreted-text role="gh"}.) - Add `PyUnstable_Object_IsUniqueReferencedTemporary`{.interpreted-text role="c:func"} to determine if an object is a unique temporary object on the interpreter\'s operand stack. This can be used in some cases as a replacement for checking if `Py_REFCNT`{.interpreted-text role="c:func"} is `1` for Python objects passed as arguments to C API functions. (Contributed by Sam Gross in `133164`{.interpreted-text role="gh"}.) ### Limited C API changes - In the limited C API version 3.14 and newer, `Py_TYPE`{.interpreted-text role="c:func"} and `Py_REFCNT`{.interpreted-text role="c:func"} are now implemented as an opaque function call to hide implementation details. (Contributed by Victor Stinner in `120600`{.interpreted-text role="gh"} and `124127`{.interpreted-text role="gh"}.) - Remove the `PySequence_Fast_GET_SIZE`{.interpreted-text role="c:macro"}, `PySequence_Fast_GET_ITEM`{.interpreted-text role="c:macro"}, and `PySequence_Fast_ITEMS`{.interpreted-text role="c:macro"} macros from the limited C API, since they have always been broken in the limited C API. (Contributed by Victor Stinner in `91417`{.interpreted-text role="gh"}.) ### Removed C APIs {#whatsnew314-c-api-removed} - Creating `immutable types `{.interpreted-text role="c:data"} with mutable bases was deprecated in Python 3.12, and now raises a `TypeError`{.interpreted-text role="exc"}. (Contributed by Nikita Sobolev in `119775`{.interpreted-text role="gh"}.) - Remove `PyDictObject.ma_version_tag` member, which was deprecated in Python 3.12. Use the `PyDict_AddWatcher`{.interpreted-text role="c:func"} API instead. (Contributed by Sam Gross in `124296`{.interpreted-text role="gh"}.) - Remove the private `_Py_InitializeMain()` function. It was a `provisional API`{.interpreted-text role="term"} added to Python 3.8 by `587`{.interpreted-text role="pep"}. (Contributed by Victor Stinner in `129033`{.interpreted-text role="gh"}.) - Remove the undocumented APIs `!Py_C_RECURSION_LIMIT`{.interpreted-text role="c:macro"} and `!PyThreadState.c_recursion_remaining`{.interpreted-text role="c:member"}. These were added in 3.13 and have been removed without deprecation. Use `Py_EnterRecursiveCall`{.interpreted-text role="c:func"} to guard against runaway recursion in C code. (Removed by Petr Viktorin in `133079`{.interpreted-text role="gh"}, see also `130396`{.interpreted-text role="gh"}.) ### Deprecated C APIs {#whatsnew314-c-api-deprecated} - The `!Py_HUGE_VAL`{.interpreted-text role="c:macro"} macro is now `soft deprecated`{.interpreted-text role="term"}. Use `!INFINITY`{.interpreted-text role="c:macro"} instead. (Contributed by Sergey B Kirpichev in `120026`{.interpreted-text role="gh"}.) - The `!Py_IS_NAN`{.interpreted-text role="c:macro"}, `!Py_IS_INFINITY`{.interpreted-text role="c:macro"}, and `!Py_IS_FINITE`{.interpreted-text role="c:macro"} macros are now `soft deprecated`{.interpreted-text role="term"}. Use `!isnan`{.interpreted-text role="c:macro"}, `!isinf`{.interpreted-text role="c:macro"} and `!isfinite`{.interpreted-text role="c:macro"} instead, available from `math.h`{.interpreted-text role="file"} since C99. (Contributed by Sergey B Kirpichev in `119613`{.interpreted-text role="gh"}.) - Non-tuple sequences are now deprecated as argument for the `(items)` format unit in `PyArg_ParseTuple`{.interpreted-text role="c:func"} and other `argument parsing `{.interpreted-text role="ref"} functions if *items* contains format units which store a `borrowed buffer `{.interpreted-text role="ref"} or a `borrowed reference`{.interpreted-text role="term"}. (Contributed by Serhiy Storchaka in `50333`{.interpreted-text role="gh"}.) - The `_PyMonitoring_FireBranchEvent` function is now deprecated and should be replaced with calls to `PyMonitoring_FireBranchLeftEvent`{.interpreted-text role="c:func"} and `PyMonitoring_FireBranchRightEvent`{.interpreted-text role="c:func"}. - The previously undocumented function `PySequence_In`{.interpreted-text role="c:func"} is now `soft deprecated`{.interpreted-text role="term"}. Use `PySequence_Contains`{.interpreted-text role="c:func"} instead. (Contributed by Yuki Kobayashi in `127896`{.interpreted-text role="gh"}.) #### Pending removal in Python 3.15 - The `!PyImport_ImportModuleNoBlock`{.interpreted-text role="c:func"}: Use `PyImport_ImportModule`{.interpreted-text role="c:func"} instead. - `!PyWeakref_GetObject`{.interpreted-text role="c:func"} and `!PyWeakref_GET_OBJECT`{.interpreted-text role="c:func"}: Use `PyWeakref_GetRef`{.interpreted-text role="c:func"} instead. The [pythoncapi-compat project](https://github.com/python/pythoncapi-compat/) can be used to get `PyWeakref_GetRef`{.interpreted-text role="c:func"} on Python 3.12 and older. - `Py_UNICODE`{.interpreted-text role="c:type"} type and the `!Py_UNICODE_WIDE`{.interpreted-text role="c:macro"} macro: Use `wchar_t`{.interpreted-text role="c:type"} instead. - `!PyUnicode_AsDecodedObject`{.interpreted-text role="c:func"}: Use `PyCodec_Decode`{.interpreted-text role="c:func"} instead. - `!PyUnicode_AsDecodedUnicode`{.interpreted-text role="c:func"}: Use `PyCodec_Decode`{.interpreted-text role="c:func"} instead; Note that some codecs (for example, \"base64\") may return a type other than `str`{.interpreted-text role="class"}, such as `bytes`{.interpreted-text role="class"}. - `!PyUnicode_AsEncodedObject`{.interpreted-text role="c:func"}: Use `PyCodec_Encode`{.interpreted-text role="c:func"} instead. - `!PyUnicode_AsEncodedUnicode`{.interpreted-text role="c:func"}: Use `PyCodec_Encode`{.interpreted-text role="c:func"} instead; Note that some codecs (for example, \"base64\") may return a type other than `bytes`{.interpreted-text role="class"}, such as `str`{.interpreted-text role="class"}. - Python initialization functions, deprecated in Python 3.13: - `!Py_GetPath`{.interpreted-text role="c:func"}: Use `PyConfig_Get("module_search_paths") `{.interpreted-text role="c:func"} (`sys.path`{.interpreted-text role="data"}) instead. - `!Py_GetPrefix`{.interpreted-text role="c:func"}: Use `PyConfig_Get("base_prefix") `{.interpreted-text role="c:func"} (`sys.base_prefix`{.interpreted-text role="data"}) instead. Use `PyConfig_Get("prefix") `{.interpreted-text role="c:func"} (`sys.prefix`{.interpreted-text role="data"}) if `virtual environments `{.interpreted-text role="ref"} need to be handled. - `!Py_GetExecPrefix`{.interpreted-text role="c:func"}: Use `PyConfig_Get("base_exec_prefix") `{.interpreted-text role="c:func"} (`sys.base_exec_prefix`{.interpreted-text role="data"}) instead. Use `PyConfig_Get("exec_prefix") `{.interpreted-text role="c:func"} (`sys.exec_prefix`{.interpreted-text role="data"}) if `virtual environments `{.interpreted-text role="ref"} need to be handled. - `!Py_GetProgramFullPath`{.interpreted-text role="c:func"}: Use `PyConfig_Get("executable") `{.interpreted-text role="c:func"} (`sys.executable`{.interpreted-text role="data"}) instead. - `!Py_GetProgramName`{.interpreted-text role="c:func"}: Use `PyConfig_Get("executable") `{.interpreted-text role="c:func"} (`sys.executable`{.interpreted-text role="data"}) instead. - `!Py_GetPythonHome`{.interpreted-text role="c:func"}: Use `PyConfig_Get("home") `{.interpreted-text role="c:func"} or the `PYTHONHOME`{.interpreted-text role="envvar"} environment variable instead. The [pythoncapi-compat project](https://github.com/python/pythoncapi-compat/) can be used to get `PyConfig_Get`{.interpreted-text role="c:func"} on Python 3.13 and older. - Functions to configure Python\'s initialization, deprecated in Python 3.11: - `!PySys_SetArgvEx()`{.interpreted-text role="c:func"}: Set `PyConfig.argv`{.interpreted-text role="c:member"} instead. - `!PySys_SetArgv()`{.interpreted-text role="c:func"}: Set `PyConfig.argv`{.interpreted-text role="c:member"} instead. - `!Py_SetProgramName()`{.interpreted-text role="c:func"}: Set `PyConfig.program_name`{.interpreted-text role="c:member"} instead. - `!Py_SetPythonHome()`{.interpreted-text role="c:func"}: Set `PyConfig.home`{.interpreted-text role="c:member"} instead. - `!PySys_ResetWarnOptions`{.interpreted-text role="c:func"}: Clear `sys.warnoptions`{.interpreted-text role="data"} and `!warnings.filters`{.interpreted-text role="data"} instead. The `Py_InitializeFromConfig`{.interpreted-text role="c:func"} API should be used with `PyConfig`{.interpreted-text role="c:type"} instead. - Global configuration variables: - `Py_DebugFlag`{.interpreted-text role="c:var"}: Use `PyConfig.parser_debug`{.interpreted-text role="c:member"} or `PyConfig_Get("parser_debug") `{.interpreted-text role="c:func"} instead. - `Py_VerboseFlag`{.interpreted-text role="c:var"}: Use `PyConfig.verbose`{.interpreted-text role="c:member"} or `PyConfig_Get("verbose") `{.interpreted-text role="c:func"} instead. - `Py_QuietFlag`{.interpreted-text role="c:var"}: Use `PyConfig.quiet`{.interpreted-text role="c:member"} or `PyConfig_Get("quiet") `{.interpreted-text role="c:func"} instead. - `Py_InteractiveFlag`{.interpreted-text role="c:var"}: Use `PyConfig.interactive`{.interpreted-text role="c:member"} or `PyConfig_Get("interactive") `{.interpreted-text role="c:func"} instead. - `Py_InspectFlag`{.interpreted-text role="c:var"}: Use `PyConfig.inspect`{.interpreted-text role="c:member"} or `PyConfig_Get("inspect") `{.interpreted-text role="c:func"} instead. - `Py_OptimizeFlag`{.interpreted-text role="c:var"}: Use `PyConfig.optimization_level`{.interpreted-text role="c:member"} or `PyConfig_Get("optimization_level") `{.interpreted-text role="c:func"} instead. - `Py_NoSiteFlag`{.interpreted-text role="c:var"}: Use `PyConfig.site_import`{.interpreted-text role="c:member"} or `PyConfig_Get("site_import") `{.interpreted-text role="c:func"} instead. - `Py_BytesWarningFlag`{.interpreted-text role="c:var"}: Use `PyConfig.bytes_warning`{.interpreted-text role="c:member"} or `PyConfig_Get("bytes_warning") `{.interpreted-text role="c:func"} instead. - `Py_FrozenFlag`{.interpreted-text role="c:var"}: Use `PyConfig.pathconfig_warnings`{.interpreted-text role="c:member"} or `PyConfig_Get("pathconfig_warnings") `{.interpreted-text role="c:func"} instead. - `Py_IgnoreEnvironmentFlag`{.interpreted-text role="c:var"}: Use `PyConfig.use_environment`{.interpreted-text role="c:member"} or `PyConfig_Get("use_environment") `{.interpreted-text role="c:func"} instead. - `Py_DontWriteBytecodeFlag`{.interpreted-text role="c:var"}: Use `PyConfig.write_bytecode`{.interpreted-text role="c:member"} or `PyConfig_Get("write_bytecode") `{.interpreted-text role="c:func"} instead. - `Py_NoUserSiteDirectory`{.interpreted-text role="c:var"}: Use `PyConfig.user_site_directory`{.interpreted-text role="c:member"} or `PyConfig_Get("user_site_directory") `{.interpreted-text role="c:func"} instead. - `Py_UnbufferedStdioFlag`{.interpreted-text role="c:var"}: Use `PyConfig.buffered_stdio`{.interpreted-text role="c:member"} or `PyConfig_Get("buffered_stdio") `{.interpreted-text role="c:func"} instead. - `Py_HashRandomizationFlag`{.interpreted-text role="c:var"}: Use `PyConfig.use_hash_seed`{.interpreted-text role="c:member"} and `PyConfig.hash_seed`{.interpreted-text role="c:member"} or `PyConfig_Get("hash_seed") `{.interpreted-text role="c:func"} instead. - `Py_IsolatedFlag`{.interpreted-text role="c:var"}: Use `PyConfig.isolated`{.interpreted-text role="c:member"} or `PyConfig_Get("isolated") `{.interpreted-text role="c:func"} instead. - `Py_LegacyWindowsFSEncodingFlag`{.interpreted-text role="c:var"}: Use `PyPreConfig.legacy_windows_fs_encoding`{.interpreted-text role="c:member"} or `PyConfig_Get("legacy_windows_fs_encoding") `{.interpreted-text role="c:func"} instead. - `Py_LegacyWindowsStdioFlag`{.interpreted-text role="c:var"}: Use `PyConfig.legacy_windows_stdio`{.interpreted-text role="c:member"} or `PyConfig_Get("legacy_windows_stdio") `{.interpreted-text role="c:func"} instead. - `!Py_FileSystemDefaultEncoding`{.interpreted-text role="c:var"}, `!Py_HasFileSystemDefaultEncoding`{.interpreted-text role="c:var"}: Use `PyConfig.filesystem_encoding`{.interpreted-text role="c:member"} or `PyConfig_Get("filesystem_encoding") `{.interpreted-text role="c:func"} instead. - `!Py_FileSystemDefaultEncodeErrors`{.interpreted-text role="c:var"}: Use `PyConfig.filesystem_errors`{.interpreted-text role="c:member"} or `PyConfig_Get("filesystem_errors") `{.interpreted-text role="c:func"} instead. - `!Py_UTF8Mode`{.interpreted-text role="c:var"}: Use `PyPreConfig.utf8_mode`{.interpreted-text role="c:member"} or `PyConfig_Get("utf8_mode") `{.interpreted-text role="c:func"} instead. (see `Py_PreInitialize`{.interpreted-text role="c:func"}) The `Py_InitializeFromConfig`{.interpreted-text role="c:func"} API should be used with `PyConfig`{.interpreted-text role="c:type"} to set these options. Or `PyConfig_Get`{.interpreted-text role="c:func"} 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`{.interpreted-text role="c:func"}: use `PyBytes_Join`{.interpreted-text role="c:func"}. - `!_PyDict_GetItemStringWithError`{.interpreted-text role="c:func"}: use `PyDict_GetItemStringRef`{.interpreted-text role="c:func"}. - `!_PyDict_Pop()`{.interpreted-text role="c:func"}: use `PyDict_Pop`{.interpreted-text role="c:func"}. - `!_PyLong_Sign()`{.interpreted-text role="c:func"}: use `PyLong_GetSign`{.interpreted-text role="c:func"}. - `!_PyLong_FromDigits`{.interpreted-text role="c:func"} and `!_PyLong_New`{.interpreted-text role="c:func"}: use `PyLongWriter_Create`{.interpreted-text role="c:func"}. - `!_PyThreadState_UncheckedGet`{.interpreted-text role="c:func"}: use `PyThreadState_GetUnchecked`{.interpreted-text role="c:func"}. - `!_PyUnicode_AsString`{.interpreted-text role="c:func"}: use `PyUnicode_AsUTF8`{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_Init`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_Init(&writer)` with `writer = PyUnicodeWriter_Create(0) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_Finish`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_Finish(&writer)` with `PyUnicodeWriter_Finish(writer) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_Dealloc`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_Dealloc(&writer)` with `PyUnicodeWriter_Discard(writer) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_WriteChar`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_WriteChar(&writer, ch)` with `PyUnicodeWriter_WriteChar(writer, ch) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_WriteStr`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_WriteStr(&writer, str)` with `PyUnicodeWriter_WriteStr(writer, str) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_WriteSubstring`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_WriteSubstring(&writer, str, start, end)` with `PyUnicodeWriter_WriteSubstring(writer, str, start, end) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_WriteASCIIString`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_WriteASCIIString(&writer, str)` with `PyUnicodeWriter_WriteASCII(writer, str) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_WriteLatin1String`{.interpreted-text role="c:func"}: replace `_PyUnicodeWriter_WriteLatin1String(&writer, str)` with `PyUnicodeWriter_WriteUTF8(writer, str) `{.interpreted-text role="c:func"}. - `!_PyUnicodeWriter_Prepare`{.interpreted-text role="c:func"}: (no replacement). - `!_PyUnicodeWriter_PrepareKind`{.interpreted-text role="c:func"}: (no replacement). - `!_Py_HashPointer`{.interpreted-text role="c:func"}: use `Py_HashPointer`{.interpreted-text role="c:func"}. - `!_Py_fopen_obj`{.interpreted-text role="c:func"}: use `Py_fopen`{.interpreted-text role="c:func"}. The [pythoncapi-compat project](https://github.com/python/pythoncapi-compat/) can be used to get these new public functions on Python 3.13 and older. (Contributed by Victor Stinner in `128863`{.interpreted-text role="gh"}.) #### 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`{.interpreted-text role="c:macro"}: Unneeded since Python 3.8. - `PyErr_Fetch`{.interpreted-text role="c:func"}: Use `PyErr_GetRaisedException`{.interpreted-text role="c:func"} instead. - `PyErr_NormalizeException`{.interpreted-text role="c:func"}: Use `PyErr_GetRaisedException`{.interpreted-text role="c:func"} instead. - `PyErr_Restore`{.interpreted-text role="c:func"}: Use `PyErr_SetRaisedException`{.interpreted-text role="c:func"} instead. - `PyModule_GetFilename`{.interpreted-text role="c:func"}: Use `PyModule_GetFilenameObject`{.interpreted-text role="c:func"} instead. - `PyOS_AfterFork`{.interpreted-text role="c:func"}: Use `PyOS_AfterFork_Child`{.interpreted-text role="c:func"} instead. - `PySlice_GetIndicesEx`{.interpreted-text role="c:func"}: Use `PySlice_Unpack`{.interpreted-text role="c:func"} and `PySlice_AdjustIndices`{.interpreted-text role="c:func"} instead. - `PyUnicode_READY`{.interpreted-text role="c:func"}: Unneeded since Python 3.12 - `!PyErr_Display`{.interpreted-text role="c:func"}: Use `PyErr_DisplayException`{.interpreted-text role="c:func"} instead. - `!_PyErr_ChainExceptions`{.interpreted-text role="c:func"}: Use `!_PyErr_ChainExceptions1`{.interpreted-text role="c:func"} instead. - `!PyBytesObject.ob_shash`{.interpreted-text role="c:member"} member: call `PyObject_Hash`{.interpreted-text role="c:func"} instead. - Thread Local Storage (TLS) API: - `PyThread_create_key`{.interpreted-text role="c:func"}: Use `PyThread_tss_alloc`{.interpreted-text role="c:func"} instead. - `PyThread_delete_key`{.interpreted-text role="c:func"}: Use `PyThread_tss_free`{.interpreted-text role="c:func"} instead. - `PyThread_set_key_value`{.interpreted-text role="c:func"}: Use `PyThread_tss_set`{.interpreted-text role="c:func"} instead. - `PyThread_get_key_value`{.interpreted-text role="c:func"}: Use `PyThread_tss_get`{.interpreted-text role="c:func"} instead. - `PyThread_delete_key_value`{.interpreted-text role="c:func"}: Use `PyThread_tss_delete`{.interpreted-text role="c:func"} instead. - `PyThread_ReInitTLS`{.interpreted-text role="c:func"}: Unneeded since Python 3.7. ## Build changes {#whatsnew314-build-changes} - `776`{.interpreted-text role="pep"}: Emscripten is now an officially supported platform at `tier 3 <11#tier-3>`{.interpreted-text role="pep"}. As a part of this effort, more than 25 bugs in [Emscripten libc](https://emscripten.org/docs/porting/emscripten-runtime-environment.html) were fixed. Emscripten now includes support for `ctypes`{.interpreted-text role="mod"}, `termios`{.interpreted-text role="mod"}, and `fcntl`{.interpreted-text role="mod"}, as well as experimental support for the new `default interactive shell `{.interpreted-text role="ref"}. (Contributed by R. Hood Chatham in `127146`{.interpreted-text role="gh"}, `127683`{.interpreted-text role="gh"}, and `136931`{.interpreted-text role="gh"}.) - Official Android binary releases are now provided on [python.org](https://www.python.org/downloads/android/). - GNU Autoconf 2.72 is now required to generate `configure`{.interpreted-text role="file"}. (Contributed by Erlend Aasland in `115765`{.interpreted-text role="gh"}.) - `wasm32-unknown-emscripten` is now a `11`{.interpreted-text role="pep"} tier 3 platform. (Contributed by R. Hood Chatham in `127146`{.interpreted-text role="gh"}, `127683`{.interpreted-text role="gh"}, and `136931`{.interpreted-text role="gh"}.) - `#pragma`-based linking with `python3*.lib` can now be switched off with `Py_NO_LINK_LIB`{.interpreted-text role="c:expr"}. (Contributed by Jean-Christophe Fillion-Robin in `82909`{.interpreted-text role="gh"}.) - CPython now enables a set of recommended compiler options by default for improved security. Use the `--disable-safety`{.interpreted-text role="option"} `configure`{.interpreted-text role="file"} option to disable them, or the `--enable-slower-safety`{.interpreted-text role="option"} option for a larger set of compiler options, albeit with a performance cost. - The `WITH_FREELISTS` macro and `--without-freelists` `configure`{.interpreted-text role="file"} option have been removed. - The new `configure`{.interpreted-text role="file"} option `--with-tail-call-interp`{.interpreted-text role="option"} may be used to enable the experimental tail call interpreter. See `whatsnew314-tail-call-interpreter`{.interpreted-text role="ref"} for further details. - To disable the new remote debugging support, use the `--without-remote-debug`{.interpreted-text role="option"} `configure`{.interpreted-text role="file"} option. This may be useful for security reasons. - iOS and macOS apps can now be configured to redirect `stdout` and `stderr` content to the system log. (Contributed by Russell Keith-Magee in `127592`{.interpreted-text role="gh"}.) - The iOS testbed is now able to stream test output while the test is running. The testbed can also be used to run the test suite of projects other than CPython itself. (Contributed by Russell Keith-Magee in `127592`{.interpreted-text role="gh"}.) ### `build-details.json`{.interpreted-text role="file"} {#whatsnew314-build_details} Installations of Python now contain a new file, `build-details.json`{.interpreted-text role="file"}. This is a static JSON document containing build details for CPython, to allow for introspection without needing to run code. This is helpful for use-cases such as Python launchers, cross-compilation, and so on. `build-details.json`{.interpreted-text role="file"} must be installed in the platform-independent standard library directory. This corresponds to the `'stdlib' `{.interpreted-text role="ref"} `sysconfig`{.interpreted-text role="mod"} installation path, which can be found by running `sysconfig.get_path('stdlib')`. ::: seealso `739`{.interpreted-text role="pep"} \-- `build-details.json` 1.0 \-- a static description file for Python build details ::: ### Discontinuation of PGP signatures {#whatsnew314-no-more-pgp} PGP (Pretty Good Privacy) signatures will not be provided for releases of Python 3.14 or future versions. To verify CPython artifacts, users must use [Sigstore verification materials](https://www.python.org/downloads/metadata/sigstore/). Releases have been signed using [Sigstore](https://www.sigstore.dev/) since Python 3.11. This change in release process was specified in `761`{.interpreted-text role="pep"}. ### Free-threaded Python is officially supported {#whatsnew314-free-threaded-now-supported} The free-threaded build of Python is now supported and no longer experimental. This is the start of [phase II](https://discuss.python.org/t/37075) where free-threaded Python is officially supported but still optional. The free-threading team are confident that the project is on the right path, and appreciate the continued dedication from everyone working to make free-threading ready for broader adoption across the Python community. With these recommendations and the acceptance of this PEP, the Python developer community should broadly advertise that free-threading is a supported Python build option now and into the future, and that it will not be removed without a proper deprecation schedule. Any decision to transition to [phase III](https://discuss.python.org/t/37075), with free-threading as the default or sole build of Python is still undecided, and dependent on many factors both within CPython itself and the community. This decision is for the future. ::: seealso `779`{.interpreted-text role="pep"} [PEP 779\'s acceptance](https://discuss.python.org/t/84319/123) ::: ### Binary releases for the experimental just-in-time compiler {#whatsnew314-jit-compiler} The official macOS and Windows release binaries now include an *experimental* just-in-time (JIT) compiler. Although it is **not** recommended for production use, it can be tested by setting `PYTHON_JIT=1 `{.interpreted-text role="envvar"} as an environment variable. Downstream source builds and redistributors can use the `--enable-experimental-jit=yes-off`{.interpreted-text role="option"} configuration option for similar behavior. The JIT is at an early stage and still in active development. As such, the typical performance impact of enabling it can range from 10% slower to 20% faster, depending on workload. To aid in testing and evaluation, a set of introspection functions has been provided in the `sys._jit`{.interpreted-text role="data"} namespace. `sys._jit.is_available`{.interpreted-text role="func"} can be used to determine if the current executable supports JIT compilation, while `sys._jit.is_enabled`{.interpreted-text role="func"} can be used to tell if JIT compilation has been enabled for the current process. Currently, the most significant missing functionality is that native debuggers and profilers like `gdb` and `perf` are unable to unwind through JIT frames (Python debuggers and profilers, like `pdb`{.interpreted-text role="mod"} or `profile`{.interpreted-text role="mod"}, continue to work without modification). Free-threaded builds do not support JIT compilation. Please report any bugs or major performance regressions that you encounter! ::: seealso `744`{.interpreted-text role="pep"} ::: ## Porting to Python 3.14 This section lists previously described changes and other bugfixes that may require changes to your code. ### Changes in the Python API - On Unix platforms other than macOS, *forkserver* is now the default `start method `{.interpreted-text role="ref"} for `multiprocessing`{.interpreted-text role="mod"} and `~concurrent.futures.ProcessPoolExecutor`{.interpreted-text role="class"}, instead of *fork*. See `(1) `{.interpreted-text role="ref"} and `(2) `{.interpreted-text role="ref"} for details. If you encounter `NameError`{.interpreted-text role="exc"}s or pickling errors coming out of `multiprocessing`{.interpreted-text role="mod"} or `concurrent.futures`{.interpreted-text role="mod"}, see the `forkserver restrictions `{.interpreted-text role="ref"}. This change does not affect Windows or macOS, where `'spawn' `{.interpreted-text role="ref"} remains the default start method. - `functools.partial`{.interpreted-text role="class"} is now a method descriptor. Wrap it in `staticmethod`{.interpreted-text role="func"} if you want to preserve the old behavior. (Contributed by Serhiy Storchaka and Dominykas Grigonis in `121027`{.interpreted-text role="gh"}.) - The `garbage collector is now incremental `{.interpreted-text role="ref"}, which means that the behavior of `gc.collect`{.interpreted-text role="func"} changes slightly: - `gc.collect(1)`: Performs an increment of garbage collection, rather than collecting generation 1. - Other calls to `!gc.collect`{.interpreted-text role="func"} are unchanged. - The `locale.nl_langinfo`{.interpreted-text role="func"} function now temporarily sets the `LC_CTYPE` locale in some cases. This temporary change affects other threads. (Contributed by Serhiy Storchaka in `69998`{.interpreted-text role="gh"}.) - `types.UnionType`{.interpreted-text role="class"} is now an alias for `typing.Union`{.interpreted-text role="class"}, causing changes in some behaviors. See `above `{.interpreted-text role="ref"} for more details. (Contributed by Jelle Zijlstra in `105499`{.interpreted-text role="gh"}.) - The runtime behavior of annotations has changed in various ways; see `above `{.interpreted-text role="ref"} for details. While most code that interacts with annotations should continue to work, some undocumented details may behave differently. - As part of making the `mimetypes`{.interpreted-text role="mod"} CLI public, it now exits with `1` on failure instead of `0` and `2` on incorrect command-line parameters instead of `1`. Error messages are now printed to stderr. - The `\B` pattern in regular expression now matches the empty string when given as the entire pattern, which may cause behavioural changes. - On FreeBSD, `sys.platform`{.interpreted-text role="data"} no longer contains the major version number. ### Changes in annotations (`649`{.interpreted-text role="pep"} and `749`{.interpreted-text role="pep"}) {#whatsnew314-porting-annotations} This section contains guidance on changes that may be needed to annotations or Python code that interacts with or introspects annotations, due to the changes related to `deferred evaluation of annotations `{.interpreted-text role="ref"}. In the majority of cases, working code from older versions of Python will not require any changes. #### Implications for annotated code If you define annotations in your code (for example, for use with a static type checker), then this change probably does not affect you: you can keep writing annotations the same way you did with previous versions of Python. You will likely be able to remove quoted strings in annotations, which are frequently used for forward references. Similarly, if you use `from __future__ import annotations` to avoid having to write strings in annotations, you may well be able to remove that import once you support only Python 3.14 and newer. However, if you rely on third-party libraries that read annotations, those libraries may need changes to support unquoted annotations before they work as expected. #### Implications for readers of `__annotations__` If your code reads the `~object.__annotations__`{.interpreted-text role="attr"} attribute on objects, you may want to make changes in order to support code that relies on deferred evaluation of annotations. For example, you may want to use `annotationlib.get_annotations`{.interpreted-text role="func"} with the `~annotationlib.Format.FORWARDREF`{.interpreted-text role="attr"} format, as the `dataclasses`{.interpreted-text role="mod"} module now does. The external `typing_extensions`{.interpreted-text role="pypi"} package provides partial backports of some of the functionality of the `annotationlib`{.interpreted-text role="mod"} module, such as the `~annotationlib.Format`{.interpreted-text role="class"} enum and the `~annotationlib.get_annotations`{.interpreted-text role="func"} function. These can be used to write cross-version code that takes advantage of the new behavior in Python 3.14. #### Related changes The changes in Python 3.14 are designed to rework how `!__annotations__`{.interpreted-text role="attr"} works at runtime while minimizing breakage to code that contains annotations in source code and to code that reads `!__annotations__`{.interpreted-text role="attr"}. However, if you rely on undocumented details of the annotation behavior or on private functions in the standard library, there are many ways in which your code may not work in Python 3.14. To safeguard your code against future changes, only use the documented functionality of the `annotationlib`{.interpreted-text role="mod"} module. In particular, do not read annotations directly from the namespace dictionary attribute of type objects. Use `annotationlib.get_annotate_from_class_namespace`{.interpreted-text role="func"} during class construction and `annotationlib.get_annotations`{.interpreted-text role="func"} afterwards. In previous releases, it was sometimes possible to access class annotations from an instance of an annotated class. This behavior was undocumented and accidental, and will no longer work in Python 3.14. #### `from __future__ import annotations` In Python 3.7, `563`{.interpreted-text role="pep"} introduced the `from __future__ import annotations` `future statement `{.interpreted-text role="ref"}, which turns all annotations into strings. However, this statement is now deprecated and it is expected to be removed in a future version of Python. This removal will not happen until after Python 3.13 reaches its end of life in 2029, being the last version of Python without support for deferred evaluation of annotations. In Python 3.14, the behavior of code using `from __future__ import annotations` is unchanged. ### Changes in the C API - `Py_Finalize`{.interpreted-text role="c:func"} now deletes all interned strings. This is backwards incompatible to any C extension that holds onto an interned string after a call to `Py_Finalize`{.interpreted-text role="c:func"} and is then reused after a call to `Py_Initialize`{.interpreted-text role="c:func"}. Any issues arising from this behavior will normally result in crashes during the execution of the subsequent call to `Py_Initialize`{.interpreted-text role="c:func"} from accessing uninitialized memory. To fix, use an address sanitizer to identify any use-after-free coming from an interned string and deallocate it during module shutdown. (Contributed by Eddie Elizondo in `113601`{.interpreted-text role="gh"}.) - The `Unicode Exception Objects `{.interpreted-text role="ref"} C API now raises a `TypeError`{.interpreted-text role="exc"} if its exception argument is not a `UnicodeError`{.interpreted-text role="exc"} object. (Contributed by Bénédikt Tran in `127691`{.interpreted-text role="gh"}.) ::: {#whatsnew314-refcount} - The interpreter internally avoids some reference count modifications when loading objects onto the operands stack by `borrowing `{.interpreted-text role="term"} references when possible. This can lead to smaller reference count values compared to previous Python versions. C API extensions that checked `Py_REFCNT`{.interpreted-text role="c:func"} of `1` to determine if an function argument is not referenced by any other code should instead use `PyUnstable_Object_IsUniqueReferencedTemporary`{.interpreted-text role="c:func"} as a safer replacement. - Private functions promoted to public C APIs: - `_PyBytes_Join()`: `PyBytes_Join`{.interpreted-text role="c:func"} - `_PyLong_IsNegative()`: `PyLong_IsNegative`{.interpreted-text role="c:func"} - `_PyLong_IsPositive()`: `PyLong_IsPositive`{.interpreted-text role="c:func"} - `_PyLong_IsZero()`: `PyLong_IsZero`{.interpreted-text role="c:func"} - `_PyLong_Sign()`: `PyLong_GetSign`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_Dealloc()`: `PyUnicodeWriter_Discard`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_Finish()`: `PyUnicodeWriter_Finish`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_Init()`: use `PyUnicodeWriter_Create`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_Prepare()`: (no replacement) - `_PyUnicodeWriter_PrepareKind()`: (no replacement) - `_PyUnicodeWriter_WriteChar()`: `PyUnicodeWriter_WriteChar`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_WriteStr()`: `PyUnicodeWriter_WriteStr`{.interpreted-text role="c:func"} - `_PyUnicodeWriter_WriteSubstring()`: `PyUnicodeWriter_WriteSubstring`{.interpreted-text role="c:func"} - `_PyUnicode_EQ()`: `PyUnicode_Equal`{.interpreted-text role="c:func"} - `_PyUnicode_Equal()`: `PyUnicode_Equal`{.interpreted-text role="c:func"} - `_Py_GetConfig()`: `PyConfig_Get`{.interpreted-text role="c:func"} and `PyConfig_GetInt`{.interpreted-text role="c:func"} - `_Py_HashBytes()`: `Py_HashBuffer`{.interpreted-text role="c:func"} - `_Py_fopen_obj()`: `Py_fopen`{.interpreted-text role="c:func"} - `PyMutex_IsLocked()` : `PyMutex_IsLocked`{.interpreted-text role="c:func"} The [pythoncapi-compat project](https://github.com/python/pythoncapi-compat/) can be used to get most of these new functions on Python 3.13 and older. :::