内容表

What’s New In Python 3.12

What’s New In Python 3.12 ¶

编者 :: Adam Turner

This article explains the new features in Python 3.12, compared to 3.11. Python 3.12 was released on October 2, 2023. For full details, see the changelog .

另请参阅

PEP 693 – Python 3.12 Release Schedule

摘要 – 发行亮点 ¶

Python 3.12 is the latest stable release of the Python programming language, with a mix of changes to the language and the standard library. The library changes focus on cleaning up deprecated APIs, usability, and correctness. Of note, the distutils package has been removed from the standard library. Filesystem support in os and pathlib has seen a number of improvements, and several modules have better performance.

The language changes focus on usability, as f-strings have had many limitations removed and ‘Did you mean …’ suggestions continue to improve. The new type parameter syntax and type statement improve ergonomics for using 一般类型 and type aliases with static type checkers.

This article doesn’t attempt to provide a complete specification of all new features, but instead gives a convenient overview. For full details, you should refer to the documentation, such as the 库参考 and 语言参考 . If you want 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.

新句法特征：

PEP 695 , type parameter syntax and the type 语句

New grammar features:

PEP 701 , f-strings in the grammar

解释器改进：

PEP 684 , a unique per-interpreter GIL
PEP 669 , low impact monitoring
Improved ‘Did you mean …’ suggestions for NameError , ImportError ，和 SyntaxError exceptions

Python data model improvements:

PEP 688 ，使用缓冲协议 from Python

Significant improvements in the standard library:

The pathlib.Path class now supports subclassing
The os module received several improvements for Windows support
A command-line interface has been added to the sqlite3 模块
isinstance() checks against runtime-checkable protocols enjoy a speed up of between two and 20 times
The asyncio package has had a number of performance improvements, with some benchmarks showing a 75% speed up.
A command-line interface has been added to the uuid 模块
Due to the changes in PEP 701 , producing tokens via the tokenize module is up to 64% faster.

Security improvements:

Replace the builtin hashlib implementations of SHA1, SHA3, SHA2-384, SHA2-512, and MD5 with formally verified code from the HACL* project. These builtin implementations remain as fallbacks that are only used when OpenSSL does not provide them.

C API 改进：

PEP 697 , unstable C API tier
PEP 683 , immortal objects

CPython 实现改进：

PEP 709 , comprehension inlining
CPython support for the Linux perf profiler
Implement stack overflow protection on supported platforms

新类型特征：

PEP 692 ，使用 TypedDict to annotate **kwargs
PEP 698 , typing.override() 装饰器

Important deprecations, removals or restrictions:

PEP 623 ：移除 wstr from Unicode objects in Python’s C API, reducing the size of every str object by at least 8 bytes.
PEP 632 : Remove the distutils package. See the migration guide for advice replacing the APIs it provided. The third-party Setuptools package continues to provide distutils , if you still require it in Python 3.12 and beyond.
gh-95299 : Do not pre-install setuptools in virtual environments created with venv 。这意味着 distutils , setuptools , pkg_resources ，和 easy_install will no longer available by default; to access these run pip install setuptools 在 activated virtual environment.
The asynchat , asyncore ，和 imp modules have been removed, along with several unittest.TestCase method aliases .

新特征 ¶

PEP 695: Type Parameter Syntax ¶

Generic classes and functions under PEP 484 were declared using a verbose syntax that left the scope of type parameters unclear and required explicit declarations of variance.

PEP 695 introduces a new, more compact and explicit way to create generic classes and 函数 :

def max[T](args: Iterable[T]) -> T:
    ...
class list[T]:
    def __getitem__(self, index: int, /) -> T:
        ...
    def append(self, element: T) -> None:
        ...

In addition, the PEP introduces a new way to declare type aliases 使用 type statement, which creates an instance of TypeAliasType :

type Point = tuple[float, float]

Type aliases can also be generic :

type Point[T] = tuple[T, T]

The new syntax allows declaring TypeVarTuple and ParamSpec parameters, as well as TypeVar parameters with bounds or constraints:

type IntFunc[**P] = Callable[P, int]  # ParamSpec
type LabeledTuple[*Ts] = tuple[str, *Ts]  # TypeVarTuple
type HashableSequence[T: Hashable] = Sequence[T]  # TypeVar with bound
type IntOrStrSequence[T: (int, str)] = Sequence[T]  # TypeVar with constraints

The value of type aliases and the bound and constraints of type variables created through this syntax are evaluated only on demand (see lazy evaluation ). This means type aliases are able to refer to other types defined later in the file.

Type parameters declared through a type parameter list are visible within the scope of the declaration and any nested scopes, but not in the outer scope. For example, they can be used in the type annotations for the methods of a generic class or in the class body. However, they cannot be used in the module scope after the class is defined. See Type parameter lists for a detailed description of the runtime semantics of type parameters.

In order to support these scoping semantics, a new kind of scope is introduced, the annotation scope . Annotation scopes behave for the most part like function scopes, but interact differently with enclosing class scopes. In Python 3.13, annotations will also be evaluated in annotation scopes.

见 PEP 695 了解更多细节。

(PEP written by Eric Traut. Implementation by Jelle Zijlstra, Eric Traut, and others in gh-103764 )。

PEP 701: Syntactic formalization of f-strings ¶

PEP 701 lifts some restrictions on the usage of f-strings . Expression components inside f-strings can now be any valid Python expression, including strings reusing the same quote as the containing f-string, multi-line expressions, comments, backslashes, and unicode escape sequences. Let’s cover these in detail:

Quote reuse: in Python 3.11, reusing the same quotes as the enclosing f-string raises a SyntaxError , forcing the user to either use other available quotes (like using double quotes or triple quotes if the f-string uses single quotes). In Python 3.12, you can now do things like this:
```
>>> songs = ['Take me back to Eden', 'Alkaline', 'Ascensionism']
>>> f"This is the playlist: {", ".join(songs)}"
'This is the playlist: Take me back to Eden, Alkaline, Ascensionism'
													
```
Note that before this change there was no explicit limit in how f-strings can be nested, but the fact that string quotes cannot be reused inside the expression component of f-strings made it impossible to nest f-strings arbitrarily. In fact, this is the most nested f-string that could be written:
```
>>> f"""{f'''{f'{f"{1+1}"}'}'''}"""
'2'
														
```
As now f-strings can contain any valid Python expression inside expression components, it is now possible to nest f-strings arbitrarily:
```
>>> f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}"
'2'
															
```
Multi-line expressions and comments: In Python 3.11, f-string expressions must be defined in a single line, even if the expression within the f-string could normally span multiple lines (like literal lists being defined over multiple lines), making them harder to read. In Python 3.12 you can now define f-strings spanning multiple lines, and add inline comments:
```
>>> f"This is the playlist: {", ".join([
...     'Take me back to Eden',  # My, my, those eyes like fire
...     'Alkaline',              # Not acid nor alkaline
...     'Ascensionism'           # Take to the broken skies at last
... ])}"
'This is the playlist: Take me back to Eden, Alkaline, Ascensionism'
																
```
Backslashes and unicode characters: before Python 3.12 f-string expressions couldn’t contain any \ character. This also affected unicode escape sequences (譬如 \N{snowman} ) as these contain the \N part that previously could not be part of expression components of f-strings. Now, you can define expressions like this:
```
>>> print(f"This is the playlist: {"\n".join(songs)}")
This is the playlist: Take me back to Eden
Alkaline
Ascensionism
>>> print(f"This is the playlist: {"\N{BLACK HEART SUIT}".join(songs)}")
This is the playlist: Take me back to Eden♥Alkaline♥Ascensionism
																	
```

见 PEP 701 了解更多细节。

As a positive side-effect of how this feature has been implemented (by parsing f-strings with the PEG parser ), now error messages for f-strings are more precise and include the exact location of the error. For example, in Python 3.11, the following f-string raises a SyntaxError :

>>> my_string = f"{x z y}" + f"{1 + 1}"
  File "<stdin>", line 1
    (x z y)
     ^^^
SyntaxError: f-string: invalid syntax. Perhaps you forgot a comma?

but the error message doesn’t include the exact location of the error within the line and also has the expression artificially surrounded by parentheses. In Python 3.12, as f-strings are parsed with the PEG parser, error messages can be more precise and show the entire line:

>>> my_string = f"{x z y}" + f"{1 + 1}"
  File "<stdin>", line 1
    my_string = f"{x z y}" + f"{1 + 1}"
                   ^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?

(Contributed by Pablo Galindo, Batuhan Taskaya, Lysandros Nikolaou, Cristián Maureira-Fredes and Marta Gómez in gh-102856 . PEP written by Pablo Galindo, Batuhan Taskaya, Lysandros Nikolaou and Marta Gómez).

PEP 684: A Per-Interpreter GIL ¶

PEP 684 introduces a per-interpreter GIL , so that sub-interpreters may now be created with a unique GIL per interpreter. This allows Python programs to take full advantage of multiple CPU cores. This is currently only available through the C-API, though a Python API is anticipated for 3.13 .

Use the new Py_NewInterpreterFromConfig() function to create an interpreter with its own GIL:

PyInterpreterConfig config = {
    .check_multi_interp_extensions = 1,
    .gil = PyInterpreterConfig_OWN_GIL,
};
PyThreadState *tstate = NULL;
PyStatus status = Py_NewInterpreterFromConfig(&tstate, &config);
if (PyStatus_Exception(status)) {
    return -1;
}
/* The new interpreter is now active in the current thread. */

For further examples how to use the C-API for sub-interpreters with a per-interpreter GIL, see Modules/_xxsubinterpretersmodule.c .

(Contributed by Eric Snow in gh-104210 ，等)

PEP 669: Low impact monitoring for CPython ¶

PEP 669 defines a new API for profilers, debuggers, and other tools to monitor events in CPython. It covers a wide range of events, including calls, returns, lines, exceptions, jumps, and more. This means that you only pay for what you use, providing support for near-zero overhead debuggers and coverage tools. See sys.monitoring 了解细节。

(Contributed by Mark Shannon in gh-103082 )。

PEP 688: Making the buffer protocol accessible in Python ¶

PEP 688 introduces a way to use the 缓冲协议 from Python code. Classes that implement the __buffer__() method are now usable as buffer types.

新的 collections.abc.Buffer ABC provides a standard way to represent buffer objects, for example in type annotations. The new inspect.BufferFlags enum represents the flags that can be used to customize buffer creation. (Contributed by Jelle Zijlstra in gh-102500 )。

PEP 709: Comprehension inlining ¶

Dictionary, list, and set comprehensions are now inlined, rather than creating a new single-use function object for each execution of the comprehension. This speeds up execution of a comprehension by up to two times. See PEP 709 进一步了解细节。

Comprehension iteration variables remain isolated and don’t overwrite a variable of the same name in the outer scope, nor are they visible after the comprehension. Inlining does result in a few visible behavior changes:

There is no longer a separate frame for the comprehension in tracebacks, and tracing/profiling no longer shows the comprehension as a function call.
The symtable module will no longer produce child symbol tables for each comprehension; instead, the comprehension’s locals will be included in the parent function’s symbol table.
调用 locals() inside a comprehension now includes variables from outside the comprehension, and no longer includes the synthetic .0 variable for the comprehension “argument”.
A comprehension iterating directly over locals() (如 [k for k in locals()] ) may see “RuntimeError: dictionary changed size during iteration” when run under tracing (e.g. code coverage measurement). This is the same behavior already seen in e.g. for k in locals(): . To avoid the error, first create a list of keys to iterate over: keys = list(locals()); [k for k in keys] .

(Contributed by Carl Meyer and Vladimir Matveev in PEP 709 )。

Improved Error Messages ¶

Modules from the standard library are now potentially suggested as part of the error messages displayed by the interpreter when a NameError is raised to the top level. (Contributed by Pablo Galindo in gh-98254 )。
```
>>> sys.version_info
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'sys' is not defined. Did you forget to import 'sys'?
																	
```

Improve the error suggestion for NameError exceptions for instances. Now if a NameError is raised in a method and the instance has an attribute that’s exactly equal to the name in the exception, the suggestion will include self.<NAME> instead of the closest match in the method scope. (Contributed by Pablo Galindo in gh-99139 )。

>>> class A:
...    def __init__(self):
...        self.blech = 1
...
...    def foo(self):
...        somethin = blech
...
>>> A().foo()
Traceback (most recent call last):
  File "<stdin>", line 1
    somethin = blech
               ^^^^^
NameError: name 'blech' is not defined. Did you mean: 'self.blech'?

Improve the SyntaxError error message when the user types import x from y 而不是 from y import x . (Contributed by Pablo Galindo in gh-98931 )。

>>> import a.y.z from b.y.z
Traceback (most recent call last):
  File "<stdin>", line 1
    import a.y.z from b.y.z
    ^^^^^^^^^^^^^^^^^^^^^^^
SyntaxError: Did you mean to use 'from ... import ...' instead?

ImportError exceptions raised from failed from <module> import <name> statements now include suggestions for the value of <name> based on the available names in <module> . (Contributed by Pablo Galindo in gh-91058 )。

>>> from collections import chainmap
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'chainmap' from 'collections'. Did you mean: 'ChainMap'?

This section covers major changes affecting 类型提示 和 typing 模块。

PEP 692: Using `TypedDict` for more precise `**kwargs` typing ¶

Typing **kwargs in a function signature as introduced by PEP 484 allowed for valid annotations only in cases where all of the **kwargs were of the same type.

PEP 692 specifies a more precise way of typing **kwargs by relying on typed dictionaries:

from typing import TypedDict, Unpack
class Movie(TypedDict):
  name: str
  year: int
def foo(**kwargs: Unpack[Movie]): ...

见 PEP 692 了解更多细节。

(Contributed by Franek Magiera in gh-103629 )。

PEP 698: Override Decorator for Static Typing ¶

A new decorator typing.override() has been added to the typing module. It indicates to type checkers that the method is intended to override a method in a superclass. This allows type checkers to catch mistakes where a method that is intended to override something in a base class does not in fact do so.

范例：

from typing import override
class Base:
  def get_color(self) -> str:
    return "blue"
class GoodChild(Base):
  @override  # ok: overrides Base.get_color
  def get_color(self) -> str:
    return "yellow"
class BadChild(Base):
  @override  # type checker error: does not override Base.get_color
  def get_colour(self) -> str:
    return "red"

见 PEP 698 了解更多细节。

(Contributed by Steven Troxler in gh-101561 )。

其它语言变化 ¶

The parser now raises SyntaxError when parsing source code containing null bytes. (Contributed by Pablo Galindo in gh-96670 )。
A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning ，而不是 DeprecationWarning 。例如， re.compile("\d+\.\d+") now emits a SyntaxWarning ( "\d" is an invalid escape sequence, use raw strings for regular expression: re.compile(r"\d+\.\d+") ). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning . (Contributed by Victor Stinner in gh-98401 )。
Octal escapes with value larger than 0o377 (ex: "\477" ), deprecated in Python 3.11, now produce a SyntaxWarning ，而不是 DeprecationWarning . In a future Python version they will be eventually a SyntaxError . (Contributed by Victor Stinner in gh-98401 )。
Variables used in the target part of comprehensions that are not stored to can now be used in assignment expressions ( := ). For example, in [(b := 1) for a, b.prop in some_iter] , the assignment to b is now allowed. Note that assigning to variables stored to in the target part of comprehensions (like a ) is still disallowed, as per PEP 572 . (Contributed by Nikita Sobolev in gh-100581 )。
Exceptions raised in a class or type’s __set_name__ method are no longer wrapped by a RuntimeError . Context information is added to the exception as a PEP 678 note. (Contributed by Irit Katriel in gh-77757 )。
当 try-except* construct handles the entire ExceptionGroup and raises one other exception, that exception is no longer wrapped in an ExceptionGroup . Also changed in version 3.11.4. (Contributed by Irit Katriel in gh-103590 )。
The Garbage Collector now runs only on the eval breaker mechanism of the Python bytecode evaluation loop instead of object allocations. The GC can also run when PyErr_CheckSignals() is called so C extensions that need to run for a long time without executing any Python code also have a chance to execute the GC periodically. (Contributed by Pablo Galindo in gh-97922 )。
All builtin and extension callables expecting boolean parameters now accept arguments of any type instead of just bool and int . (Contributed by Serhiy Storchaka in gh-60203 )。
memoryview now supports the half-float type (the “e” format code). (Contributed by Donghee Na and Antoine Pitrou in gh-90751 )。
slice objects are now hashable, allowing them to be used as dict keys and set items. (Contributed by Will Bradshaw, Furkan Onder, and Raymond Hettinger in gh-101264 )。
sum() now uses Neumaier summation to improve accuracy and commutativity when summing floats or mixed ints and floats. (Contributed by Raymond Hettinger in gh-100425 )。
ast.parse() 现在引发 SyntaxError 而不是 ValueError when parsing source code containing null bytes. (Contributed by Pablo Galindo in gh-96670 )。
The extraction methods in tarfile ，和 shutil.unpack_archive() , have a new a filter argument that allows limiting tar features than may be surprising or dangerous, such as creating files outside the destination directory. See tarfile extraction filters for details. In Python 3.14, the default will switch to 'data' . (Contributed by Petr Viktorin in PEP 706 )。
types.MappingProxyType instances are now hashable if the underlying mapping is hashable. (Contributed by Serhiy Storchaka in gh-87995 )。
添加 support for the perf profiler through the new environment variable PYTHONPERFSUPPORT and command-line option -X perf , as well as the new sys.activate_stack_trampoline() , sys.deactivate_stack_trampoline() ，和 sys.is_stack_trampoline_active() functions. (Design by Pablo Galindo. Contributed by Pablo Galindo and Christian Heimes with contributions from Gregory P. Smith [Google] and Mark Shannon in gh-96123 )。

新模块 ¶

None.

改进模块 ¶

array ¶

The array.array class now supports subscripting, making it a 一般类型 . (Contributed by Jelle Zijlstra in gh-98658 )。

asyncio ¶

The performance of writing to sockets in asyncio has been significantly improved. asyncio now avoids unnecessary copying when writing to sockets and uses sendmsg() if the platform supports it. (Contributed by Kumar Aditya in gh-91166 )。
添加 asyncio.eager_task_factory() and asyncio.create_eager_task_factory() functions to allow opting an event loop in to eager task execution, making some use-cases 2x to 5x faster. (Contributed by Jacob Bower & Itamar Oren in gh-102853 , gh-104140 ，和 gh-104138 )
在 Linux， asyncio 使用 asyncio.PidfdChildWatcher by default if os.pidfd_open() is available and functional instead of asyncio.ThreadedChildWatcher . (Contributed by Kumar Aditya in gh-98024 )。
The event loop now uses the best available child watcher for each platform ( asyncio.PidfdChildWatcher if supported and asyncio.ThreadedChildWatcher otherwise), so manually configuring a child watcher is not recommended. (Contributed by Kumar Aditya in gh-94597 )。
添加 loop_factory 参数用于 asyncio.run() to allow specifying a custom event loop factory. (Contributed by Kumar Aditya in gh-99388 )。
Add C implementation of asyncio.current_task() for 4x-6x speedup. (Contributed by Itamar Oren and Pranav Thulasiram Bhat in gh-100344 )。
asyncio.iscoroutine() now returns False for generators as asyncio does not support legacy generator-based coroutines. (Contributed by Kumar Aditya in gh-102748 )。
asyncio.wait() and asyncio.as_completed() now accepts generators yielding tasks. (Contributed by Kumar Aditya in gh-78530 )。

calendar ¶

Add enums calendar.Month and calendar.Day defining months of the year and days of the week. (Contributed by Prince Roshan in gh-103636 )。

csv ¶

添加 csv.QUOTE_NOTNULL and csv.QUOTE_STRINGS flags to provide finer grained control of None and empty strings by csv.writer 对象。

dis ¶

Pseudo instruction opcodes (which are used by the compiler but do not appear in executable bytecode) are now exposed in the dis 模块。 HAVE_ARGUMENT is still relevant to real opcodes, but it is not useful for pseudo instructions. Use the new dis.hasarg collection instead. (Contributed by Irit Katriel in gh-94216 )。
添加 dis.hasexc collection to signify instructions that set an exception handler. (Contributed by Irit Katriel in gh-94216 )。

fractions ¶

Objects of type fractions.Fraction now support float-style formatting. (Contributed by Mark Dickinson in gh-100161 )。

importlib.resources ¶

importlib.resources.as_file() now supports resource directories. (Contributed by Jason R. Coombs in gh-97930 )。
Rename first parameter of importlib.resources.files() to anchor . (Contributed by Jason R. Coombs in gh-100598 )。

inspect ¶

添加 inspect.markcoroutinefunction() to mark sync functions that return a 协程用于 inspect.iscoroutinefunction() . (Contributed by Carlton Gibson in gh-99247 )。
添加 inspect.getasyncgenstate() and inspect.getasyncgenlocals() for determining the current state of asynchronous generators. (Contributed by Thomas Krennwallner in gh-79940 )。
The performance of inspect.getattr_static() has been considerably improved. Most calls to the function should be at least 2x faster than they were in Python 3.11. (Contributed by Alex Waygood in gh-103193 )。

itertools ¶

添加 itertools.batched() for collecting into even-sized tuples where the last batch may be shorter than the rest. (Contributed by Raymond Hettinger in gh-98363 )。

math ¶

添加 math.sumprod() for computing a sum of products. (Contributed by Raymond Hettinger in gh-100485 )。
Extend math.nextafter() to include a steps argument for moving up or down multiple steps at a time. (Contributed by Matthias Goergens, Mark Dickinson, and Raymond Hettinger in gh-94906 )。

os ¶

添加 os.PIDFD_NONBLOCK to open a file descriptor for a process with os.pidfd_open() in non-blocking mode. (Contributed by Kumar Aditya in gh-93312 )。
os.DirEntry now includes an os.DirEntry.is_junction() method to check if the entry is a junction. (Contributed by Charles Machalow in gh-99547 )。
添加 os.listdrives() , os.listvolumes() and os.listmounts() functions on Windows for enumerating drives, volumes and mount points. (Contributed by Steve Dower in gh-102519 )。
os.stat() and os.lstat() are now more accurate on Windows. The st_birthtime field will now be filled with the creation time of the file, and st_ctime is deprecated but still contains the creation time (but in the future will return the last metadata change, for consistency with other platforms). st_dev may be up to 64 bits and st_ino up to 128 bits depending on your file system, and st_rdev is always set to zero rather than incorrect values. Both functions may be significantly faster on newer releases of Windows. (Contributed by Steve Dower in gh-99726 )。
As of 3.12.4, os.mkdir() and os.makedirs() on Windows now support passing a mode value of 0o700 to apply access control to the new directory. This implicitly affects tempfile.mkdtemp() and is a mitigation for CVE-2024-4030 . Other values for mode continue to be ignored. (Contributed by Steve Dower in gh-118486 )。

os.path ¶

添加 os.path.isjunction() to check if a given path is a junction. (Contributed by Charles Machalow in gh-99547 )。
添加 os.path.splitroot() to split a path into a triad (drive, root, tail) . (Contributed by Barney Gale in gh-101000 )。

pathlib ¶

Add support for subclassing pathlib.PurePath and pathlib.Path , plus their Posix- and Windows-specific variants. Subclasses may override the pathlib.PurePath.with_segments() method to pass information between path instances.
添加 pathlib.Path.walk() for walking the directory trees and generating all file or directory names within them, similar to os.walk() . (Contributed by Stanislav Zmiev in gh-90385 )。
添加 walk_up optional parameter to pathlib.PurePath.relative_to() to allow the insertion of .. entries in the result; this behavior is more consistent with os.path.relpath() . (Contributed by Domenico Ragusa in gh-84538 )。
添加 pathlib.Path.is_junction() as a proxy to os.path.isjunction() . (Contributed by Charles Machalow in gh-99547 )。
添加 case_sensitive optional parameter to pathlib.Path.glob() , pathlib.Path.rglob() and pathlib.PurePath.match() for matching the path’s case sensitivity, allowing for more precise control over the matching process.

pdb ¶

Add convenience variables to hold values temporarily for debug session and provide quick access to values like the current frame or the return value. (Contributed by Tian Gao in gh-103693 )。

random ¶

添加 random.binomialvariate() . (Contributed by Raymond Hettinger in gh-81620 )。
Add a default of lambd=1.0 to random.expovariate() . (Contributed by Raymond Hettinger in gh-100234 )。

shutil ¶

shutil.make_archive() now passes the root_dir argument to custom archivers which support it. In this case it no longer temporarily changes the current working directory of the process to root_dir to perform archiving. (Contributed by Serhiy Storchaka in gh-74696 )。
shutil.rmtree() now accepts a new argument onexc which is an error handler like onerror but which expects an exception instance rather than a (typ, val, tb) triplet. onerror is deprecated. (Contributed by Irit Katriel in gh-102828 )。
shutil.which() now consults the PATHEXT environment variable to find matches within PATH on Windows even when the given cmd includes a directory component. (Contributed by Charles Machalow in gh-103179 )。

shutil.which() 将调用 NeedCurrentDirectoryForExePathW when querying for executables on Windows to determine if the current working directory should be prepended to the search path. (Contributed by Charles Machalow in gh-103179 )。

shutil.which() will return a path matching the cmd with a component from PATHEXT prior to a direct match elsewhere in the search path on Windows. (Contributed by Charles Machalow in gh-103179 )。

sqlite3 ¶

添加 command-line interface . (Contributed by Erlend E. Aasland in gh-77617 )。
添加 sqlite3.Connection.autocommit 属性为 sqlite3.Connection 和 autocommit 参数用于 sqlite3.connect() to control PEP 249 -compliant transaction handling . (Contributed by Erlend E. Aasland in gh-83638 )。
添加 entrypoint keyword-only parameter to sqlite3.Connection.load_extension() , for overriding the SQLite extension entry point. (Contributed by Erlend E. Aasland in gh-103015 )。
添加 sqlite3.Connection.getconfig() and sqlite3.Connection.setconfig() to sqlite3.Connection to make configuration changes to a database connection. (Contributed by Erlend E. Aasland in gh-103489 )。

statistics ¶

Extend statistics.correlation() to include as a ranked method for computing the Spearman correlation of ranked data. (Contributed by Raymond Hettinger in gh-95861 )。

sys ¶

添加 sys.monitoring namespace to expose the new PEP 669 monitoring API. (Contributed by Mark Shannon in gh-103082 )。
添加 sys.activate_stack_trampoline() and sys.deactivate_stack_trampoline() for activating and deactivating stack profiler trampolines, and sys.is_stack_trampoline_active() for querying if stack profiler trampolines are active. (Contributed by Pablo Galindo and Christian Heimes with contributions from Gregory P. Smith [Google] and Mark Shannon in gh-96123 )。
添加 sys.last_exc which holds the last unhandled exception that was raised (for post-mortem debugging use cases). Deprecate the three fields that have the same information in its legacy form: sys.last_type , sys.last_value and sys.last_traceback . (Contributed by Irit Katriel in gh-102778 )。
sys._current_exceptions() now returns a mapping from thread-id to an exception instance, rather than to a (typ, exc, tb) tuple. (Contributed by Irit Katriel in gh-103176 )。
sys.setrecursionlimit() and sys.getrecursionlimit() . The recursion limit now applies only to Python code. Builtin functions do not use the recursion limit, but are protected by a different mechanism that prevents recursion from causing a virtual machine crash.

tempfile ¶

The tempfile.NamedTemporaryFile function has a new optional parameter delete_on_close (Contributed by Evgeny Zorin in gh-58451 )。
tempfile.mkdtemp() now always returns an absolute path, even if the argument provided to the dir parameter is a relative path.
As of 3.12.4 on Windows, the default mode 0o700 used by tempfile.mkdtemp() now limits access to the new directory due to changes to os.mkdir() . This is a mitigation for CVE-2024-4030 。(由 Steve Dower 史蒂夫·道尔提供在 gh-118486 )。

threading ¶

添加 threading.settrace_all_threads() and threading.setprofile_all_threads() that allow to set tracing and profiling functions in all running threads in addition to the calling one. (Contributed by Pablo Galindo in gh-93503 )。

tkinter ¶

tkinter.Canvas.coords() now flattens its arguments. It now accepts not only coordinates as separate arguments ( x1, y1, x2, y2, ... ) and a sequence of coordinates ( [x1, y1, x2, y2, ...] ), but also coordinates grouped in pairs ( (x1, y1), (x2, y2), ... and [(x1, y1), (x2, y2), ...] ), like create_*() methods. (Contributed by Serhiy Storchaka in gh-94473 )。

tokenize ¶

The tokenize module includes the changes introduced in PEP 701 . (Contributed by Marta Gómez Macías and Pablo Galindo in gh-102856 .) See Porting to Python 3.12 for more information on the changes to the tokenize 模块。

类型 ¶

添加 types.get_original_bases() to allow for further introspection of 用户定义一般类型 when subclassed. (Contributed by James Hilton-Balfe and Alex Waygood in gh-101827 )。

typing ¶

isinstance() checks against runtime-checkable protocols now use inspect.getattr_static() 而不是 hasattr() to lookup whether attributes exist. This means that descriptors and __getattr__() methods are no longer unexpectedly evaluated during isinstance() checks against runtime-checkable protocols. However, it may also mean that some objects which used to be considered instances of a runtime-checkable protocol may no longer be considered instances of that protocol on Python 3.12+, and vice versa. Most users are unlikely to be affected by this change. (Contributed by Alex Waygood in gh-102433 )。
The members of a runtime-checkable protocol are now considered “frozen” at runtime as soon as the class has been created. Monkey-patching attributes onto a runtime-checkable protocol will still work, but will have no impact on isinstance() checks comparing objects to the protocol. For example:
```
>>> from typing import Protocol, runtime_checkable
>>> @runtime_checkable
... class HasX(Protocol):
...     x = 1
...
>>> class Foo: ...
...
>>> f = Foo()
>>> isinstance(f, HasX)
False
>>> f.x = 1
>>> isinstance(f, HasX)
True
>>> HasX.y = 2
>>> isinstance(f, HasX)  # unchanged, even though HasX now also has a "y" attribute
True
```
This change was made in order to speed up isinstance() checks against runtime-checkable protocols.
The performance profile of isinstance() checks against runtime-checkable protocols has changed significantly. Most isinstance() checks against protocols with only a few members should be at least 2x faster than in 3.11, and some may be 20x faster or more. However, isinstance() checks against protocols with many members may be slower than in Python 3.11. (Contributed by Alex Waygood in gh-74690 and gh-103193 )。
所有 typing.TypedDict and typing.NamedTuple classes now have the __orig_bases__ attribute. (Contributed by Adrian Garcia Badaracco in gh-103699 )。
添加 frozen_default 参数用于 typing.dataclass_transform() . (Contributed by Erik De Bonte in gh-99957 )。

unicodedata ¶

The Unicode database has been updated to version 15.0.0. (Contributed by Benjamin Peterson in gh-96734 ).

unittest ¶

添加 --durations command line option, showing the N slowest test cases:

python3 -m unittest --durations=3 lib.tests.test_threading
.....
Slowest test durations
----------------------------------------------------------------------
1.210s     test_timeout (Lib.test.test_threading.BarrierTests)
1.003s     test_default_timeout (Lib.test.test_threading.BarrierTests)
0.518s     test_timeout (Lib.test.test_threading.EventTests)
(0.000 durations hidden.  Use -v to show these durations.)
----------------------------------------------------------------------
Ran 158 tests in 9.869s
OK (skipped=3)

(Contributed by Giampaolo Rodola in gh-48330 )

uuid ¶

添加 command-line interface . (Contributed by Adam Chhina in gh-88597 )。

优化 ¶

移除 wstr and wstr_length members from Unicode objects. It reduces object size by 8 or 16 bytes on 64bit platform. ( PEP 623 ) (Contributed by Inada Naoki in gh-92536 )。
Add experimental support for using the BOLT binary optimizer in the build process, which improves performance by 1-5%. (Contributed by Kevin Modzelewski in gh-90536 and tuned by Donghee Na in gh-101525 )
Speed up the regular expression substitution (functions re.sub() and re.subn() and corresponding re.Pattern methods) for replacement strings containing group references by 2–3 times. (Contributed by Serhiy Storchaka in gh-91524 )。
Speed up asyncio.Task creation by deferring expensive string formatting. (Contributed by Itamar Oren in gh-103793 )。
The tokenize.tokenize() and tokenize.generate_tokens() functions are up to 64% faster as a side effect of the changes required to cover PEP 701 在 tokenize module. (Contributed by Marta Gómez Macías and Pablo Galindo in gh-102856 )。
Speed up super() method calls and attribute loads via the new LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and Vladimir Matveev in gh-103497 )。

CPython 字节码变化 ¶

Remove the LOAD_METHOD instruction. It has been merged into LOAD_ATTR . LOAD_ATTR will now behave like the old LOAD_METHOD instruction if the low bit of its oparg is set. (Contributed by Ken Jin in gh-93429 )。
Remove the JUMP_IF_FALSE_OR_POP and JUMP_IF_TRUE_OR_POP instructions. (Contributed by Irit Katriel in gh-102859 )。
Remove the PRECALL instruction. (Contributed by Mark Shannon in gh-92925 )。
添加 BINARY_SLICE and STORE_SLICE instructions. (Contributed by Mark Shannon in gh-94163 )。
添加 CALL_INTRINSIC_1 instructions. (Contributed by Mark Shannon in gh-99005 )。
添加 CALL_INTRINSIC_2 instruction. (Contributed by Irit Katriel in gh-101799 )。
添加 CLEANUP_THROW instruction. (Contributed by Brandt Bucher in gh-90997 )。
添加 END_SEND instruction. (Contributed by Mark Shannon in gh-103082 )。
添加 LOAD_FAST_AND_CLEAR instruction as part of the implementation of PEP 709 . (Contributed by Carl Meyer in gh-101441 )。
添加 LOAD_FAST_CHECK instruction. (Contributed by Dennis Sweeney in gh-93143 )。
添加 LOAD_FROM_DICT_OR_DEREF , LOAD_FROM_DICT_OR_GLOBALS ，和 LOAD_LOCALS opcodes as part of the implementation of PEP 695 . Remove the LOAD_CLASSDEREF opcode, which can be replaced with LOAD_LOCALS plus LOAD_FROM_DICT_OR_DEREF . (Contributed by Jelle Zijlstra in gh-103764 )。
添加 LOAD_SUPER_ATTR instruction. (Contributed by Carl Meyer and Vladimir Matveev in gh-103497 )。
添加 RETURN_CONST instruction. (Contributed by Wenyang Wang in gh-101632 )。

Demos and Tools ¶

Remove the Tools/demo/ directory which contained old demo scripts. A copy can be found in the old-demos project . (Contributed by Victor Stinner in gh-97681 )。
Remove outdated example scripts of the Tools/scripts/ directory. A copy can be found in the old-demos project . (Contributed by Victor Stinner in gh-97669 )。

弃用 ¶

argparse ： type , choices ，和 metavar parameters of argparse.BooleanOptionalAction are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in gh-92248 )。
ast : The following ast features have been deprecated in documentation since Python 3.8, now cause a DeprecationWarning to be emitted at runtime when they are accessed or used, and will be removed in Python 3.14:
- ast.Num
- ast.Str
- ast.Bytes
- ast.NameConstant
- ast.Ellipsis
使用 ast.Constant instead. (Contributed by Serhiy Storchaka in gh-90953 )。
asyncio :
- The child watcher classes asyncio.MultiLoopChildWatcher , asyncio.FastChildWatcher , asyncio.AbstractChildWatcher and asyncio.SafeChildWatcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597 )。
- asyncio.set_child_watcher() , asyncio.get_child_watcher() , asyncio.AbstractEventLoopPolicy.set_child_watcher() and asyncio.AbstractEventLoopPolicy.get_child_watcher() are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597 )。
- The get_event_loop() method of the default event loop policy now emits a DeprecationWarning if there is no current event loop set and it decides to create one. (Contributed by Serhiy Storchaka and Guido van Rossum in gh-100160 )。
calendar : calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY . (Contributed by Prince Roshan in gh-103636 )。
collections.abc : Deprecated collections.abc.ByteString . Prefer Sequence or collections.abc.Buffer . For use in typing, prefer a union, like bytes | bytearray ，或 collections.abc.Buffer . (Contributed by Shantanu Jain in gh-91896 )。
datetime : datetime.datetime ’s utcnow() and utcfromtimestamp() are deprecated and will be removed in a future version. Instead, use timezone-aware objects to represent datetimes in UTC: respectively, call now() and fromtimestamp() 采用 tz parameter set to datetime.UTC . (Contributed by Paul Ganssle in gh-103857 )。
email : Deprecate the isdst parameter in email.utils.localtime() . (Contributed by Alan Williams in gh-72346 )。
importlib.abc : Deprecated the following classes, scheduled for removal in Python 3.14:
- importlib.abc.ResourceReader
- importlib.abc.Traversable
- importlib.abc.TraversableResources
使用 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 : Deprecate the support for copy, deepcopy, and pickle operations, which is undocumented, inefficient, historically buggy, and inconsistent. This will be removed in 3.14 for a significant reduction in code volume and maintenance burden. (Contributed by Raymond Hettinger in gh-101588 )。
multiprocessing : In Python 3.14, the default multiprocessing start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default ( gh-84559 ). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the get_context() or set_start_method() APIs to explicitly specify when your code requires 'fork' 。见 contexts and start methods .
pkgutil : pkgutil.find_loader() and pkgutil.get_loader() are deprecated and will be removed in Python 3.14; use importlib.util.find_spec() instead. (Contributed by Nikita Sobolev in gh-97850 )。
pty : The module has two undocumented master_open() and slave_open() functions that have been deprecated since Python 2 but only gained a proper DeprecationWarning in 3.12. Remove them in 3.14. (Contributed by Soumendra Ganguly and Gregory P. Smith in gh-85984 )。
os :
- The st_ctime fields return by os.stat() and os.lstat() on Windows are deprecated. In a future release, they will contain the last metadata change time, consistent with other platforms. For now, they still contain the creation time, which is also available in the new st_birthtime field. (Contributed by Steve Dower in gh-99726 )。
- On POSIX platforms, os.fork() can now raise a DeprecationWarning when it can detect being called from a multithreaded process. There has always been a fundamental incompatibility with the POSIX platform when doing so. Even if such code appeared to work. We added the warning to raise awareness as issues encountered by code doing this are becoming more frequent. See the os.fork() documentation for more details along with this discussion on fork being incompatible with threads for why we’re now surfacing this longstanding platform compatibility problem to developers.
When this warning appears due to usage of multiprocessing or concurrent.futures the fix is to use a different multiprocessing start method such as "spawn" or "forkserver" .
shutil ： onerror 自变量 shutil.rmtree() is deprecated; use onexc instead. (Contributed by Irit Katriel in gh-102828 )。
sqlite3 :
- default adapters and converters are now deprecated. Instead, use the Adapter and converter recipes and tailor them to your needs. (Contributed by Erlend E. Aasland in gh-90016 )。
- 在 execute() , DeprecationWarning is now emitted when named placeholders are used together with parameters supplied as a sequence instead of as a dict . Starting from Python 3.14, using named placeholders with parameters supplied as a sequence will raise a ProgrammingError . (Contributed by Erlend E. Aasland in gh-101698 )。
sys ： sys.last_type , sys.last_value and sys.last_traceback fields are deprecated. Use sys.last_exc instead. (Contributed by Irit Katriel in gh-102778 )。
tarfile : Extracting tar archives without specifying filter is deprecated until Python 3.14, when 'data' filter will become the default. See Extraction filters 了解细节。
typing :
- typing.Hashable and typing.Sized , aliases for collections.abc.Hashable and collections.abc.Sized respectively, are deprecated. ( gh-94309 )。
- typing.ByteString , deprecated since Python 3.9, now causes a DeprecationWarning to be emitted when it is used. (Contributed by Alex Waygood in gh-91896 )。
xml.etree.ElementTree : The module now emits DeprecationWarning when testing the truth value of an xml.etree.ElementTree.Element . Before, the Python implementation emitted FutureWarning , and the C implementation emitted nothing. (Contributed by Jacob Walls in gh-83122 )。
The 3-arg signatures (type, value, traceback) of coroutine throw() , generator throw() and async generator throw() are deprecated and may be removed in a future version of Python. Use the single-arg versions of these functions instead. (Contributed by Ofey Chan in gh-89874 )。
DeprecationWarning is now raised when __package__ on a module differs from __spec__.parent (previously it was ImportWarning ). (Contributed by Brett Cannon in gh-65961 )。
设置 __package__ or __cached__ on a module is deprecated, and will cease to be set or taken into consideration by the import system in Python 3.14. (Contributed by Brett Cannon in gh-65961 )。
The bitwise inversion operator ( ~ ) on bool is deprecated. It will throw an error in Python 3.14. Use not for logical negation of bools instead. In the rare case that you really need the bitwise inversion of the underlying int , convert to int explicitly: ~int(x) . (Contributed by Tim Hoffmann in gh-103487 )。
访问 co_lnotab on code objects was deprecated in Python 3.10 via PEP 626 , but it only got a proper DeprecationWarning in 3.12, therefore it will be removed in 3.14. (Contributed by Nikita Sobolev in gh-101866 )。

Pending Removal in Python 3.13 ¶

The following modules and APIs have been deprecated in earlier Python releases, and will be removed in Python 3.13.

Modules (see PEP 594 ):

Other modules:

lib2to3 ，和 2to3 program ( gh-84540 )

API：

configparser.LegacyInterpolation ( gh-90765 )
locale.resetlocale() ( gh-90817 )
turtle.RawTurtle.settiltangle() ( gh-50096 )
unittest.findTestCases() ( gh-50096 )
unittest.getTestCaseNames() ( gh-50096 )
unittest.makeSuite() ( gh-50096 )
unittest.TestProgram.usageExit() ( gh-67048 )
webbrowser.MacOSX ( gh-86421 )
classmethod descriptor chaining ( gh-89519 )
importlib.resources deprecated methods:
- contents()
- is_resource()
- open_binary()
- open_text()
- path()
- read_binary()
- read_text()
使用 importlib.resources.files() instead. Refer to importlib-resources: Migrating from Legacy ( gh-106531 )

Pending Removal in Python 3.14 ¶

The following APIs have been deprecated and will be removed in Python 3.14.

argparse ： type , choices ，和 metavar parameters of argparse.BooleanOptionalAction
ast :
- ast.Num
- ast.Str
- ast.Bytes
- ast.NameConstant
- ast.Ellipsis
asyncio :
- asyncio.MultiLoopChildWatcher
- asyncio.FastChildWatcher
- asyncio.AbstractChildWatcher
- asyncio.SafeChildWatcher
- asyncio.set_child_watcher()
- asyncio.get_child_watcher() ,
- asyncio.AbstractEventLoopPolicy.set_child_watcher()
- asyncio.AbstractEventLoopPolicy.get_child_watcher()
collections.abc : collections.abc.ByteString .
email : the isdst parameter in email.utils.localtime() .
importlib.abc :
- importlib.abc.ResourceReader
- importlib.abc.Traversable
- importlib.abc.TraversableResources
itertools : Support for copy, deepcopy, and pickle operations.
pkgutil :
- pkgutil.find_loader()
- pkgutil.get_loader() .
pty :
- pty.master_open()
- pty.slave_open()
shutil ： onerror 自变量 shutil.rmtree()
typing : typing.ByteString
xml.etree.ElementTree : Testing the truth value of an xml.etree.ElementTree.Element .
The __package__ and __cached__ attributes on module objects.
The co_lnotab attribute of code objects.

Pending Removal in Python 3.15 ¶

The following APIs have been deprecated and will be removed in Python 3.15.

API：

locale.getdefaultlocale() ( gh-90817 )

Pending Removal in Future Versions ¶

The following APIs were deprecated in earlier Python versions and will be removed, although there is currently no date scheduled for their removal.

array ’s 'u' format code ( gh-57281 )
typing.Text ( gh-92332 )
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 )

移除 ¶

asynchat and asyncore ¶

These two modules have been removed according to the schedule in PEP 594 , having been deprecated in Python 3.6. Use asyncio instead. (Contributed by Nikita Sobolev in gh-96580 )。

configparser ¶

Several names deprecated in the configparser way back in 3.2 have been removed per gh-89336 :
- configparser.ParsingError no longer has a filename attribute or argument. Use the source attribute and argument instead.
- configparser no longer has a SafeConfigParser class. Use the shorter ConfigParser name instead.
- configparser.ConfigParser no longer has a readfp method. Use read_file() 代替。

distutils ¶

Remove the distutils package. It was deprecated in Python 3.10 by PEP 632 “Deprecate distutils module”. For projects still using distutils and cannot be updated to something else, the setuptools project can be installed: it still provides distutils . (Contributed by Victor Stinner in gh-92584 )。

ensurepip ¶

Remove the bundled setuptools wheel from ensurepip , and stop installing setuptools in environments created by venv .

pip (>= 22.1) does not require setuptools to be installed in the environment. setuptools -based (and distutils -based) packages can still be used with pip install , since pip will provide setuptools in the build environment it uses for building a package.

easy_install , pkg_resources , setuptools and distutils are no longer provided by default in environments created with venv or bootstrapped with ensurepip , since they are part of the setuptools package. For projects relying on these at runtime, the setuptools project should be declared as a dependency and installed separately (typically, using pip).

(Contributed by Pradyun Gedam in gh-95299 )。

enum ¶

移除 enum ’s EnumMeta.__getattr__ , which is no longer needed for enum attribute access. (Contributed by Ethan Furman in gh-95083 )。

ftplib ¶

移除 ftplib ’s FTP_TLS.ssl_version class attribute: use the context parameter instead. (Contributed by Victor Stinner in gh-94172 )。

gzip ¶

Remove the filename attribute of gzip ’s gzip.GzipFile , deprecated since Python 2.6, use the name attribute instead. In write mode, the filename attribute added '.gz' file extension if it was not present. (Contributed by Victor Stinner in gh-94196 )。

hashlib ¶

Remove the pure Python implementation of hashlib ’s hashlib.pbkdf2_hmac() , deprecated in Python 3.10. Python 3.10 and newer requires OpenSSL 1.1.1 ( PEP 644 ): this OpenSSL version provides a C implementation of pbkdf2_hmac() which is faster. (Contributed by Victor Stinner in gh-94199 )。

importlib ¶

Many previously deprecated cleanups in importlib have now been completed:
- References to, and support for module_repr() has been removed. (Contributed by Barry Warsaw in gh-97850 )。
- importlib.util.set_package , importlib.util.set_loader and importlib.util.module_for_loader have all been removed. (Contributed by Brett Cannon and Nikita Sobolev in gh-65961 and gh-97850 )。
- 支持 find_loader() and find_module() APIs have been removed. (Contributed by Barry Warsaw in gh-98040 )。
- importlib.abc.Finder , pkgutil.ImpImporter ，和 pkgutil.ImpLoader have been removed. (Contributed by Barry Warsaw in gh-98040 )。

imp ¶

The imp module has been removed. (Contributed by Barry Warsaw in gh-98040 )。

To migrate, consult the following correspondence table:

imp

importlib

imp.NullImporter

插入 None into sys.path_importer_cache

imp.cache_from_source()

importlib.util.cache_from_source()

imp.find_module()

importlib.util.find_spec()

imp.get_magic()

importlib.util.MAGIC_NUMBER

imp.get_suffixes()

importlib.machinery.SOURCE_SUFFIXES , importlib.machinery.EXTENSION_SUFFIXES ，和 importlib.machinery.BYTECODE_SUFFIXES

imp.get_tag()

sys.implementation.cache_tag

imp.load_module()

importlib.import_module()

imp.new_module(name)

types.ModuleType(name)

imp.reload()

importlib.reload()

imp.source_from_cache()

importlib.util.source_from_cache()

imp.load_source()

See below

替换 imp.load_source() 采用：
import importlib.util
import importlib.machinery
def load_source(modname, filename):
    loader = importlib.machinery.SourceFileLoader(modname, filename)
    spec = importlib.util.spec_from_file_location(modname, filename, loader=loader)
    module = importlib.util.module_from_spec(spec)
    # The module is always executed and not cached in sys.modules.
    # Uncomment the following line to cache the module.
    # sys.modules[module.__name__] = module
    loader.exec_module(module)
    return module

移除 imp functions and attributes with no replacements:
- Undocumented functions:
  - imp.init_builtin()
  - imp.load_compiled()
  - imp.load_dynamic()
  - imp.load_package()
- imp.lock_held() , imp.acquire_lock() , imp.release_lock() : the locking scheme has changed in Python 3.3 to per-module locks.
- imp.find_module() constants: SEARCH_ERROR , PY_SOURCE , PY_COMPILED , C_EXTENSION , PY_RESOURCE , PKG_DIRECTORY , C_BUILTIN , PY_FROZEN , PY_CODERESOURCE , IMP_HOOK .

io ¶

移除 io ’s io.OpenWrapper and _pyio.OpenWrapper , deprecated in Python 3.10: just use open() instead. The open() ( io.open() ) function is a built-in function. Since Python 3.10, _pyio.open() is also a static method. (Contributed by Victor Stinner in gh-94169 )。

locale ¶

移除 locale ’s locale.format() function, deprecated in Python 3.7: use locale.format_string() instead. (Contributed by Victor Stinner in gh-94226 )。

smtpd ¶

The smtpd module has been removed according to the schedule in PEP 594 , having been deprecated in Python 3.4.7 and 3.5.4. Use the aiosmtpd PyPI module or any other asyncio -based server instead. (Contributed by Oleg Iarygin in gh-93243 )。

sqlite3 ¶

The following undocumented sqlite3 features, deprecated in Python 3.10, are now removed:
- sqlite3.enable_shared_cache()
- sqlite3.OptimizedUnicode
If a shared cache must be used, open the database in URI mode using the cache=shared query parameter.

The sqlite3.OptimizedUnicode text factory has been an alias for str since Python 3.3. Code that previously set the text factory to OptimizedUnicode can either use str explicitly, or rely on the default value which is also str .

(Contributed by Erlend E. Aasland in gh-92548 )。

ssl ¶

移除 ssl ’s ssl.RAND_pseudo_bytes() function, deprecated in Python 3.6: use os.urandom() or ssl.RAND_bytes() instead. (Contributed by Victor Stinner in gh-94199 )。
Remove the ssl.match_hostname() function. It was deprecated in Python 3.7. OpenSSL performs hostname matching since Python 3.7, Python no longer uses the ssl.match_hostname() function. (Contributed by Victor Stinner in gh-94199 )。
Remove the ssl.wrap_socket() function, deprecated in Python 3.7: instead, create a ssl.SSLContext object and call its ssl.SSLContext.wrap_socket method. Any package that still uses ssl.wrap_socket() is broken and insecure. The function neither sends a SNI TLS extension nor validates the server hostname. Code is subject to CWE-295 (Improper Certificate Validation). (Contributed by Victor Stinner in gh-94199 )。

unittest ¶

Remove many long-deprecated unittest 特征：

A number of TestCase method aliases:

Deprecated alias	Method Name	Deprecated in
`failUnless`	`assertTrue()`	3.1
`failIf`	`assertFalse()`	3.1
`failUnlessEqual`	`assertEqual()`	3.1
`failIfEqual`	`assertNotEqual()`	3.1
`failUnlessAlmostEqual`	`assertAlmostEqual()`	3.1
`failIfAlmostEqual`	`assertNotAlmostEqual()`	3.1
`failUnlessRaises`	`assertRaises()`	3.1
`assert_`	`assertTrue()`	3.2
`assertEquals`	`assertEqual()`	3.2
`assertNotEquals`	`assertNotEqual()`	3.2
`assertAlmostEquals`	`assertAlmostEqual()`	3.2
`assertNotAlmostEquals`	`assertNotAlmostEqual()`	3.2
`assertRegexpMatches`	`assertRegex()`	3.2
`assertRaisesRegexp`	`assertRaisesRegex()`	3.2
`assertNotRegexpMatches`	`assertNotRegex()`	3.5

可以使用 https://github.com/isidentical/teyit to automatically modernise your unit tests.

Undocumented and broken TestCase 方法 assertDictContainsSubset (deprecated in Python 3.2).
Undocumented TestLoader.loadTestsFromModule 参数 use_load_tests (deprecated and ignored since Python 3.5).
An alias of the TextTestResult 类： _TextTestResult (deprecated in Python 3.2).

(Contributed by Serhiy Storchaka in gh-89325 )。

webbrowser ¶

Remove support for obsolete browsers from webbrowser . The removed browsers include: Grail, Mosaic, Netscape, Galeon, Skipstone, Iceape, Firebird, and Firefox versions 35 and below ( gh-102871 ).

xml.etree.ElementTree ¶

Remove the ElementTree.Element.copy() method of the pure Python implementation, deprecated in Python 3.10, use the copy.copy() function instead. The C implementation of xml.etree.ElementTree has no copy() method, only a __copy__() method. (Contributed by Victor Stinner in gh-94383 )。

zipimport ¶

移除 zipimport ’s find_loader() and find_module() methods, deprecated in Python 3.10: use the find_spec() method instead. See PEP 451 for the rationale. (Contributed by Victor Stinner in gh-94379 )。

其它 ¶

Remove the suspicious rule from the documentation Makefile and Doc/tools/rstlint.py , both in favor of sphinx-lint . (Contributed by Julien Palard in gh-98179 )。
Remove the keyfile and certfile parameters from the ftplib , imaplib , poplib and smtplib modules, and the key_file , cert_file and check_hostname parameters from the http.client module, all deprecated since Python 3.6. Use the context parameter ( ssl_context in imaplib ) instead. (Contributed by Victor Stinner in gh-94172 )。
移除 Jython compatibility hacks from several stdlib modules and tests. (Contributed by Nikita Sobolev in gh-99482 )。
移除 _use_broken_old_ctypes_structure_semantics_ flag from ctypes module. (Contributed by Nikita Sobolev in gh-99285 )。

Porting to Python 3.12 ¶

This section lists previously described changes and other bugfixes that may require changes to your code.

Python API 变化 ¶

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 )。
移除 randrange() functionality deprecated since Python 3.10. Formerly, randrange(10.0) losslessly converted to randrange(10) . Now, it raises a TypeError . Also, the exception raised for non-integer values such as randrange(10.5) or randrange('10') has been changed from ValueError to TypeError . This also prevents bugs where randrange(1e25) would silently select from a larger range than randrange(10**25) . (Originally suggested by Serhiy Storchaka gh-86388 )。
argparse.ArgumentParser changed encoding and error handler for reading arguments from file (e.g. fromfile_prefix_chars option) from default text encoding (e.g. locale.getpreferredencoding(False) ) 到文件系统编码和错误处理程序 . Argument files should be encoded in UTF-8 instead of ANSI Codepage on Windows.
Remove the asyncore -based smtpd module deprecated in Python 3.4.7 and 3.5.4. A recommended replacement is the asyncio -based aiosmtpd PyPI module.
shlex.split() : Passing None for s argument now raises an exception, rather than reading sys.stdin . The feature was deprecated in Python 3.9. (Contributed by Victor Stinner in gh-94352 )。
The os module no longer accepts bytes-like paths, like bytearray and memoryview types: only the exact bytes type is accepted for bytes strings. (Contributed by Victor Stinner in gh-98393 )。
syslog.openlog() and syslog.closelog() now fail if used in subinterpreters. syslog.syslog() may still be used in subinterpreters, but now only if syslog.openlog() has already been called in the main interpreter. These new restrictions do not apply to the main interpreter, so only a very small set of users might be affected. This change helps with interpreter isolation. Furthermore, syslog is a wrapper around process-global resources, which are best managed from the main interpreter. (Contributed by Donghee Na in gh-99127 )。
The undocumented locking behavior of cached_property() is removed, because it locked across all instances of the class, leading to high lock contention. This means that a cached property getter function could now run more than once for a single instance, if two threads race. For most simple cached properties (e.g. those that are idempotent and simply calculate a value based on other attributes of the instance) this will be fine. If synchronization is needed, implement locking within the cached property getter function or around multi-threaded access points.
sys._current_exceptions() now returns a mapping from thread-id to an exception instance, rather than to a (typ, exc, tb) tuple. (Contributed by Irit Katriel in gh-103176 )。
When extracting tar files using tarfile or shutil.unpack_archive() , pass the filter argument to limit features that may be surprising or dangerous. See Extraction filters 了解细节。
The output of the tokenize.tokenize() and tokenize.generate_tokens() functions is now changed due to the changes introduced in PEP 701 。这意味着 STRING tokens are not emitted any more for f-strings and the tokens described in PEP 701 are now produced instead: FSTRING_START , FSTRING_MIDDLE and FSTRING_END are now emitted for f-string “string” parts in addition to the appropriate tokens for the tokenization in the expression components. For example for the f-string f"start {1+1} end" the old version of the tokenizer emitted:
```
1,0-1,18:           STRING         'f"start {1+1} end"'
```
while the new version emits:
```
1,0-1,2:            FSTRING_START  'f"'
1,2-1,8:            FSTRING_MIDDLE 'start '
1,8-1,9:            OP             '{'
1,9-1,10:           NUMBER         '1'
1,10-1,11:          OP             '+'
1,11-1,12:          NUMBER         '1'
1,12-1,13:          OP             '}'
1,13-1,17:          FSTRING_MIDDLE ' end'
1,17-1,18:          FSTRING_END    '"'
```
Additionally, there may be some minor behavioral changes as a consequence of the changes required to support PEP 701 . Some of these changes include:
- The type attribute of the tokens emitted when tokenizing some invalid Python characters such as ! has changed from ERRORTOKEN to OP .
- Incomplete single-line strings now also raise tokenize.TokenError as incomplete multiline strings do.
- Some incomplete or invalid Python code now raises tokenize.TokenError instead of returning arbitrary ERRORTOKEN tokens when tokenizing it.
- Mixing tabs and spaces as indentation in the same file is not supported anymore and will raise a TabError .
The threading module now expects the _thread module to have an _is_main_interpreter attribute. It is a function with no arguments that returns True if the current interpreter is the main interpreter.

Any library or application that provides a custom _thread module should provide _is_main_interpreter() 。(见 gh-112826 )。

构建变化 ¶

Python no longer uses setup.py to build shared C extension modules. Build parameters like headers and libraries are detected in configure script. Extensions are built by Makefile . Most extensions use pkg-config and fall back to manual detection. (Contributed by Christian Heimes in gh-93939 )。
va_start() with two parameters, like va_start(args, format), is now required to build Python. va_start() is no longer called with a single parameter. (Contributed by Kumar Aditya in gh-93207 )。
CPython now uses the ThinLTO option as the default link time optimization policy if the Clang compiler accepts the flag. (Contributed by Donghee Na in gh-89536 )。
添加 COMPILEALL_OPTS variable in Makefile to override compileall options (default: -j0 ) 在 make install . Also merged the 3 compileall commands into a single command to build .pyc files for all optimization levels (0, 1, 2) at once. (Contributed by Victor Stinner in gh-99289 )。
Add platform triplets for 64-bit LoongArch:
- loongarch64-linux-gnusf
- loongarch64-linux-gnuf32
- loongarch64-linux-gnu
(Contributed by Zhang Na in gh-90656 )。
PYTHON_FOR_REGEN now require Python 3.10 or newer.
Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate !configure . (Contributed by Christian Heimes in gh-89886 )。
Windows builds and macOS installers from python.org now use OpenSSL 3.0.

C API 变化 ¶