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¶
PEP 649: deferred evaluation of annotations¶
The annotations on functions, classes, and modules are no longer evaluated eagerly. Instead, annotations are stored in special-purpose annotate functions and evaluated only when necessary. This is specified in PEP 649 and PEP 749.
This change is designed to make annotations in Python more performant and more usable in most circumstances. The runtime cost for defining annotations is minimized, but it remains possible to introspect annotations at runtime. It is usually no longer necessary to enclose annotations in strings if they contain forward references.
The new annotationlib
module provides tools for inspecting deferred
annotations. Annotations may be evaluated in the VALUE
format (which evaluates annotations to runtime values, similar to the behavior in
earlier Python versions), the FORWARDREF
format
(which replaces undefined names with special markers), and the
STRING
format (which returns annotations as strings).
This example shows how these formats behave:
>>> 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')}
>>> get_annotations(func, format=Format.STRING)
{'arg': 'Undefined'}
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. 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 __annotations__
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()
with the FORWARDREF
format, as the dataclasses
module now does.
from __future__ import annotations
¶
In Python 3.7, PEP 563 introduced the from __future__ import annotations
directive, which turns all annotations into strings. This directive is now
considered deprecated and it is expected to be removed in a future version of Python.
However, this removal will not happen until after Python 3.13, the last version of
Python without deferred evaluation of annotations, reaches its end of life in 2029.
In Python 3.14, the behavior of code using from __future__ import annotations
is unchanged.
Improved error messages¶
When unpacking assignment fails due to incorrect number of variables, the error message prints the received number of values in more cases than before. (Contributed by Tushar Sadhwani in gh-122239.)
>>> x, y, z = 1, 2, 3, 4 Traceback (most recent call last): File "<stdin>", line 1, in <module> x, y, z = 1, 2, 3, 4 ^^^^^^^ ValueError: too many values to unpack (expected 3, got 4)
PEP 741: Python Configuration C API¶
Add a PyInitConfig C API to configure the Python initialization without relying on C structures and the ability to make ABI-compatible changes in the future.
Complete the PEP 587 PyConfig C API by adding
PyInitConfig_AddModule()
which can be used to add a built-in extension
module; feature previously referred to as the “inittab”.
Add PyConfig_Get()
and PyConfig_Set()
functions to get and set
the current runtime configuration.
PEP 587 “Python Initialization Configuration” unified all the ways to configure the Python initialization. This PEP unifies also the configuration of the Python preinitialization and the Python 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 simplify the API further.
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 gh-107954.)
See also
Other language changes¶
The
map()
built-in now has an optional keyword-only strict flag likezip()
to check that all the iterables are of equal length. (Contributed by Wannes Boeykens in gh-119793.)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 aSyntaxError
. (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 aSyntaxError
. (Contributed by Irit Katriel in gh-122245.)Add class methods
float.from_number()
andcomplex.from_number()
to convert a number tofloat
orcomplex
type correspondingly. They raise an error if the argument is a string. (Contributed by Serhiy Storchaka in gh-84978.)Implement mixed-mode arithmetic rules combining real and complex numbers as specified by C standards since C99. (Contributed by Sergey B Kirpichev in gh-69639.)
All Windows code pages are now supported as “cpXXX” codecs on Windows. (Contributed by Serhiy Storchaka in gh-123803.)
super
objects are nowpickleable
andcopyable
. (Contributed by Serhiy Storchaka in gh-125767.)The
memoryview
type now supports subscription, making it a generic type. (Contributed by Brian Schubert in gh-126012.)
New modules¶
annotationlib
: For introspecting annotations. See PEP 749 for more details. (Contributed by Jelle Zijlstra in gh-119180.)
Improved modules¶
argparse¶
The default value of the program name for
argparse.ArgumentParser
now reflects the way the Python interpreter was instructed to find the__main__
module code. (Contributed by Serhiy Storchaka and Alyssa Coghlan in gh-66436.)Introduced the optional suggest_on_error parameter to
argparse.ArgumentParser
, enabling suggestions for argument choices and subparser names if mistyped by the user. (Contributed by Savannah Ostrowski in gh-124456.)
ast¶
Add
ast.compare()
for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in gh-60191.)Add support for
copy.replace()
for AST nodes. (Contributed by Bénédikt Tran in gh-121141.)Docstrings are now removed from an optimized AST in optimization level 2. (Contributed by Irit Katriel in gh-123958.)
The
repr()
output for AST nodes now includes more information. (Contributed by Tomas R in gh-116022.)
concurrent.futures¶
Add
InterpreterPoolExecutor
, which exposes “subinterpreters (multiple Python interpreters in the same process) to Python code. This is separate from the proposed API in PEP 734. (Contributed by Eric Snow in gh-124548.)The default
ProcessPoolExecutor
start method (see Contexts and start methods) changed from fork to forkserver on platforms other than macOS & Windows. If you require the threading incompatible fork start method you must explicitly request it by supplying a mp_context toconcurrent.futures.ProcessPoolExecutor
. (Contributed by Gregory P. Smith in gh-84559.)
ctypes¶
The layout of bit fields in
Structure
andUnion
now matches platform defaults (GCC/Clang or MVSC) more closely. In particular, fields no longer overlap. (Contributed by Matthias Görgens in gh-97702.)The
Structure._layout_
class attribute can now be set to help match a non-default ABI. (Contributed by Petr Viktorin in gh-97702.)On Windows, the
COMError
exception is now public. (Contributed by Jun Komoda in gh-126686.)On Windows, the
CopyComPointer()
function is now public. (Contributed by Jun Komoda in gh-127275.)
datetime¶
Add
datetime.time.strptime()
anddatetime.date.strptime()
. (Contributed by Wannes Boeykens in gh-41431.)
decimal¶
Add alternative
Decimal
constructorDecimal.from_number()
. (Contributed by Serhiy Storchaka in gh-121798.)
dis¶
Add support for rendering full source location information of
instructions
, rather than only the line number. This feature is added to the following interfaces via the show_positions keyword argument:This feature is also exposed via
dis --show-positions
. (Contributed by Bénédikt Tran in gh-123165.)Add the
dis --specialized
command-line option to show specialized bytecode. (Contributed by Bénédikt Tran in gh-127413.)
errno¶
Add
errno.EHWPOISON
error code. (Contributed by James Roy in gh-126585.)
fractions¶
Add support for converting any objects that have the
as_integer_ratio()
method to aFraction
. (Contributed by Serhiy Storchaka in gh-82017.)Add alternative
Fraction
constructorFraction.from_number()
. (Contributed by Serhiy Storchaka in gh-121797.)
functools¶
Add support to
functools.partial()
andfunctools.partialmethod()
forfunctools.Placeholder
sentinels to reserve a place for positional arguments. (Contributed by Dominykas Grigonis in gh-119127.)Allow the initial parameter of
functools.reduce()
to be passed as a keyword argument. (Contributed by Sayandip Dutta in gh-125916.)
getopt¶
http¶
Directory lists and error pages generated by the
http.server
module allow the browser to apply its default dark mode. (Contributed by Yorik Hansen in gh-123430.)
inspect¶
inspect.signature()
takes a new argument annotation_format to control theannotationlib.Format
used for representing annotations. (Contributed by Jelle Zijlstra in gh-101552.)inspect.Signature.format()
takes a new argument unquote_annotations. If true, string annotations are displayed without surrounding quotes. (Contributed by Jelle Zijlstra in gh-101552.)Add function
inspect.ispackage()
to determine whether an object is a package or not. (Contributed by Zhikang Yan in gh-125634.)
io¶
Reading text from a non-blocking stream with
read
may now raise aBlockingIOError
if the operation cannot immediately return bytes. (Contributed by Giovanni Siragusa in gh-109523.)
json¶
Add notes for JSON serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in gh-122163.)
Enable the
json
module to work as a script using the-m
switch: python -m json. See the JSON command-line interface documentation. (Contributed by Trey Hunner in gh-122873.)
mimetypes¶
Add MS and RFC 8081 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
(Contributed by Sahil Prajapati and Hugo van Kemenade in gh-84852.)
Add RFC 9559 MIME types for Matroska audiovisual data container structures, containing:
audio with no video:
audio/matroska
(.mka
)video:
video/matroska
(.mkv
)stereoscopic video:
video/matroska-3d
(.mk3d
)
(Contributed by Hugo van Kemenade in gh-89416.)
Add MIME types for images with RFCs:
RFC 1494: CCITT Group 3 (
.g3
)RFC 3362: Real-time Facsimile, T.38 (
.t38
)RFC 3745: JPEG 2000 (
.jp2
), extension (.jpx
) and compound (.jpm
)RFC 3950: Tag Image File Format Fax eXtended, TIFF-FX (
.tfx
)RFC 4047: Flexible Image Transport System (
.fits
)RFC 7903: Enhanced Metafile (
.emf
) and Windows Metafile (.wmf
)
(Contributed by Hugo van Kemenade in gh-85957.)
multiprocessing¶
The default start method (see Contexts and start methods) changed from fork to forkserver on platforms other than macOS & Windows where it was already spawn. If you require the threading incompatible fork start method you must explicitly request it using a context from
multiprocessing.get_context()
(preferred) or change the default viamultiprocessing.set_start_method()
. (Contributed by Gregory P. Smith in gh-84559.)multiprocessing
’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 gh-97514.)The multiprocessing proxy objects for list and dict types gain previously overlooked missing methods:
clear()
andcopy()
for proxies oflist
.fromkeys()
,reversed(d)
,d | {}
,{} | d
,d |= {'b': 2}
for proxies ofdict
.
(Contributed by Roy Hyunjin Han for gh-103134.)
operator¶
Two new functions
operator.is_none()
andoperator.is_not_none()
have been added, such thatoperator.is_none(obj)
is equivalent toobj is None
andoperator.is_not_none(obj)
is equivalent toobj is not None
. (Contributed by Raymond Hettinger and Nico Mexis in gh-115808.)
os¶
Add the
os.reload_environ()
function to updateos.environ
andos.environb
with changes to the environment made byos.putenv()
, byos.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 move files and directories:copy()
copies a file or directory tree to a destination.copy_into()
copies into a destination directory.move()
moves a file or directory tree to a destination.move_into()
moves into a destination directory.
(Contributed by Barney Gale in gh-73991.)
pdb¶
Hardcoded breakpoints (
breakpoint()
andpdb.set_trace()
) now reuse the most recentPdb
instance that callsset_trace()
, instead of creating a new one each time. As a result, all the instance specific data likedisplay
andcommands
are preserved across hardcoded breakpoints. (Contributed by Tian Gao in gh-121450.)Add a new argument mode to
pdb.Pdb
. Disable therestart
command whenpdb
is ininline
mode. (Contributed by Tian Gao in gh-123757.)
platform¶
Add
platform.invalidate_caches()
to invalidate the cached results.(Contributed by Bénédikt Tran in gh-122549.)
pickle¶
Set the default protocol version on the
pickle
module to 5. For more details, see pickle protocols.Add notes for pickle serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in gh-122213.)
pydoc¶
Annotations in help output are now usually displayed in a format closer to that in the original source. (Contributed by Jelle Zijlstra in gh-101552.)
symtable¶
Expose the following
symtable.Symbol
methods:(Contributed by Bénédikt Tran in gh-120029.)
sys¶
The previously undocumented special function
sys.getobjects()
, which only exists in specialized builds of Python, may now return objects from other interpreters than the one it’s called in.
tkinter¶
Make tkinter widget methods
after()
andafter_idle()
accept arguments passed by keyword. (Contributed by Zhikang Yan in gh-126899.)
unicodedata¶
The Unicode database has been updated to Unicode 16.0.0.
unittest¶
unittest
output is now colored by default. This can be controlled via thePYTHON_COLORS
environment variable as well as the canonicalNO_COLOR
andFORCE_COLOR
environment variables. See also Controlling color. (Contributed by Hugo van Kemenade in gh-127221.)unittest discovery supports namespace package as start directory again. It was removed in Python 3.11. (Contributed by Jacob Walls in gh-80958.)
uuid¶
Add support for UUID version 8 via
uuid.uuid8()
as specified in RFC 9562. (Contributed by Bénédikt Tran in gh-89083.)
Optimizations¶
asyncio¶
io¶
io
which provides the built-inopen()
makes less system calls when opening regular files as well as reading whole files. Reading a small operating system cached file in full is up to 15% faster.pathlib.Path.read_bytes()
has the most optimizations for reading a file’s bytes in full. (Contributed by Cody Maloney and Victor Stinner in gh-120754 and gh-90102.)
Deprecated¶
-
Passing the undocumented keyword argument prefix_chars to
add_argument_group()
is now deprecated. (Contributed by Savannah Ostrowski in gh-125563.)Deprecated the
argparse.FileType
type converter. Anything with resource management should be done downstream after the arguments are parsed. (Contributed by Serhiy Storchaka in gh-58032.)
asyncio
:asyncio.iscoroutinefunction()
is deprecated and will be removed in Python 3.16, useinspect.iscoroutinefunction()
instead. (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)builtins
: Passing a complex number as the real or imag argument in thecomplex()
constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)os
: Soft deprecateos.popen()
andos.spawn*
functions. They should no longer be used to write new code. Thesubprocess
module is recommended instead. (Contributed by Victor Stinner in gh-120743.)symtable
: Deprecatesymtable.Class.get_methods()
due to the lack of interest. (Contributed by Bénédikt Tran in gh-119698.)urllib.parse
: Accepting objects with false values (like0
and[]
) except empty strings, byte-like objects andNone
inurllib.parse
functionsparse_qsl()
andparse_qs()
is now deprecated. (Contributed by Serhiy Storchaka in gh-116897.)
Pending removal in Python 3.15¶
The import system:
Setting
__cached__
on a module while failing to set__spec__.cached
is deprecated. In Python 3.15,__cached__
will cease to be set or take into consideration by the import system or standard library. (gh-97879)Setting
__package__
on a module while failing to set__spec__.parent
is deprecated. In Python 3.15,__package__
will cease to be set or take into consideration by the import system or standard library. (gh-97879)
-
The undocumented
ctypes.SetPointerType()
function has been deprecated since Python 3.13.
-
The obsolete and rarely used
CGIHTTPRequestHandler
has been deprecated since Python 3.13. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.The
--cgi
flag to the python -m http.server command-line interface has been deprecated since Python 3.13.
-
The
getdefaultlocale()
function has been deprecated since Python 3.11. Its removal was originally planned for Python 3.13 (gh-90817), but has been postponed to Python 3.15. Usegetlocale()
,setlocale()
, andgetencoding()
instead. (Contributed by Hugo van Kemenade in gh-111187.)
-
PurePath.is_reserved()
has been deprecated since Python 3.13. Useos.path.isreserved()
to detect reserved paths on Windows.
-
java_ver()
has been deprecated since Python 3.13. This function is only useful for Jython support, has a confusing API, and is largely untested.
-
RLock()
will take no arguments in Python 3.15. Passing any arguments has been deprecated since Python 3.14, as the Python version does not permit any arguments, but the C version allows any number of positional or keyword arguments, ignoring every argument.
-
types.CodeType
: Accessingco_lnotab
was deprecated in PEP 626 since 3.10 and was planned to be removed in 3.12, but it only got a properDeprecationWarning
in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in gh-101866.)
-
The undocumented keyword argument syntax for creating
NamedTuple
classes (for example,Point = NamedTuple("Point", x=int, y=int)
) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead.The
typing.no_type_check_decorator()
decorator function has been deprecated since Python 3.13. After eight years in thetyping
module, it has yet to be supported by any major type checker.
wave
:The
getmark()
,setmark()
, andgetmarkers()
methods of theWave_read
andWave_write
classes have been deprecated since Python 3.13.
Pending removal in Python 3.16¶
The import system:
Setting
__loader__
on a module while failing to set__spec__.loader
is deprecated. In Python 3.16,__loader__
will cease to be set or taken into consideration by the import system or the standard library.
-
The
'u'
format code (wchar_t
) has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use the'w'
format code (Py_UCS4
) for Unicode characters instead.
-
asyncio.iscoroutinefunction()
is deprecated and will be removed in Python 3.16, useinspect.iscoroutinefunction()
instead. (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)
-
Bitwise inversion on boolean types,
~True
or~False
has been deprecated since Python 3.12, as it produces surprising and unintuitive results (-2
and-1
). Usenot x
instead for the logical negation of a Boolean. In the rare case that you need the bitwise inversion of the underlying integer, convert toint
explicitly (~int(x)
).
-
The
ExecError
exception has been deprecated since Python 3.14. It has not been used by any function inshutil
since Python 3.4, and is now an alias ofRuntimeError
.
-
The
Class.get_methods
method has been deprecated since Python 3.14.
sys
:The
_enablelegacywindowsfsencoding()
function has been deprecated since Python 3.13. Use thePYTHONLEGACYWINDOWSFSENCODING
environment variable instead.
-
The undocumented and unused
TarFile.tarfile
attribute has been deprecated since Python 3.13.
Pending removal in future versions¶
The following APIs will be removed in the future, although there is currently no date scheduled for their removal.
-
Nesting argument groups and nesting mutually exclusive groups are deprecated.
Passing the undocumented keyword argument prefix_chars to
add_argument_group()
is now deprecated.The
argparse.FileType
type converter is deprecated.
-
bool(NotImplemented)
.Generators:
throw(type, exc, tb)
andathrow(type, exc, tb)
signature is deprecated: usethrow(exc)
andathrow(exc)
instead, the single argument signature.Currently Python accepts numeric literals immediately followed by keywords, for example
0in x
,1or x
,0if 1else 2
. It allows confusing and ambiguous expressions like[0x1for x in y]
(which can be interpreted as[0x1 for x in y]
or[0x1f or x in y]
). A syntax warning is raised if the numeric literal is immediately followed by one of keywordsand
,else
,for
,if
,in
,is
andor
. In a future release it will be changed to a syntax error. (gh-87999)Support for
__index__()
and__int__()
method returning non-int type: these methods will be required to return an instance of a strict subclass ofint
.Support for
__float__()
method returning a strict subclass offloat
: these methods will be required to return an instance offloat
.Support for
__complex__()
method returning a strict subclass ofcomplex
: these methods will be required to return an instance ofcomplex
.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
andcalendar.February
constants are deprecated and replaced bycalendar.JANUARY
andcalendar.FEBRUARY
. (Contributed by Prince Roshan in gh-103636.)codeobject.co_lnotab
: use thecodeobject.co_lines()
method instead.-
utcnow()
: usedatetime.datetime.now(tz=datetime.UTC)
.utcfromtimestamp()
: usedatetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC)
.
gettext
: Plural value must be an integer.-
load_module()
method: useexec_module()
instead.cache_from_source()
debug_override parameter is deprecated: use the optimization parameter instead.
-
EntryPoints
tuple interface.Implicit
None
on return values.
logging
: thewarn()
method has been deprecated since Python 3.3, usewarning()
instead.mailbox
: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.os
: Callingos.register_at_fork()
in multi-threaded process.pydoc.ErrorDuringImport
: A tuple value for exc_info parameter is deprecated, use an exception instance.re
: More strict rules are now applied for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore. (Contributed by Serhiy Storchaka in gh-91760.)sre_compile
,sre_constants
andsre_parse
modules.shutil
:rmtree()
’s onerror parameter is deprecated in Python 3.12; use the onexc parameter instead.ssl
options and protocols:ssl.SSLContext
without protocol argument is deprecated.ssl.SSLContext
:set_npn_protocols()
andselected_npn_protocol()
are deprecated: use ALPN instead.ssl.OP_NO_SSL*
optionsssl.OP_NO_TLS*
optionsssl.PROTOCOL_SSLv3
ssl.PROTOCOL_TLS
ssl.PROTOCOL_TLSv1
ssl.PROTOCOL_TLSv1_1
ssl.PROTOCOL_TLSv1_2
ssl.TLSVersion.SSLv3
ssl.TLSVersion.TLSv1
ssl.TLSVersion.TLSv1_1
sysconfig.is_python_build()
check_home parameter is deprecated and ignored.threading
methods:threading.Condition.notifyAll()
: usenotify_all()
.threading.Event.isSet()
: useis_set()
.threading.Thread.isDaemon()
,threading.Thread.setDaemon()
: usethreading.Thread.daemon
attribute.threading.Thread.getName()
,threading.Thread.setName()
: usethreading.Thread.name
attribute.threading.currentThread()
: usethreading.current_thread()
.threading.activeCount()
: usethreading.active_count()
.
unittest.IsolatedAsyncioTestCase
: it is deprecated to return a value that is notNone
from a test case.urllib.parse
deprecated functions:urlparse()
insteadsplitattr()
splithost()
splitnport()
splitpasswd()
splitport()
splitquery()
splittag()
splittype()
splituser()
splitvalue()
to_bytes()
wsgiref
:SimpleHandler.stdout.write()
should not do partial writes.xml.etree.ElementTree
: Testing the truth value of anElement
is deprecated. In a future release it will always returnTrue
. Prefer explicitlen(elem)
orelem is not None
tests instead.zipimport.zipimporter.load_module()
is deprecated: useexec_module()
instead.
Removed¶
argparse¶
Remove the type, choices, and metavar parameters of
argparse.BooleanOptionalAction
. They were deprecated since 3.12.Calling
add_argument_group()
on an argument group, and callingadd_argument_group()
oradd_mutually_exclusive_group()
on a mutually exclusive group now raise exceptions. 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 gh-127186.)
ast¶
Remove the following classes. They were all deprecated since Python 3.8, and have emitted deprecation warnings since Python 3.12:
ast.Bytes
ast.Ellipsis
ast.NameConstant
ast.Num
ast.Str
Use
ast.Constant
instead. As a consequence of these removals, user-definedvisit_Num
,visit_Str
,visit_Bytes
,visit_NameConstant
andvisit_Ellipsis
methods on customast.NodeVisitor
subclasses will no longer be called when theNodeVisitor
subclass is visiting an AST. Define avisit_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.get_child_watcher()
asyncio.set_child_watcher()
asyncio.AbstractEventLoopPolicy.get_child_watcher()
asyncio.AbstractEventLoopPolicy.set_child_watcher()
asyncio.AbstractChildWatcher
asyncio.FastChildWatcher
asyncio.MultiLoopChildWatcher
asyncio.PidfdChildWatcher
asyncio.SafeChildWatcher
asyncio.ThreadedChildWatcher
(Contributed by Kumar Aditya in gh-120804.)
Removed implicit creation of event loop by
asyncio.get_event_loop()
. It now raises aRuntimeError
if there is no current event loop. (Contributed by Kumar Aditya in gh-126353.)
collections.abc¶
Remove
collections.abc.ByteString
. It had previously raised aDeprecationWarning
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:(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 aDeprecationWarning
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()
andis_relative_to()
. In previous versions, any such arguments are joined onto other.
pkgutil¶
Remove deprecated
pkgutil.get_loader()
andpkgutil.find_loader()
. These had previously raised aDeprecationWarning
since Python 3.12. (Contributed by Bénédikt Tran in gh-97850.)
pty¶
Remove deprecated
pty.master_open()
andpty.slave_open()
. They had previously raised aDeprecationWarning
since Python 3.12. Usepty.openpty()
instead. (Contributed by Nikita Sobolev in gh-118824.)
sqlite3¶
Remove
version
andversion_info
fromsqlite3
. (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 asqlite3.ProgrammingError
. (Contributed by Erlend E. Aasland in gh-118928 and gh-101693.)
typing¶
Remove
typing.ByteString
. It had previously raised aDeprecationWarning
since Python 3.12.
urllib¶
Remove deprecated
Quoter
class fromurllib.parse
. It had previously raised aDeprecationWarning
since Python 3.11. (Contributed by Nikita Sobolev in gh-118827.)Remove deprecated
URLopener
andFancyURLopener
classes fromurllib.request
. They had previously raised aDeprecationWarning
since Python 3.3.myopener.open()
can be replaced withurlopen()
, andmyopener.retrieve()
can be replaced withurlretrieve()
. Customizations to the opener classes can be replaced by passing customized handlers tobuild_opener()
.(Contributed by Barney Gale in gh-84850.)
Others¶
Using
NotImplemented
in a boolean context will now raise aTypeError
. It had previously raised aDeprecationWarning
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 instaticmethod()
if you want to preserve the old behavior. (Contributed by Serhiy Storchaka and Dominykas Grigonis in gh-121027.)The
locale.nl_langinfo()
function now sets temporarily theLC_CTYPE
locale in some cases. This temporary change affects other threads. (Contributed by Serhiy Storchaka in gh-69998.)
Build changes¶
PEP 761: Discontinuation of PGP signatures¶
PGP signatures will not be available for CPython 3.14 and onwards. Users verifying artifacts must use Sigstore verification materials for verifying CPython artifacts. This change in release process is specified in PEP 761.
C API changes¶
New features¶
Add
PyLong_GetSign()
function to get the sign ofint
objects. (Contributed by Sergey B Kirpichev in gh-116560.)Add a new
PyUnicodeWriter
API to create a Pythonstr
object:(Contributed by Victor Stinner in gh-119182.)
Add
PyIter_NextItem()
to replacePyIter_Next()
, which has an ambiguous return value. (Contributed by Irit Katriel and Erlend Aasland in gh-105201.)Py_Finalize()
now deletes all interned strings. This is backwards incompatible to any C-Extension that holds onto an interned string after a call toPy_Finalize()
and is then reused after a call toPy_Initialize()
. Any issues arising from this behavior will normally result in crashes during the execution of the subsequent call toPy_Initialize()
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 gh-113601.)Add
PyLong_IsPositive()
,PyLong_IsNegative()
andPyLong_IsZero()
for checking ifPyLongObject
is positive, negative, or zero, respectively. (Contributed by James Roy and Sergey B Kirpichev in gh-126061.)Add new functions to convert C
<stdint.h>
numbers from/to Pythonint
:(Contributed by Victor Stinner in gh-120389.)
Add
PyBytes_Join(sep, iterable)
function, similar tosep.join(iterable)
in Python. (Contributed by Victor Stinner in gh-121645.)Add
Py_HashBuffer()
to compute and return the hash value of a buffer. (Contributed by Antoine Pitrou and Victor Stinner in gh-122854.)Add functions to get and set the current runtime Python configuration (PEP 741):
(Contributed by Victor Stinner in gh-107954.)
Add functions to configure the Python initialization (PEP 741):
(Contributed by Victor Stinner in gh-107954.)
Add
PyType_GetBaseByToken()
andPy_tp_token
slot for easier superclass identification, which attempts to resolve the type checking issue mentioned in PEP 630 (gh-124153).Add
PyUnicode_Equal()
function to the limited C API: test if two strings are equal. (Contributed by Victor Stinner in gh-124502.)Add
PyType_Freeze()
function to make a type immutable. (Contributed by Victor Stinner in gh-121654.)Add
PyUnstable_Object_EnableDeferredRefcount()
for enabling deferred reference counting, as outlined in PEP 703.
Porting to Python 3.14¶
In the limited C API 3.14 and newer,
Py_TYPE()
andPy_REFCNT()
are now implemented as an opaque function call to hide implementation details. (Contributed by Victor Stinner in gh-120600 and gh-124127.)
Deprecated¶
The
Py_HUGE_VAL
macro is soft deprecated, usePy_INFINITY
instead. (Contributed by Sergey B Kirpichev in gh-120026.)Macros
Py_IS_NAN
,Py_IS_INFINITY
andPy_IS_FINITE
are soft deprecated, use insteadisnan
,isinf
andisfinite
available frommath.h
since C99. (Contributed by Sergey B Kirpichev in gh-119613.)
Pending removal in Python 3.15¶
The bundled copy of
libmpdecimal
.The
PyImport_ImportModuleNoBlock()
: UsePyImport_ImportModule()
instead.PyWeakref_GetObject()
andPyWeakref_GET_OBJECT()
: UsePyWeakref_GetRef()
instead.Py_UNICODE
type and thePy_UNICODE_WIDE
macro: Usewchar_t
instead.Python initialization functions:
PySys_ResetWarnOptions()
: Clearsys.warnoptions
andwarnings.filters
instead.Py_GetExecPrefix()
: Getsys.base_exec_prefix
andsys.exec_prefix
instead.Py_GetPath()
: Getsys.path
instead.Py_GetPrefix()
: Getsys.base_prefix
andsys.prefix
instead.Py_GetProgramFullPath()
: Getsys.executable
instead.Py_GetProgramName()
: Getsys.executable
instead.Py_GetPythonHome()
: GetPyConfig.home
or thePYTHONHOME
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()
: UsePyErr_GetRaisedException()
instead.PyErr_NormalizeException()
: UsePyErr_GetRaisedException()
instead.PyErr_Restore()
: UsePyErr_SetRaisedException()
instead.PyModule_GetFilename()
: UsePyModule_GetFilenameObject()
instead.PyOS_AfterFork()
: UsePyOS_AfterFork_Child()
instead.PySlice_GetIndicesEx()
: UsePySlice_Unpack()
andPySlice_AdjustIndices()
instead.PyUnicode_AsDecodedObject()
: UsePyCodec_Decode()
instead.PyUnicode_AsDecodedUnicode()
: UsePyCodec_Decode()
instead.PyUnicode_AsEncodedObject()
: UsePyCodec_Encode()
instead.PyUnicode_AsEncodedUnicode()
: UsePyCodec_Encode()
instead.PyUnicode_READY()
: Unneeded since Python 3.12PyErr_Display()
: UsePyErr_DisplayException()
instead._PyErr_ChainExceptions()
: Use_PyErr_ChainExceptions1()
instead.PyBytesObject.ob_shash
member: callPyObject_Hash()
instead.PyDictObject.ma_version_tag
member.Thread Local Storage (TLS) API:
PyThread_create_key()
: UsePyThread_tss_alloc()
instead.PyThread_delete_key()
: UsePyThread_tss_free()
instead.PyThread_set_key_value()
: UsePyThread_tss_set()
instead.PyThread_get_key_value()
: UsePyThread_tss_get()
instead.PyThread_delete_key_value()
: UsePyThread_tss_delete()
instead.PyThread_ReInitTLS()
: Unneeded since Python 3.7.
Removed¶
Creating
immutable types
with mutable bases was deprecated since 3.12 and now raises aTypeError
.