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.

注釈

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.)

• 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().

  • rmtree() recursively removes a directory tree, like shutil.rmtree().

  (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.)

symtable

• Expose the following symtable.Symbol methods:

  • is_free_class()

  • is_comp_iter()

  • is_comp_cell()

  (Contributed by Bénédikt Tran in gh-120029.)

pickle

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

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

• 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.)

• 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.)

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

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.)

Removed

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