What's New In Python 3.14

Editor:

TBD

This article explains the new features in Python 3.14, compared to 3.13.

For full details, see the changelog.

Note

Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.14 moves towards release, so it's worth checking back even after reading earlier versions.

Summary -- Release highlights

New Features

Other Language Changes

• Incorrect usage of await and asynchronous comprehensions is now detected even if the code is optimized away by the -O command line option. For example, python -O -c 'assert await 1' now produces a SyntaxError. (Contributed by Jelle Zijlstra in gh-121637.)

• Writes to __debug__ are now detected even if the code is optimized away by the -O command line option. For example, python -O -c 'assert (__debug__ := 1)' now produces a SyntaxError. (Contributed by Irit Katriel in gh-122245.)

• Added class methods float.from_number() and complex.from_number() to convert a number to float or complex type correspondingly. They raise an error if the argument is a string. (Contributed by Serhiy Storchaka in gh-84978.)

New Modules

• None yet.

Improved Modules

ast

• Added ast.compare() for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in bpo-15987.)

• Add support for copy.replace() for AST nodes.

  (Contributed by Bénédikt Tran in gh-121141.)

fractions

Added support for converting any objects that have the as_integer_ratio() method to a Fraction. (Contributed by Serhiy Storchaka in gh-82017.)

json

Add notes for JSON serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in gh-122163.)

os

• Added the os.environ.refresh() method to update os.environ with changes to the environment made by os.putenv(), by os.unsetenv(), or made outside Python in the same process. (Contributed by Victor Stinner in gh-120057.)

pathlib

• Add methods to pathlib.Path to recursively copy or remove files:

  • copy() copies the content of one file to another, like shutil.copyfile().

  • copytree() copies one directory tree to another, like shutil.copytree().

  • delete() removes a file or directory tree.

  (Contributed by Barney Gale in gh-73991.)

pdb

• Hard-coded breakpoints (breakpoint() and pdb.set_trace()) now reuse the most recent Pdb instance that calls set_trace(), instead of creating a new one each time. As a result, all the instance specific data like display and commands are preserved across hard-coded breakpoints. (Contributed by Tian Gao in gh-121450.)

pickle

• Set the default protocol version on the pickle module to 5. For more details, please see pickle protocols.

symtable

• Expose the following symtable.Symbol methods:

  • is_free_class()

  • is_comp_iter()

  • is_comp_cell()

  (Contributed by Bénédikt Tran in gh-120029.)

Optimizations

asyncio

• asyncio now uses double linked list implementation for native tasks which speeds up execution by 10% on standard pyperformance benchmarks and reduces memory usage. (Contributed by Kumar Aditya in gh-107803.)

Deprecated

• builtins: Passing a complex number as the real or imag argument in the complex() constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)

• os: Soft deprecate os.popen() and os.spawn* functions. They should no longer be used to write new code. The subprocess module is recommended instead. (Contributed by Victor Stinner in gh-120743.)

• symtable: Deprecate symtable.Class.get_methods() due to the lack of interest. (Contributed by Bénédikt Tran in gh-119698.)

Pending Removal in Python 3.15

• http.server.CGIHTTPRequestHandler will be removed along with its related --cgi flag to python -m http.server. It was obsolete and rarely used. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.

• locale: locale.getdefaultlocale() was deprecated in Python 3.11 and originally planned for removal in Python 3.13 (gh-90817), but removal has been postponed to Python 3.15. Use locale.setlocale(), locale.getencoding() and locale.getlocale() instead. (Contributed by Hugo van Kemenade in gh-111187.)

• pathlib: pathlib.PurePath.is_reserved() is deprecated and scheduled for removal in Python 3.15. Use os.path.isreserved() to detect reserved paths on Windows.

• platform: java_ver() is deprecated and will be removed in 3.15. It was largely untested, had a confusing API, and was only useful for Jython support. (Contributed by Nikita Sobolev in gh-116349.)

• threading: Passing any arguments to threading.RLock() is now deprecated. C version allows any numbers of args and kwargs, but they are just ignored. Python version does not allow any arguments. All arguments will be removed from threading.RLock() in Python 3.15. (Contributed by Nikita Sobolev in gh-102029.)

• typing.NamedTuple:

  • The undocumented keyword argument syntax for creating NamedTuple classes (NT = NamedTuple("NT", x=int)) is deprecated, and will be disallowed in 3.15. Use the class-based syntax or the functional syntax instead.

  • When using the functional syntax to create a NamedTuple class, failing to pass a value to the fields parameter (NT = NamedTuple("NT")) is deprecated. Passing None to the fields parameter (NT = NamedTuple("NT", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []).

• typing.TypedDict: When using the functional syntax to create a TypedDict class, failing to pass a value to the fields parameter (TD = TypedDict("TD")) is deprecated. Passing None to the fields parameter (TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}).

• wave: Deprecate the getmark(), setmark() and getmarkers() methods of the wave.Wave_read and wave.Wave_write classes. They will be removed in Python 3.15. (Contributed by Victor Stinner in gh-105096.)

Pending Removal in Python 3.16

• array: array.array 'u' type (wchar_t): use the 'w' type instead (Py_UCS4).

• symtable: Deprecate symtable.Class.get_methods() due to the lack of interest. (Contributed by Bénédikt Tran in gh-119698.)

Pending Removal in Future Versions

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

• argparse: Nesting argument groups and nesting mutually exclusive groups are deprecated.

• array's 'u' format code (gh-57281)

• builtins:

  • ~bool, bitwise inversion on bool.

  • bool(NotImplemented).

  • Generators: throw(type, exc, tb) and athrow(type, exc, tb) signature is deprecated: use throw(exc) and athrow(exc) instead, the single argument signature.

  • Currently Python accepts numeric literals immediately followed by keywords, for example 0in x, 1or x, 0if 1else 2. It allows confusing and ambiguous expressions like [0x1for x in y] (which can be interpreted as [0x1 for x in y] or [0x1f or x in y]). A syntax warning is raised if the numeric literal is immediately followed by one of keywords and, else, for, if, in, is and or. In a future release it will be changed to a syntax error. (gh-87999)

  • Support for __index__() and __int__() method returning non-int type: these methods will be required to return an instance of a strict subclass of int.

  • Support for __float__() method returning a strict subclass of float: these methods will be required to return an instance of float.

  • Support for __complex__() method returning a strict subclass of complex: these methods will be required to return an instance of complex.

  • Delegation of int() to __trunc__() method.

  • Passing a complex number as the real or imag argument in the complex() constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)

• calendar: calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY. (Contributed by Prince Roshan in gh-103636.)

• codeobject.co_lnotab: use the codeobject.co_lines() method instead.

• datetime:

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

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

• gettext: Plural value must be an integer.

• importlib:

  • load_module() method: use exec_module() instead.

  • cache_from_source() debug_override parameter is deprecated: use the optimization parameter instead.

• importlib.metadata:

  • EntryPoints tuple interface.

  • Implicit None on return values.

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

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

• pydoc.ErrorDuringImport: A tuple value for exc_info parameter is deprecated, use an exception instance.

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

• sre_compile, sre_constants and sre_parse modules.

• shutil: rmtree()'s onerror parameter is deprecated in Python 3.12; use the onexc parameter instead.

• ssl options and protocols:

  • ssl.SSLContext without protocol argument is deprecated.

  • ssl.SSLContext: set_npn_protocols() and selected_npn_protocol() are deprecated: use ALPN instead.

  • ssl.OP_NO_SSL* options

  • ssl.OP_NO_TLS* options

  • ssl.PROTOCOL_SSLv3

  • ssl.PROTOCOL_TLS

  • ssl.PROTOCOL_TLSv1

  • ssl.PROTOCOL_TLSv1_1

  • ssl.PROTOCOL_TLSv1_2

  • ssl.TLSVersion.SSLv3

  • ssl.TLSVersion.TLSv1

  • ssl.TLSVersion.TLSv1_1

• sysconfig.is_python_build() check_home parameter is deprecated and ignored.

• threading methods:

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

  • threading.Event.isSet(): use is_set().

  • threading.Thread.isDaemon(), threading.Thread.setDaemon(): use threading.Thread.daemon attribute.

  • threading.Thread.getName(), threading.Thread.setName(): use threading.Thread.name attribute.

  • threading.currentThread(): use threading.current_thread().

  • threading.activeCount(): use threading.active_count().

• typing.Text (gh-92332).

• unittest.IsolatedAsyncioTestCase: it is deprecated to return a value that is not None from a test case.

• urllib.parse deprecated functions: urlparse() instead

  • splitattr()

  • splithost()

  • splitnport()

  • splitpasswd()

  • splitport()

  • splitquery()

  • splittag()

  • splittype()

  • splituser()

  • splitvalue()

  • to_bytes()

• urllib.request: URLopener and FancyURLopener style of invoking requests is deprecated. Use newer urlopen() functions and methods.

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

• xml.etree.ElementTree: Testing the truth value of an Element is deprecated. In a future release it will always return True. Prefer explicit len(elem) or elem is not None tests instead.

• zipimport.zipimporter.load_module() is deprecated: use exec_module() instead.

Removed

argparse

• Remove the type, choices, and metavar parameters of argparse.BooleanOptionalAction. They were deprecated since 3.12.

ast

• Remove the following classes. They were all deprecated since Python 3.8, and have emitted deprecation warnings since Python 3.12:

  • ast.Num

  • ast.Str

  • ast.Bytes

  • ast.NameConstant

  • ast.Ellipsis

  Use ast.Constant instead. As a consequence of these removals, user-defined visit_Num, visit_Str, visit_Bytes, visit_NameConstant and visit_Ellipsis methods on custom ast.NodeVisitor subclasses will no longer be called when the NodeVisitor subclass is visiting an AST. Define a visit_Constant method instead.

  Also, remove the following deprecated properties on ast.Constant, which were present for compatibility with the now-removed AST classes:

  • ast.Constant.n

  • ast.Constant.s

  Use ast.Constant.value instead.

  (Contributed by Alex Waygood in gh-119562.)

asyncio

• Remove the following classes and functions. They were all deprecated and emitted deprecation warnings since Python 3.12:

  • asyncio.AbstractChildWatcher

  • asyncio.SafeChildWatcher

  • asyncio.MultiLoopChildWatcher

  • asyncio.FastChildWatcher

  • asyncio.ThreadedChildWatcher

  • asyncio.PidfdChildWatcher

  • asyncio.AbstractEventLoopPolicy.get_child_watcher()

  • asyncio.AbstractEventLoopPolicy.set_child_watcher()

  • asyncio.get_child_watcher()

  • asyncio.set_child_watcher()

  (Contributed by Kumar Aditya in gh-120804.)

collections.abc

• Remove collections.abc.ByteString. It had previously raised a DeprecationWarning since Python 3.12.

email

• Remove the isdst parameter from email.utils.localtime(). (Contributed by Hugo van Kemenade in gh-118798.)

importlib

• Remove deprecated importlib.abc classes:

  • importlib.abc.ResourceReader

  • importlib.abc.Traversable

  • importlib.abc.TraversableResources

  Use importlib.resources.abc classes instead:

  • importlib.resources.abc.Traversable

  • importlib.resources.abc.TraversableResources

  (Contributed by Jason R. Coombs and Hugo van Kemenade in gh-93963.)

itertools

• Remove itertools support for copy, deepcopy, and pickle operations. These had previously raised a DeprecationWarning since Python 3.12. (Contributed by Raymond Hettinger in gh-101588.)

pathlib

• Remove support for passing additional keyword arguments to pathlib.Path. In previous versions, any such arguments are ignored.

• Remove support for passing additional positional arguments to pathlib.PurePath.relative_to() and is_relative_to(). In previous versions, any such arguments are joined onto other.

pty

• Remove deprecated pty.master_open() and pty.slave_open(). They had previously raised a DeprecationWarning since Python 3.12. Use pty.openpty() instead. (Contributed by Nikita Sobolev in gh-118824.)

sqlite3

• Remove version and version_info from sqlite3. (Contributed by Hugo van Kemenade in gh-118924.)

• Disallow using a sequence of parameters with named placeholders. This had previously raised a DeprecationWarning since Python 3.12; it will now raise a sqlite3.ProgrammingError. (Contributed by Erlend E. Aasland in gh-118928 and gh-101693.)

typing

• Remove typing.ByteString. It had previously raised a DeprecationWarning since Python 3.12.

urllib

• Remove deprecated Quoter class from urllib.parse. It had previously raised a DeprecationWarning since Python 3.11. (Contributed by Nikita Sobolev in gh-118827.)

Others

• Using NotImplemented in a boolean context will now raise a TypeError. It had previously raised a DeprecationWarning since Python 3.9. (Contributed by Jelle Zijlstra in gh-118767.)

• The int() built-in no longer delegates to __trunc__(). Classes that want to support conversion to integer must implement either __int__() or __index__(). (Contributed by Mark Dickinson in gh-119743.)

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

• functools.partial is now a method descriptor. Wrap it in staticmethod() if you want to preserve the old behavior. (Contributed by Serhiy Storchaka and Dominykas Grigonis in gh-121027.)

Build Changes

C API Changes

New Features

• Add PyLong_GetSign() function to get the sign of int objects. (Contributed by Sergey B Kirpichev in gh-116560.)

• Add a new PyUnicodeWriter API to create a Python str object:

  • PyUnicodeWriter_Create().

  • PyUnicodeWriter_Discard().

  • PyUnicodeWriter_Finish().

  • PyUnicodeWriter_WriteChar().

  • PyUnicodeWriter_WriteUTF8().

  • PyUnicodeWriter_WriteUCS4().

  • PyUnicodeWriter_WriteWideChar().

  • PyUnicodeWriter_WriteStr().

  • PyUnicodeWriter_WriteRepr().

  • PyUnicodeWriter_WriteSubstring().

  • PyUnicodeWriter_Format().

  • PyUnicodeWriter_DecodeUTF8Stateful().

  (Contributed by Victor Stinner in gh-119182.)

Porting to Python 3.14

• In the limited C API 3.14 and newer, Py_TYPE() is now implemented as an opaque function call to hide implementation details. (Contributed by Victor Stinner in gh-120600.)

Deprecated

• Macros Py_IS_NAN, Py_IS_INFINITY and Py_IS_FINITE are soft deprecated, use instead isnan, isinf and isfinite available from math.h since C99. (Contributed by Sergey B Kirpichev in gh-119613.)

Pending Removal in Python 3.15

• The bundled copy of libmpdecimal.

• PyImport_ImportModuleNoBlock(): use PyImport_ImportModule() instead.

• PyWeakref_GET_OBJECT(): use PyWeakref_GetRef() instead.

• PyWeakref_GetObject(): use PyWeakref_GetRef() instead.

• Py_UNICODE_WIDE type: use wchar_t instead.

• Py_UNICODE type: use wchar_t instead.

• Python initialization functions:

  • PySys_ResetWarnOptions(): clear sys.warnoptions and warnings.filters instead.

  • Py_GetExecPrefix(): get sys.exec_prefix instead.

  • Py_GetPath(): get sys.path instead.

  • Py_GetPrefix(): get sys.prefix instead.

  • Py_GetProgramFullPath(): get sys.executable instead.

  • Py_GetProgramName(): get sys.executable instead.

  • Py_GetPythonHome(): get PyConfig.home or the PYTHONHOME environment variable instead.

Pending Removal in Future Versions

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

• Py_TPFLAGS_HAVE_FINALIZE: unneeded since Python 3.8.

• PyErr_Fetch(): use PyErr_GetRaisedException() instead.

• PyErr_NormalizeException(): use PyErr_GetRaisedException() instead.

• PyErr_Restore(): use PyErr_SetRaisedException() instead.

• PyModule_GetFilename(): use PyModule_GetFilenameObject() instead.

• PyOS_AfterFork(): use PyOS_AfterFork_Child() instead.

• PySlice_GetIndicesEx(): use PySlice_Unpack() and PySlice_AdjustIndices() instead.

• PyUnicode_AsDecodedObject(): use PyCodec_Decode() instead.

• PyUnicode_AsDecodedUnicode(): use PyCodec_Decode() instead.

• PyUnicode_AsEncodedObject(): use PyCodec_Encode() instead.

• PyUnicode_AsEncodedUnicode(): use PyCodec_Encode() instead.

• PyUnicode_READY(): unneeded since Python 3.12

• PyErr_Display(): use PyErr_DisplayException() instead.

• _PyErr_ChainExceptions(): use _PyErr_ChainExceptions1 instead.

• PyBytesObject.ob_shash member: call PyObject_Hash() instead.

• PyDictObject.ma_version_tag member.

• Thread Local Storage (TLS) API:

  • PyThread_create_key(): use PyThread_tss_alloc() instead.

  • PyThread_delete_key(): use PyThread_tss_free() instead.

  • PyThread_set_key_value(): use PyThread_tss_set() instead.

  • PyThread_get_key_value(): use PyThread_tss_get() instead.

  • PyThread_delete_key_value(): use PyThread_tss_delete() instead.

  • PyThread_ReInitTLS(): unneeded since Python 3.7.

Removed

• Creating immutable types with mutable bases was deprecated since 3.12 and now raises a TypeError.