파이썬 3.13의 새로운 기능에 대해 알아봅시다
*******************************************

편집자:
   Adam Turner and Thomas Wouters

해당하는 문서는 기존의 파이썬 3.12와 비교했을 때 파이썬 3.13의 새로운
기능들에 대해 설명합니다. 파이썬 3.13은 2024년 10월 7일에 배포되었습니
다. 배포와 관련된 전체 기록을 열람하시려면, 아래 변경 로그를 확인해주
세요.

더 보기: **PEP 719** -- 파이썬 3.13 릴리스 일정


요약 -- 릴리스 하이라이트
=========================

Python 3.13 is a stable release of the Python programming language,
with a mix of changes to the language, the implementation and the
standard library. The biggest changes include a new interactive
interpreter, experimental support for running in a free-threaded mode
(**PEP 703**), and a Just-In-Time compiler (**PEP 744**).

에러 메세지는 계속 개선되고 있습니다. 트레이스백(Traceback)들의 경우
기본적으로 색깔 표시됩니다. "locals()" 내장 함수의 경우 반환된 매핑을
변화시키기 위해 정의된 의미 구조를 활용하고, 또한 타입 매개변수들은 기
본 값의 설정을 지원합니다.

표준 라이브러리의 업데이트는, 오래되어 더 이상 지원되지 않는 API들과
모듈들의 업데이트(혹은 제거)를 포함합니다. 또한, 보다 사용자 친화적이
거나 보다 정확한 라이브러리가 되기 위한 통상적인 업데이트들을 포함합니
다. 몇몇의 오래된 레거시 표준 라이브러리 모듈들은, 파이썬 3.11 버전에
서의 사용 지원 중단(deprecate)된 이후에, 현 버전에서 제거되었습니다.

해당하는 업데이트 문서는 새로운 기능 전체에 대해서 설명을 제공해주는
것을 목적으로 삼지 않습니다. 다만, 보다 편리하게 한눈에 볼 수 있을 개
괄 설명을 제공하려는 것입니다. 보다 자세한 정보를 원하신다면, 공식 문
서를 참고해주세요; 예를 들어, 라이브러리 색인 혹은 언어 색인 등을 참고
하실 수 있습니다. 보다 구체적인 구현 원리 혹은 디자인 원칙에 대해 이해
하시고 싶으신 분들께서는, 해당하는 새로운 기능과 관련된 PEP 문서를 열
람해주시기를 부탁드립니다. 다만, PEP 문서들의 경우 통상적으로 해당하는
기능이 구현되고 난 이후에는 추가적으로 업데이트되지 않아 최신화되지 않
은 부분이 있을 수 있음을 양해 부탁드립니다. 과거 버전의 파이썬을 사용
하는 시스템을 파이썬 3.13으로 업그레이드(혹은 이식)하기 위한 안내의 경
우 Porting to Python 3.13을 참고 부탁드립니다.

======================================================================

인터프리터의 개선:

* 대화형 인터프리터와 개선된 에러 메세지에 있어 커다란 개선이 있었습니
  다.

* **PEP 667**: 기존의 "locals()" 내장 함수의 경우 새롭게 정의된 의미
  구조를 지원하며, 이러한 지원은 반환되는 매핑 구조의 변환이 필요한 경
  우에 대한 것입니다. 파이썬 디버거들 혹은 유사한 디버깅 도구들의 경우
  , 이러한 지원을 통해 지역 변수에 대한 보다 안정적인 업데이트 반영을
  보다 최적화된 범위에 대해 수행할 수 있으며, 동시적인 코드 작동 중에
  서도 마찬가지로 이러한 최적화가 가능해졌습니다.

* **PEP 703**: 파이썬 3.13은 전역 인터프리터 잠금(*global interpreter
  lock*)의 해제를 실험적으로 지원합니다. 보다 자세한 내용의 경우 제한
  없는 스레드 모드(free-threaded mode)을 참고 부탁드립니다.

* **PEP 744**: 기본적인 지정 시간 구동 (Just-In-Time) 컴파일러가 추가
  되었습니다. 현재는 기본적으로 사용하지 않으며(향후 활성화될 수 있습
  니다) 성능 개선 효과는 크지 않습니다. 향후의 릴리스들을 통해 더욱 개
  선될 예정입니다.

* 대화형 인터프리터에서 색상 지원을 추가하고, 트레이스백 및 doctest출
  력에도 적용되었습니다. 이 기능은 "PYTHON_COLORS"와 "NO_COLOR"환경 변
  수를 통해 비활성화할 수 있습니다.

파이썬 데이터 모델의 개선 사항들

* "__static_attributes__"는 클래스 본문 내 함수에서 "self.X" 형태로 액
  세스되는 속성의 이름을 저장합니다.

* "__firstlineno__"는 클래스 정의의 첫 번째 줄 번호를 기록합니다.

표준 라이브러리의 중요한 개선 사항들:

* 새로운 "PythonFinalizationError" 예외를 추가했으며, *종료 시기* 동안
  작업이 차단(block)될 때 이 예외가 발생합니다.

* "argparse" 모듈은 명령줄 옵션, 위치 인자와 하위 명령에 대한 사용 지
  원 중단(deprecating) 표시를 지원합니다.

* 새로운 함수 "base64.z85encode()"와 "base64.z85decode()"는 Z85 data의
  인코딩과 디코딩을 지원합니다.

* "copy" 모듈에 "copy.replace()" 함수가 추가되었으며, 여러 내장 타입들
  과 "__replace__()" 메서드를 정의하는 모든 클래스를 지원합니다.

* 새로운 "dbm.sqlite3" 모듈이 기본 "dbm" 백엔드가 되었습니다.

* "os" 모듈에 리눅스의 타이머 알림 파일 디스크립터로 작업할 수 있는 새
  로운 함수 세트가 추가되었습니다.

* "random" 모듈에 명령줄 인터페이스가 추가되었습니다.

보안 개선 사항들:

* "ssl.create_default_context()"가 기본 플래그로
  "ssl.VERIFY_X509_PARTIAL_CHAIN"과 "ssl.VERIFY_X509_STRICT"를 설정합
  니다.

C API 개선 사항들:

* "Py_mod_gil"슬롯은 확장 모듈이 *GIL*을 비활성화한 상태에서 실행을 지
  원한다는 것을 나타내기 위해 사용됩니다.

* 시스템 시계에 액세스를 제공하는 PyTime C API가 추가되었습니다.

* "PyMutex"는 1바이트만 차지하는 새로운 경량 뮤텍스(Mutex)입니다.

* C API에 **PEP 669** 모니터링 이벤트를 생성하는 함수 세트가 새로 추가
  되었습니다.

새로운 타이핑 기능들:

* **PEP 696**: 타입 매개변수("typing.TypeVar", "typing.ParamSpec",
  "typing.TypeVarTuple")에 기본값을 지정할 수 있도록 하는 기능을 새롭
  게 지원합니다.

* **PEP 702**: 새로운 "warnings.deprecated()" 데코레이터는 타입 시스템
  과 런타임에서 사용 지원 중단(deprecate) 예정 표시를 지원합니다.

* **PEP 705**: "typing.ReadOnly"는 "typing.TypedDict"의 항목을 타입 검
  사기에서 읽기 전용으로 표시하는 데 사용할 수 있습니다.

* **PEP 742**: "typing.TypeIs"는 "typing.TypeGuard"의 대안으로 더 직관
  적인 타입 축소(type narrowing) 동작을 제공합니다.

플랫폼 지원:

* **PEP 730**: 애플의 iOS가 공식적으로 지원되는 플랫폼으로 **3단계
  (Tier 3)** 수준에서 지원됩니다.

* **PEP 738**: Android는 공식적으로 지원되는 플랫폼으로 **3단계 (Tier
  3)** 수준에서 지원됩니다.

* "wasm32-wasi"는 **2단계 (Tier 2)** 수준에서 지원됩니다.

* "wasm32-emscripten"은 더 이상 공식적으로 지원되는 플랫폼이 아닙니다.

중요한 제거 사항들:

* PEP 594: 표준 라이브러리에서 ‘죽은 배터리(dead batteries)’로 분류된
  레거시 모듈 19개가 제거되었습니다: "aifc", "audioop", "cgi",
  "cgitb", "chunk", "crypt", "imghdr", "mailcap", "msilib", "nis",
  "nntplib", "ossaudiodev", "pipes", "sndhdr", "spwd", "sunau",
  "telnetlib", "uu", "xdrlib".

* (파이썬 3.11에서 사용 지원 중단되었던) **2to3** 도구와 "lib2to3" 모
  듈이 제거되었습니다.

* (파이썬 3.6에서 사용 지원 중단되었던) "tkinter.tix" 모듈이 제거되었
  습니다.

* "locale.resetlocale()" 함수가 제거되었습니다.

* "typing.io" 및 "typing.re" 네임스페이스들이 제거되었습니다.

* 연쇄 "classmethod" 설명자(descriptors)가 제거되었습니다.

릴리스 일정 변경 사항들:

**PEP 602** ("Annual Release Cycle for Python")는 새로운 릴리스의 완전
지원(‘버그 수정’) 기간을 2년으로 연장하도록 업데이트되었습니다. 이는
다음을 의미합니다:

* Python 3.9부터 3.12 버전까지는 완전 지원 기간이 1년 반이며, 이후 3년
  반 동안은 보안 수정만 제공됩니다.

* Python 3.13 및 이후 버전은 완전 지원 기간이 2년이며, 그 후 3년간은
  보안 수정만 제공합니다.


새로운 기능들
=============


개선된 대화형 인터프리터
------------------------

파이썬 3.13은 기본적으로 PyPy project의 코드를 기반으로 한 새로운 대화
형 (*interactive*) 셸을 사용합니다. 사용자가 대화형 터미널에서 *REPL*
을 시작하면 다음과 같은 새 기능이 지원됩니다:

* 여러개의 줄을 편집할 때에도 기록을 보존할 수 있습니다.

* "help", "exit", "quit" 같은 REPL 전용 명령을 직접 지원합니다. 또한,
  함수로 호출할 필요 없이 사용할 수 있습니다.

* 프롬프트와 트레이스백에서 기본적으로 색상이 활성화됩니다.

* "F1"으로 대화형 도움말을 탐색할 수 있으며, 별도로 명령 기록이 제공됩
  니다.

* "F2"로 명령 기록을 탐색할 때, 출력을 건너뛸 뿐 아니라 *>>>*와 *...*
  프롬프트도 건너뜁니다.

* "F3"의 "붙여넣기 모드"는 큰 코드 블록을 붙여넣기 쉽게 해 줍니다("F3"
  를 다시 누르면 일반 프롬프트로 다시 돌아갑니다).

새 대화형 셸을 비활성화하려면 "PYTHON_BASIC_REPL" 환경 변수를 설정하면
됩니다. 대화형 모드에 대한 자세한 내용은 대화형 모드을 참조 부탁드립니
다.

(PyPy 프로젝트의 코드를 기반으로, Pablo Galindo Salgado, Łukasz Langa,
Lysandros Nikolaou가 gh-111201을 통해 기능을 구현하였습니다. Dino
Viehland와 Anthony Shaw가 Windows 지원에 기여하였습니다.)


개선된 에러 메세지
------------------

* 인터프리터는 터미널에서 트레이스백을 표시할 때 기본적으로 색상을 사
  용합니다. 이러한 색상 적용을 변경하기 위해 "PYTHON_COLORS" 환경 변수
  및 "NO_COLOR" 및 "FORCE_COLOR" 환경 변수를 활용할 수 있으며, 이러한
  활용을 통해 색상 적용을 제어할 수 있습니다. (Pablo Galindo Salgado가
  gh-112730를 통해 기능을 구현하였습니다.)

* 표준 라이브러리 모듈과 동일한 이름의 스크립트를 작성하는 실수는 (여
  러 사용자에 의해) 흔히 발생합니다. 표준 라이브러리 모듈과 동일한 이
  름의 스크립트로 인해 오류가 발생하는 경우에 보다 자세한 에러 메세지
  제공함을 통해 보다 도움이 될 수 있도록 하였습니다:

     $ python random.py
     Traceback (most recent call last):
       File "/home/me/random.py", line 1, in <module>
         import random
       File "/home/me/random.py", line 3, in <module>
         print(random.randint(5))
               ^^^^^^^^^^^^^^
     AttributeError: module 'random' has no attribute 'randint' (consider renaming '/home/me/random.py' since it has the same name as the standard library module named 'random' and prevents importing that standard library module)

  또한, 스크립트가 임포트(import)하려는 제삼자(third-party) 모듈과 이
  름이 같아서 오류가 발생하는 경우에도 보다 자세한 에러 메세지 제공함
  을 통해 보다 도움이 될 수 있도록 하였습니다:

     $ python numpy.py
     Traceback (most recent call last):
       File "/home/me/numpy.py", line 1, in <module>
         import numpy as np
       File "/home/me/numpy.py", line 3, in <module>
         np.array([1, 2, 3])
         ^^^^^^^^
     AttributeError: module 'numpy' has no attribute 'array' (consider renaming '/home/me/numpy.py' if it has the same name as a library you intended to import)

  (Shantanu Jain이 gh-95754을 통해 기능을 구현하였습니다.)

* 함수에 잘못된 키워드 인자가 전달되는 경우, 올바른 키워드 인자가 에러
  메세지 안에서 제안되도록 하였습니다.

     >>> "Better error messages!".split(max_split=1)
     Traceback (most recent call last):
       File "<python-input-0>", line 1, in <module>
         "Better error messages!".split(max_split=1)
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
     TypeError: split() got an unexpected keyword argument 'max_split'. Did you mean 'maxsplit'?

  (Pablo Galindo Salgado와 Shantanu Jain이 gh-107944를 통해 기능을 구
  현하였습니다.)


제한 없는 스레드를 사용하는 파이썬(CPython)
-------------------------------------------

CPython은 *전역 인터프리터 잠금 (GIL)*을 비활성화한 제한 없는 스레드
모드(free-threaded mode)에서 실행을 실험적으로 지원합니다. 이는 실험적
기능이므로 기본 설정으로 활성화되어 있지는 않습니다. 제한 없는 스레드
모드를 실행시키기 위해서는  "python3.13t" 또는 "python3.13t.exe"라는
별도의 실행 파일이 필요합니다. *free-threaded*로 표시된 미리 빌드된 바
이너리는 공식 Windows 및 macOS 설치 프로그램의 일부로 설치할 수 있으며
, 또는 "--disable-gil" 옵션을 사용하여 소스 코드로부터 CPython을 빌드
할 수 있습니다.

제한 없는 스레드 실행은 사용 가능한 CPU 코어에서 스레드를 병렬로 실행
하여 가용 처리 능력을 온전히 활용할 수 있게 합니다. 모든 소프트웨어가
자동적으로 이를 통해 이점을 갖게 되는 것은 아니지만, 스레딩을 염두에
두고 설계된 프로그램은 다중 코어 하드웨어에서 보다 더 빠르게 실행됩니
다. **제한 없는 스레드 모드는 실험적**이며 개선 작업이 진행 중이므로,
버그가 있을 수 있으며, 단일 스레드를 통한 실행의 성능이 저하될 수 있습
니다. 제한 없는 스레드를 사용하는 파이썬(CPython) 빌드는 실행 시 환경
변수 "PYTHON_GIL" 또는 명령줄 옵션 "-X gil=1"을 사용해 GIL을 활성화하
여 선택적으로 실행할 수 있습니다.

사용 중인 인터프리터가 제한 없는 스레드의 사용을 지원하는지 확인하려면
"python -VV" 및 "sys.version"에서 "experimental free-threading build"
를 통해 확인할 수 있습니다. 새 "sys._is_gil_enabled()" 함수를 사용하면
실행 중인 프로세스에서 GIL이 실제로 비활성화되어 있는지 확인할 수 있습
니다.

C-API 확장 모듈은 제한 없는 스레드(free-threaded)를 사용하는 빌드용으
로 따로 빌드해야 합니다. 전역 인터프리터 잠금(Global Interpreter Lock;
*GIL*) 비활성 실행을 지원하는 확장 모듈은 "Py_mod_gil" 슬롯을 사용해야
합니다. 개별 단계 초기화(single-phase init)를 사용하는 확장 모듈은 GIL
비활성 실행 지원 여부를 표시하기 위해 "PyUnstable_Module_SetGIL()"을
사용해야 합니다. 이러한 메커니즘을 사용하지 않는 C 확장을 임포트하면
GIL이 자동으로 활성화됩니다. "PYTHON_GIL" 환경 변수나 "-X gil=0" 옵션
으로 GIL을 명시적으로 비활성화한 경우는 예외입니다. 제한 없는 스레드를
사용하는 빌드에서 C 확장이 포함된 패키지를 설치하려면 pip 24.1 이상이
필요합니다.

이러한 개선 작업은 많은 개인과 조직, 그리고 제한 없는 스레드(free-
threading) 사용 지원을 테스트하고 활성화하는 데 기여한 파이썬 및 다양
한 제삼자(third-parth) 프로젝트 커뮤니티들 덕분이었습니다. 주목할 만한
기여자로는 Sam Gross, Ken Jin, Donghee Na, Itamar Oren, Matt Page,
Brett Simmers, Dino Viehland, Carl Meyer, Nathan Goldbaum, Ralf
Gommers, Lysandros Nikolaou 등이 있으며, 이외에도 많은 분들이 있습니다
. 이 기여자들 중 많은 분들이 Meta에 재직하고 있으며, Meta는 이 프로젝
트를 지원하기 위해 상당한 엔지니어링 자원을 제공하였습니다.

더 보기:

  이러한 개선 작업의 배경과 근거에 대한 보다 구체적인 정보를 위해서는
  **PEP 703** "Making the Global Interpreter Lock Optional in CPython"
  를 열람 부탁드립니다.

  제한 없는 스레드 사용을 지원하기 위한 확장 모듈 이식: 커뮤니티에 의
  해 지원되는 제한 없는 스레드 사용 지원에 대한 이식 가이드로, 확장 모
  듈 작성자를 위한 가이드입니다.


실험적인 지정 시간 구동 (Just-In-Time; JIT) 컴파일러
----------------------------------------------------

"--enable-experimental-jit" 옵션을 사용하여 CPython을 구성하고 빌드하
면 일부 파이썬 프로그램의 속도를 높일 수 있는 JIT 컴파일러가 추가됩니
다. 윈도우에서 JIT를 활성화하려면 "PCbuild/build.bat --experimental-
jit"을 사용하고, 2단계 (Tier 2) 인터프리터를 활성화하려면 "--
experimental-jit-interpreter"를 사용하세요. 빌드 요구 사항과 추가 지원
정보는 "Tools/jit/README.md"를 확인 부탁드립니다.

"--enable-experimental-jit" 옵션은 다음과 같은 특정 값들을 받을 수 있
습니다. 특정 값을 지정하지 않으면 기본값은 "yes"입니다.

* "no": 2단계 (Tier 2) 인터프리터 및 JIT 파이프라인을 모두 비활성화합
  니다.

* "yes": JIT (Just-In-Time; 지정 시간 구동) 컴파일러를 활성화합니다.
  런타임에 JIT를 비활성화하려면 환경 변수 "PYTHON_JIT=0"을 설정할 수
  있습니다.

* "yes-off": JIT를 빌드하되 기본값으로 비활성화합니다. 런타임에 JIT를
  활성화하려면 환경 변수 "PYTHON_JIT=1"을 설정할 수 있습니다.

* "interpreter": 2단계 (Tier 2) 인터프리터를 활성화하지만 JIT는 비활성
  화합니다. 이 인터프리터는 환경 변수 "PYTHON_JIT=0"을 설정하여 비활성
  화할 수 있습니다.

내부 아키텍처는 대략적으로 다음과 같습니다:

* 시작 지점은 최적화된 *1단계(Tier 1) 바이트 코드*입니다. 관련된 보다
  구체적인 정보를 위해서는 3.11 버전의 새로운 기능를 열람 부탁드립니다
  .

* *1단계(Tier 1) 바이트 코드*가 빈번하게 실행되는 경우, 완전히 내부용
  인 새로운 중간 표현(IR)인 *2단계 IR(Tier 2 IR)*로 변환됩니다. 변환된
  이러한 중간 표현은 마이크로 연산(uops)으로 명명되기도 합니다.

* 2단계 IR도 1단계와 같은 스택 기반 가상 머신을 사용하지만, 명령어 형
  식의 경우 기계어로 변환하기에 보다 더 적합합니다.

* 2단계 IR에는 여러개의 최적화 패스가 있으며, 이는 인터프리터에 의해
  처리되어 실행되거나 기계어로 변환되기 전에 적용됩니다.

* 2단계(Tier 2) 인터프리터가 있지만, 주로 앞서 서술한 최적화 파이프라
  인의 초기 단계를 디버깅하기 위해 만들어진 것입니다. 2단계 인터프리터
  는 파이썬에서 "--enable-experimental-jit=interpreter" 옵션을 설정함
  을 통해 활성화할 수 있습니다.

* 지정 시간 구동 (JIT; Just-In-Time) 컴파일러가 활성화되면, 최적화된 2
  단계(Tier 2) IR이 기계어로 변환되어 실행됩니다.

* 기계어 변환 과정에서는 *복사-후-패치 (copy-and-patch)*라는 기법을 사
  용합니다. 런타임 의존성은 없지만, 빌드의 경우 LLVM에 대한 새로운 의
  존성이 추가되었습니다.

더 보기: **PEP 744**

(JIT은 Brandt Bucher에 의해, Haoran Xu와 Fredrik Kjolstad의 논문에 영
감을 받아 개발되었습니다. 2단계 IR의 경우 Mark Shannon과 Guido van
Rossum에 의해 개발되었습니다. 2단계 IR의 최적화의 경우 Ken Jin에 의해
개발되었습니다.)


"locals()"의 변형에 대한 의미 구조 정의
---------------------------------------

지금까지 "locals()"의 반환값을 변경했을 때에 예상되는 결과는 개별적인
파이썬 구현에 맡겨져 있었습니다. Python 3.13부터는 **PEP 667**이 대부
분의 코드 실행 스코프에 대해 CPython의 기존 동작을 표준화하고, *최적화
된 스코프*(함수, 제너레이터, 코루틴, 컴프리헨션, 제너레이터 표현식)에
서는 현재 할당되어 있는 지역 변수들에 대한 서로 독립적인 스냅샷으로 명
시적으로 반환하도록 변경합니다. 이는 지역적으로 참조된 비지역 변수들이
종료 시점에서 확인되는 경우을 포함합니다.

앞서 서술한 것과 같이 최적화된 스코프에서 "locals()"의 의미 구조가 바
뀌면서, 명시적인 네임 스페이스를 제공하지 않는 경우, 암시적으로
"locals()"을 대상으로 실행되는 코드 실행 함수들(예: "exec()",
"eval()")의 기본 동작도 영향을 받았습니다. 이전 버전에서는 코드 실행
함수를 호출한 뒤 "locals()"을 호출하여 변경 사항에 액세스할 수 있는지
가 구체적인 개별 구현에 따라 달라졌었습니다. 구체적으로, CPython에서
대부분의 경우 이러한 방식은 무리 없이 잘 동작하였지만, 종종 같은 스코
프의 공유 스냅샷이 다른 코드(디버거나 코드 실행 추적 도구 등)에 의해
재설정될 수 있기 때문에 최적화된 스코프에서 실패하는 경우도 있었습니다
. Python 3.13에서는 해당 코드를 항상 최적화된 스코프의 지역 변수에 대
한 독립적인 스냅샷에 대해서만 실행하므로, 그 변경 사항은 이후의
"locals()" 호출에서 절대로 보이지 않습니다. 이러한 경우들에서 변경 내
용을 확인하기 위해서는 관련 함수에 명시적인 네임 스페이스를 전달해야
합니다. 또는 디스크에서 파이썬 파일을 실행할 때처럼 실행 결과의 네임
스페이스를 반환하는 상위 수준의 코드 실행 API(예를 들어,
"runpy.run_path()")로 코드를 변경하는 것이 보다 바람직할 수 있습니다.

디버거와 유사 도구들이 (앞서 서술한 변화의 영향을 받는 스코프에서) 지
역 변수를 안정적으로 업데이트할 수 있도록, "FrameType.f_locals"는 해당
스코프의 지역 변수와 그 스코프에서 참조되는 비지역 변수에 대한 이어쓰
기(write-through) 프록시를 반환합니다. 런타임 의미가 불분명하고 일관성
없이 업데이트되던 (공유된) "dict" 인스턴스를 반환하지 않습니다.

관련된 C API 변경 사항과 사용 지원 중단 등에 대한 보다 구체적인 정보를
위해서는 **PEP 667**을 열람 부탁드립니다. 또한 관련된 (코드) 이식에 대
한 가이드의 경우 Python API 및 C API을 열람 부탁드립니다.

(Mark Shannon과 Tian Gao가 PEP을 작성하였고 gh-74929를 통해 기능을 구
현하였습니다. Guido van Rossum과 Alyssa Coghlan이 설명서를 최신화하였
습니다.)


모바일 플랫폼들에 대한 지원
---------------------------

**PEP 730**: iOS가 **PEP 11**에서 지원하는 플랫폼으로, "arm64-apple-
ios" (2013년 이후 출시된 iPhone 및 iPad 기기)와 "arm64-apple-ios-
simulator" (Apple 실리콘 하드웨어에서 실행되는 Xcode iOS 시뮬레이터)는
3단계 (Tier 3)로 지정되었습니다. "x86_64-apple-ios-simulator" (구형
"x86_64" 하드웨어에서 실행되는 Xcode iOS 시뮬레이터)는 3단계 지원 플랫
폼은 아니지만, 최선의 노력(best-effort)으로 지원됩니다. (Russell
Keith-Magee PEP을 작성하였고 gh-114099를 통해 기능을 구현하였습니다.)

**PEP 738**: Android가 **PEP 11**에서 지원하는 플랫폼으로, "aarch64
-linux-android"와 "x86_64-linux-android"은 3단계 (Tier 3)로 지정되었습
니다. 32비트 "arm-linux-androideabi"와 "i686-linux-android"는 3단계 지
원 플랫폼은 아니지만, 최선의 노력(best-effort)으로 지원됩니다.
(Malcolm Smith가 PEP을 작성하였고 gh-116622을 통해 기능을 구현하였습니
다.)

더 보기: **PEP 730**, **PEP 738**


Other Language Changes
======================

* The compiler now strips common leading whitespace from every line in
  a docstring. This reduces the size of the *bytecode cache* (such as
  ".pyc" files), with reductions in file size of around 5%, for
  example in "sqlalchemy.orm.session" from SQLAlchemy 2.0. This change
  affects tools that use docstrings, such as "doctest".

     >>> def spam():
     ...     """
     ...         This is a docstring with
     ...           leading whitespace.
     ...
     ...         It even has multiple paragraphs!
     ...     """
     ...
     >>> spam.__doc__
     '\nThis is a docstring with\n  leading whitespace.\n\nIt even has multiple paragraphs!\n'

  (Contributed by Inada Naoki in gh-81283.)

* Annotation scopes within class scopes can now contain lambdas and
  comprehensions. Comprehensions that are located within class scopes
  are not inlined into their parent scope.

     class C[T]:
         type Alias = lambda: T

  (Contributed by Jelle Zijlstra in gh-109118 and gh-118160.)

* Future statements are no longer triggered by relative imports of the
  "__future__" module, meaning that statements of the form "from
  .__future__ import ..." are now simply standard relative imports,
  with no special features activated. (Contributed by Jeremiah Gabriel
  Pascual in gh-118216.)

* "global" declarations are now permitted in "except" blocks when that
  global is used in the "else" block. Previously this raised an
  erroneous "SyntaxError". (Contributed by Irit Katriel in gh-111123.)

* Add "PYTHON_FROZEN_MODULES", a new environment variable that
  determines whether frozen modules are ignored by the import
  machinery, equivalent to the "-X frozen_modules" command-line
  option. (Contributed by Yilei Yang in gh-111374.)

* Add support for the perf profiler working without frame pointers
  through the new environment variable "PYTHON_PERF_JIT_SUPPORT" and
  command-line option "-X perf_jit". (Contributed by Pablo Galindo in
  gh-118518.)

* The location of a ".python_history" file can be changed via the new
  "PYTHON_HISTORY" environment variable. (Contributed by Levi Sabah,
  Zackery Spytz and Hugo van Kemenade in gh-73965.)

* Classes have a new "__static_attributes__" attribute. This is
  populated by the compiler with a tuple of the class's attribute
  names which are assigned through "self.<name>" from any function in
  its body. (Contributed by Irit Katriel in gh-115775.)

* The compiler now creates a "__firstlineno__" attribute on classes
  with the line number of the first line of the class definition.
  (Contributed by Serhiy Storchaka in gh-118465.)

* The "exec()" and "eval()" builtins now accept the *globals* and
  *locals* arguments as keywords. (Contributed by Raphael Gaschignard
  in gh-105879)

* The "compile()" builtin now accepts a new flag,
  "ast.PyCF_OPTIMIZED_AST", which is similar to "ast.PyCF_ONLY_AST"
  except that the returned AST is optimized according to the value of
  the *optimize* argument. (Contributed by Irit Katriel in gh-108113).

* Add a "__name__" attribute on "property" objects. (Contributed by
  Eugene Toder in gh-101860.)

* Add "PythonFinalizationError", a new exception derived from
  "RuntimeError" and used to signal when operations are blocked during
  *finalization*. The following callables now raise
  "PythonFinalizationError", instead of "RuntimeError":

  * "_thread.start_new_thread()"

  * "os.fork()"

  * "os.forkpty()"

  * "subprocess.Popen"

  (Contributed by Victor Stinner in gh-114570.)

* Allow the *count* argument of "str.replace()" to be a keyword.
  (Contributed by Hugo van Kemenade in gh-106487.)

* Many functions now emit a warning if a boolean value is passed as a
  file descriptor argument. This can help catch some errors earlier.
  (Contributed by Serhiy Storchaka in gh-82626.)

* Added "name" and "mode" attributes for compressed and archived file-
  like objects in the "bz2", "lzma", "tarfile", and "zipfile" modules.
  (Contributed by Serhiy Storchaka in gh-115961.)


New Modules
===========

* "dbm.sqlite3": An SQLite backend for "dbm". (Contributed by Raymond
  Hettinger and Erlend E. Aasland in gh-100414.)


Improved Modules
================


argparse
--------

* Add the *deprecated* parameter to the "add_argument()" and
  "add_parser()" methods, to enable deprecating command-line options,
  positional arguments, and subcommands. (Contributed by Serhiy
  Storchaka in gh-83648.)


array
-----

* Add the "'w'" type code ("Py_UCS4") for Unicode characters. It
  should be used instead of the deprecated "'u'" type code.
  (Contributed by Inada Naoki in gh-80480.)

* Register "array.array" as a "MutableSequence" by implementing the
  "clear()" method. (Contributed by Mike Zimin in gh-114894.)


ast
---

* The constructors of node types in the "ast" module are now stricter
  in the arguments they accept, with more intuitive behavior when
  arguments are omitted.

  If an optional field on an AST node is not included as an argument
  when constructing an instance, the field will now be set to "None".
  Similarly, if a list field is omitted, that field will now be set to
  an empty list, and if an "expr_context" field is omitted, it
  defaults to "Load()". (Previously, in all cases, the attribute would
  be missing on the newly constructed AST node instance.)

  In all other cases, where a required argument is omitted, the node
  constructor will emit a "DeprecationWarning". This will raise an
  exception in Python 3.15. Similarly, passing a keyword argument to
  the constructor that does not map to a field on the AST node is now
  deprecated, and will raise an exception in Python 3.15.

  These changes do not apply to user-defined subclasses of "ast.AST"
  unless the class opts in to the new behavior by defining the
  "AST._field_types" mapping.

  (Contributed by Jelle Zijlstra in gh-105858, gh-117486, and
  gh-118851.)

* "ast.parse()" now accepts an optional argument *optimize* which is
  passed on to "compile()". This makes it possible to obtain an
  optimized AST. (Contributed by Irit Katriel in gh-108113.)


asyncio
-------

* "asyncio.as_completed()" now returns an object that is both an
  *asynchronous iterator* and a plain *iterator* of *awaitables*. The
  awaitables yielded by asynchronous iteration include original task
  or future objects that were passed in, making it easier to associate
  results with the tasks being completed. (Contributed by Justin
  Arthur in gh-77714.)

* "asyncio.loop.create_unix_server()" will now automatically remove
  the Unix socket when the server is closed. (Contributed by Pierre
  Ossman in gh-111246.)

* "DatagramTransport.sendto()" will now send zero-length datagrams if
  called with an empty bytes object. The transport flow control also
  now accounts for the datagram header when calculating the buffer
  size. (Contributed by Jamie Phan in gh-115199.)

* Add "Queue.shutdown" and "QueueShutDown" to manage queue
  termination. (Contributed by Laurie Opperman and Yves Duprat in
  gh-104228.)

* Add the "Server.close_clients()" and "Server.abort_clients()"
  methods, which more forcefully close an asyncio server. (Contributed
  by Pierre Ossman in gh-113538.)

* Accept a tuple of separators in "StreamReader.readuntil()", stopping
  when any one of them is encountered. (Contributed by Bruce Merry in
  gh-81322.)

* Improve the behavior of "TaskGroup" when an external cancellation
  collides with an internal cancellation. For example, when two task
  groups are nested and both experience an exception in a child task
  simultaneously, it was possible that the outer task group would
  hang, because its internal cancellation was swallowed by the inner
  task group.

  In the case where a task group is cancelled externally and also must
  raise an "ExceptionGroup", it will now call the parent task's
  "cancel()" method. This ensures that a "CancelledError" will be
  raised at the next "await", so the cancellation is not lost.

  An added benefit of these changes is that task groups now preserve
  the cancellation count ("cancelling()").

  In order to handle some corner cases, "uncancel()" may now reset the
  undocumented "_must_cancel" flag when the cancellation count reaches
  zero.

  (Inspired by an issue reported by Arthur Tacca in gh-116720.)

* When "TaskGroup.create_task()" is called on an inactive "TaskGroup",
  the given coroutine will be closed (which prevents a
  "RuntimeWarning" about the given coroutine being never awaited).
  (Contributed by Arthur Tacca and Jason Zhang in gh-115957.)

* The function and methods named "create_task" have received a new
  "**kwargs" argument that is passed through to the task constructor.
  This change was accidentally added in 3.13.3, and broke the API
  contract for custom task factories. Several third-party task
  factories implemented workarounds for this. In 3.13.4 and later
  releases the old factory contract is honored once again (until
  3.14). To keep the workarounds working, the extra "**kwargs"
  argument still allows passing additional keyword arguments to "Task"
  and to custom task factories.

  This affects the following function and methods:
  "asyncio.create_task()", "asyncio.loop.create_task()",
  "asyncio.TaskGroup.create_task()". (Contributed by Thomas Grainger
  in gh-128307.)


base64
------

* Add "z85encode()" and "z85decode()" functions for encoding "bytes"
  as Z85 data and decoding Z85-encoded data to "bytes". (Contributed
  by Matan Perelman in gh-75299.)


compileall
----------

* The default number of worker threads and processes is now selected
  using "os.process_cpu_count()" instead of "os.cpu_count()".
  (Contributed by Victor Stinner in gh-109649.)


concurrent.futures
------------------

* The default number of worker threads and processes is now selected
  using "os.process_cpu_count()" instead of "os.cpu_count()".
  (Contributed by Victor Stinner in gh-109649.)


configparser
------------

* "ConfigParser" now has support for unnamed sections, which allows
  for top-level key-value pairs. This can be enabled with the new
  *allow_unnamed_section* parameter. (Contributed by Pedro Sousa
  Lacerda in gh-66449.)


copy
----

* The new "replace()" function and the "replace protocol" make
  creating modified copies of objects much simpler. This is especially
  useful when working with immutable objects. The following types
  support the "replace()" function and implement the replace protocol:

  * "collections.namedtuple()"

  * "dataclasses.dataclass"

  * "datetime.datetime", "datetime.date", "datetime.time"

  * "inspect.Signature", "inspect.Parameter"

  * "types.SimpleNamespace"

  * code objects

  Any user-defined class can also support "copy.replace()" by defining
  the "__replace__()" method. (Contributed by Serhiy Storchaka in
  gh-108751.)


ctypes
------

* As a consequence of necessary internal refactoring, initialization
  of internal metaclasses now happens in "__init__" rather than in
  "__new__". This affects projects that subclass these internal
  metaclasses to provide custom initialization. Generally:

  * Custom logic that was done in "__new__" after calling
    "super().__new__" should be moved to "__init__".

  * To create a class, call the metaclass, not only the metaclass's
    "__new__" method.

  See gh-124520 for discussion and links to changes in some affected
  projects.

* "ctypes.Structure" objects have a new "_align_" attribute which
  allows the alignment of the structure being packed to/from memory to
  be specified explicitly. (Contributed by Matt Sanderson in
  gh-112433)


dbm
---

* Add "dbm.sqlite3", a new module which implements an SQLite backend,
  and make it the default "dbm" backend. (Contributed by Raymond
  Hettinger and Erlend E. Aasland in gh-100414.)

* Allow removing all items from the database through the new "clear()"
  methods of the GDBM and NDBM database objects. (Contributed by
  Donghee Na in gh-107122.)


dis
---

* Change the output of "dis" module functions to show logical labels
  for jump targets and exception handlers, rather than offsets. The
  offsets can be added with the new "-O" command-line option or the
  *show_offsets* argument. (Contributed by Irit Katriel in gh-112137.)

* "get_instructions()" no longer represents cache entries as separate
  instructions. Instead, it returns them as part of the "Instruction",
  in the new *cache_info* field. The *show_caches* argument to
  "get_instructions()" is deprecated and no longer has any effect.
  (Contributed by Irit Katriel in gh-112962.)


doctest
-------

* "doctest" output is now colored by default. This can be controlled
  via the new "PYTHON_COLORS" environment variable as well as the
  canonical "NO_COLOR" and "FORCE_COLOR" environment variables. See
  also Controlling color. (Contributed by Hugo van Kemenade in
  gh-117225.)

* The "DocTestRunner.run()" method now counts the number of skipped
  tests. Add the "DocTestRunner.skips" and "TestResults.skipped"
  attributes. (Contributed by Victor Stinner in gh-108794.)


email
-----

* Headers with embedded newlines are now quoted on output. The
  "generator" will now refuse to serialize (write) headers that are
  improperly folded or delimited, such that they would be parsed as
  multiple headers or joined with adjacent data. If you need to turn
  this safety feature off, set "verify_generated_headers".
  (Contributed by Bas Bloemsaat and Petr Viktorin in gh-121650.)

* "getaddresses()" and "parseaddr()" now return "('', '')" pairs in
  more situations where invalid email addresses are encountered
  instead of potentially inaccurate values. The two functions have a
  new optional *strict* parameter (default "True"). To get the old
  behavior (accepting malformed input), use "strict=False".
  "getattr(email.utils, 'supports_strict_parsing', False)" can be used
  to check if the *strict* parameter is available. (Contributed by
  Thomas Dwyer and Victor Stinner for gh-102988 to improve the **CVE
  2023-27043** fix.)


enum
----

* "EnumDict" has been made public to better support subclassing
  "EnumType".


fractions
---------

* "Fraction" objects now support the standard format specification
  mini-language rules for fill, alignment, sign handling, minimum
  width, and grouping. (Contributed by Mark Dickinson in gh-111320.)


glob
----

* Add "translate()", a function to convert a path specification with
  shell-style wildcards to a regular expression. (Contributed by
  Barney Gale in gh-72904.)


importlib
---------

* The following functions in "importlib.resources" now allow accessing
  a directory (or tree) of resources, using multiple positional
  arguments (the *encoding* and *errors* arguments in the text-reading
  functions are now keyword-only):

  * "is_resource()"

  * "open_binary()"

  * "open_text()"

  * "path()"

  * "read_binary()"

  * "read_text()"

  These functions are no longer deprecated and are not scheduled for
  removal. (Contributed by Petr Viktorin in gh-116608.)

* "contents()" remains deprecated in favor of the fully-featured
  "Traversable" API. However, there is now no plan to remove it.
  (Contributed by Petr Viktorin in gh-116608.)


io
--

* The "IOBase" finalizer now logs any errors raised by the "close()"
  method with "sys.unraisablehook". Previously, errors were ignored
  silently by default, and only logged in Python Development Mode or
  when using a Python debug build. (Contributed by Victor Stinner in
  gh-62948.)


ipaddress
---------

* Add the "IPv4Address.ipv6_mapped" property, which returns the
  IPv4-mapped IPv6 address. (Contributed by Charles Machalow in
  gh-109466.)

* Fix "is_global" and "is_private" behavior in "IPv4Address",
  "IPv6Address", "IPv4Network", and "IPv6Network". (Contributed by
  Jakub Stasiak in gh-113171.)


itertools
---------

* "batched()" has a new *strict* parameter, which raises a
  "ValueError" if the final batch is shorter than the specified batch
  size. (Contributed by Raymond Hettinger in gh-113202.)


marshal
-------

* Add the *allow_code* parameter in module functions. Passing
  "allow_code=False" prevents serialization and de-serialization of
  code objects which are incompatible between Python versions.
  (Contributed by Serhiy Storchaka in gh-113626.)


math
----

* The new function "fma()" performs fused multiply-add operations.
  This computes "x * y + z" with only a single round, and so avoids
  any intermediate loss of precision. It wraps the "fma()" function
  provided by C99, and follows the specification of the IEEE 754
  "fusedMultiplyAdd" operation for special cases. (Contributed by Mark
  Dickinson and Victor Stinner in gh-73468.)


mimetypes
---------

* Add the "guess_file_type()" function to guess a MIME type from a
  filesystem path. Using paths with "guess_type()" is now *soft
  deprecated*. (Contributed by Serhiy Storchaka in gh-66543.)


mmap
----

* "mmap" is now protected from crashing on Windows when the mapped
  memory is inaccessible due to file system errors or access
  violations. (Contributed by Jannis Weigend in gh-118209.)

* "mmap" has a new "seekable()" method that can be used when a
  seekable file-like object is required. The "seek()" method now
  returns the new absolute position. (Contributed by Donghee Na and
  Sylvie Liberman in gh-111835.)

* The new UNIX-only *trackfd* parameter for "mmap" controls file
  descriptor duplication; if false, the file descriptor specified by
  *fileno* will not be duplicated. (Contributed by Zackery Spytz and
  Petr Viktorin in gh-78502.)


multiprocessing
---------------

* The default number of worker threads and processes is now selected
  using "os.process_cpu_count()" instead of "os.cpu_count()".
  (Contributed by Victor Stinner in gh-109649.)


os
--

* Add "process_cpu_count()" function to get the number of logical CPU
  cores usable by the calling thread of the current process.
  (Contributed by Victor Stinner in gh-109649.)

* "cpu_count()" and "process_cpu_count()" can be overridden through
  the new environment variable "PYTHON_CPU_COUNT" or the new command-
  line option "-X cpu_count". This option is useful for users who need
  to limit CPU resources of a container system without having to
  modify application code or the container itself. (Contributed by
  Donghee Na in gh-109595.)

* Add a low level interface to Linux's *timer file descriptors* via
  "timerfd_create()", "timerfd_settime()", "timerfd_settime_ns()",
  "timerfd_gettime()", "timerfd_gettime_ns()", "TFD_NONBLOCK",
  "TFD_CLOEXEC", "TFD_TIMER_ABSTIME", and "TFD_TIMER_CANCEL_ON_SET"
  (Contributed by Masaru Tsuchiyama in gh-108277.)

* "lchmod()" and the *follow_symlinks* argument of "chmod()" are both
  now available on Windows. Note that the default value of
  *follow_symlinks* in "lchmod()" is "False" on Windows. (Contributed
  by Serhiy Storchaka in gh-59616.)

* "fchmod()" and support for file descriptors in "chmod()" are both
  now available on Windows. (Contributed by Serhiy Storchaka in
  gh-113191.)

* On Windows, "mkdir()" and "makedirs()" 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.)

* "posix_spawn()" now accepts "None" for the *env* argument, which
  makes the newly spawned process use the current process environment.
  (Contributed by Jakub Kulik in gh-113119.)

* "posix_spawn()" can now use the "POSIX_SPAWN_CLOSEFROM" attribute in
  the *file_actions* parameter on platforms that support
  "posix_spawn_file_actions_addclosefrom_np()". (Contributed by Jakub
  Kulik in gh-113117.)


os.path
-------

* Add "isreserved()" to check if a path is reserved on the current
  system. This function is only available on Windows. (Contributed by
  Barney Gale in gh-88569.)

* On Windows, "isabs()" no longer considers paths starting with
  exactly one slash ("\" or "/") to be absolute. (Contributed by
  Barney Gale and Jon Foster in gh-44626.)

* "realpath()" now resolves MS-DOS style file names even if the file
  is not accessible. (Contributed by Moonsik Park in gh-82367.)


pathlib
-------

* Add "UnsupportedOperation", which is raised instead of
  "NotImplementedError" when a path operation isn't supported.
  (Contributed by Barney Gale in gh-89812.)

* Add a new constructor for creating "Path" objects from 'file' URIs
  ("file:///"), "Path.from_uri()". (Contributed by Barney Gale in
  gh-107465.)

* Add "PurePath.full_match()" for matching paths with shell-style
  wildcards, including the recursive wildcard ""**"". (Contributed by
  Barney Gale in gh-73435.)

* Add the "PurePath.parser" class attribute to store the
  implementation of "os.path" used for low-level path parsing and
  joining. This will be either "posixpath" or "ntpath".

* Add *recurse_symlinks* keyword-only argument to "Path.glob()" and
  "rglob()". (Contributed by Barney Gale in gh-77609.)

* "Path.glob()" and "rglob()" now return files and directories when
  given a pattern that ends with ""**"". Previously, only directories
  were returned. (Contributed by Barney Gale in gh-70303.)

* Add the *follow_symlinks* keyword-only argument to "Path.is_file",
  "Path.is_dir", "Path.owner()", and "Path.group()". (Contributed by
  Barney Gale in gh-105793 and Kamil Turek in gh-107962.)


pdb
---

* "breakpoint()" and "set_trace()" now enter the debugger immediately
  rather than on the next line of code to be executed. This change
  prevents the debugger from breaking outside of the context when
  "breakpoint()" is positioned at the end of the context. (Contributed
  by Tian Gao in gh-118579.)

* "sys.path[0]" is no longer replaced by the directory of the script
  being debugged when "sys.flags.safe_path" is set. (Contributed by
  Tian Gao and Christian Walther in gh-111762.)

* "zipapp" is now supported as a debugging target. (Contributed by
  Tian Gao in gh-118501.)

* Add ability to move between chained exceptions during post-mortem
  debugging in "pm()" using the new "exceptions [exc_number]" command
  for Pdb. (Contributed by Matthias Bussonnier in gh-106676.)

* Expressions and statements whose prefix is a pdb command are now
  correctly identified and executed. (Contributed by Tian Gao in
  gh-108464.)


queue
-----

* Add "Queue.shutdown" and "ShutDown" to manage queue termination.
  (Contributed by Laurie Opperman and Yves Duprat in gh-104750.)


random
------

* Add a command-line interface. (Contributed by Hugo van Kemenade in
  gh-118131.)


re
--

* Rename "re.error" to "PatternError" for improved clarity. "re.error"
  is kept for backward compatibility.


shutil
------

* Support the *dir_fd* and *follow_symlinks* keyword arguments in
  "chown()". (Contributed by Berker Peksag and Tahia K in gh-62308)


site
----

* ".pth" files are now decoded using UTF-8 first, and then with the
  *locale encoding* if UTF-8 decoding fails. (Contributed by Inada
  Naoki in gh-117802.)


sqlite3
-------

* A "ResourceWarning" is now emitted if a "Connection" object is not
  "closed" explicitly. (Contributed by Erlend E. Aasland in
  gh-105539.)

* Add the *filter* keyword-only parameter to "Connection.iterdump()"
  for filtering database objects to dump. (Contributed by Mariusz
  Felisiak in gh-91602.)


ssl
---

* The "create_default_context()" API now includes
  "VERIFY_X509_PARTIAL_CHAIN" and "VERIFY_X509_STRICT" in its default
  flags.

  참고:

    "VERIFY_X509_STRICT" may reject pre-**RFC 5280** or malformed
    certificates that the underlying OpenSSL implementation might
    otherwise accept. Whilst disabling this is not recommended, you
    can do so using:

       import ssl

       ctx = ssl.create_default_context()
       ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT

  (Contributed by William Woodruff in gh-112389.)


statistics
----------

* Add "kde()" for kernel density estimation. This makes it possible to
  estimate a continuous probability density function from a fixed
  number of discrete samples. (Contributed by Raymond Hettinger in
  gh-115863.)

* Add "kde_random()" for sampling from an estimated probability
  density function created by "kde()". (Contributed by Raymond
  Hettinger in gh-115863.)


subprocess
----------

* The "subprocess" module now uses the "posix_spawn()" function in
  more situations.

  Notably, when *close_fds* is "True" (the default), "posix_spawn()"
  will be used when the C library provides
  "posix_spawn_file_actions_addclosefrom_np()", which includes recent
  versions of Linux, FreeBSD, and Solaris. On Linux, this should
  perform similarly to the existing Linux "vfork()" based code.

  A private control knob "subprocess._USE_POSIX_SPAWN" can be set to
  "False" if you need to force "subprocess" to never use
  "posix_spawn()". Please report your reason and platform details in
  the issue tracker if you set this so that we can improve our API
  selection logic for everyone. (Contributed by Jakub Kulik in
  gh-113117.)


sys
---

* Add the "_is_interned()" function to test if a string was interned.
  This function is not guaranteed to exist in all implementations of
  Python. (Contributed by Serhiy Storchaka in gh-78573.)


tempfile
--------

* 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**.
  (Contributed by Steve Dower in gh-118486.)


time
----

* On Windows, "monotonic()" now uses the "QueryPerformanceCounter()"
  clock for a resolution of 1 microsecond, instead of the
  "GetTickCount64()" clock which has a resolution of 15.6
  milliseconds. (Contributed by Victor Stinner in gh-88494.)

* On Windows, "time()" now uses the "GetSystemTimePreciseAsFileTime()"
  clock for a resolution of 1 microsecond, instead of the
  "GetSystemTimeAsFileTime()" clock which has a resolution of 15.6
  milliseconds. (Contributed by Victor Stinner in gh-63207.)


tkinter
-------

* Add "tkinter" widget methods: "tk_busy_hold()",
  "tk_busy_configure()", "tk_busy_cget()", "tk_busy_forget()",
  "tk_busy_current()", and "tk_busy_status()". (Contributed by Miguel,
  klappnase and Serhiy Storchaka in gh-72684.)

* The "tkinter" widget method "wm_attributes()" now accepts the
  attribute name without the minus prefix to get window attributes,
  for example "w.wm_attributes('alpha')" and allows specifying
  attributes and values to set as keyword arguments, for example
  "w.wm_attributes(alpha=0.5)". (Contributed by Serhiy Storchaka in
  gh-43457.)

* "wm_attributes()" can now return attributes as a "dict", by using
  the new optional keyword-only parameter *return_python_dict*.
  (Contributed by Serhiy Storchaka in gh-43457.)

* "Text.count()" can now return a simple "int" when the new optional
  keyword-only parameter *return_ints* is used. Otherwise, the single
  count is returned as a 1-tuple or "None". (Contributed by Serhiy
  Storchaka in gh-97928.)

* Support the "vsapi" element type in the "element_create()" method of
  "tkinter.ttk.Style". (Contributed by Serhiy Storchaka in gh-68166.)

* Add the "after_info()" method for Tkinter widgets. (Contributed by
  Cheryl Sabella in gh-77020.)

* Add a new "copy_replace()" method to "PhotoImage" to copy a region
  from one image to another, possibly with pixel zooming, subsampling,
  or both. (Contributed by Serhiy Storchaka in gh-118225.)

* Add *from_coords* parameter to the "PhotoImage" methods "copy()",
  "zoom()" and "subsample()". Add *zoom* and *subsample* parameters to
  the "PhotoImage" method "copy()". (Contributed by Serhiy Storchaka
  in gh-118225.)

* Add the "PhotoImage" methods "read()" to read an image from a file
  and "data()" to get the image data. Add *background* and *grayscale*
  parameters to the "write()" method. (Contributed by Serhiy Storchaka
  in gh-118271.)


traceback
---------

* Add the "exc_type_str" attribute to "TracebackException", which
  holds a string display of the *exc_type*. Deprecate the "exc_type"
  attribute, which holds the type object itself. Add parameter
  *save_exc_type* (default "True") to indicate whether "exc_type"
  should be saved. (Contributed by Irit Katriel in gh-112332.)

* Add a new *show_group* keyword-only parameter to
  "TracebackException.format_exception_only()" to (recursively) format
  the nested exceptions of a "BaseExceptionGroup" instance.
  (Contributed by Irit Katriel in gh-105292.)


types
-----

* "SimpleNamespace" can now take a single positional argument to
  initialise the namespace's arguments. This argument must either be a
  mapping or an iterable of key-value pairs. (Contributed by Serhiy
  Storchaka in gh-108191.)


typing
------

* **PEP 705**: Add "ReadOnly", a special typing construct to mark a
  "TypedDict" item as read-only for type checkers.

* **PEP 742**: Add "TypeIs", a typing construct that can be used to
  instruct a type checker how to narrow a type.

* Add "NoDefault", a sentinel object used to represent the defaults of
  some parameters in the "typing" module. (Contributed by Jelle
  Zijlstra in gh-116126.)

* Add "get_protocol_members()" to return the set of members defining a
  "typing.Protocol". (Contributed by Jelle Zijlstra in gh-104873.)

* Add "is_protocol()" to check whether a class is a "Protocol".
  (Contributed by Jelle Zijlstra in gh-104873.)

* "ClassVar" can now be nested in "Final", and vice versa.
  (Contributed by Mehdi Drissi in gh-89547.)


unicodedata
-----------

* Update the Unicode database to version 15.1.0. (Contributed by James
  Gerity in gh-109559.)


venv
----

* Add support for creating source control management (SCM) ignore
  files in a virtual environment's directory. By default, Git is
  supported. This is implemented as opt-in via the API, which can be
  extended to support other SCMs ("EnvBuilder" and "create()"), and
  opt-out via the CLI, using "--without-scm-ignore-files".
  (Contributed by Brett Cannon in gh-108125.)


warnings
--------

* **PEP 702**: The new "warnings.deprecated()" decorator provides a
  way to communicate deprecations to a *static type checker* and to
  warn on usage of deprecated classes and functions. A
  "DeprecationWarning" may also be emitted when a decorated function
  or class is used at runtime. (Contributed by Jelle Zijlstra in
  gh-104003.)


xml
---

* Allow controlling Expat >=2.6.0 reparse deferral (**CVE
  2023-52425**) by adding five new methods:

  * "xml.etree.ElementTree.XMLParser.flush()"

  * "xml.etree.ElementTree.XMLPullParser.flush()"

  * "xml.parsers.expat.xmlparser.GetReparseDeferralEnabled()"

  * "xml.parsers.expat.xmlparser.SetReparseDeferralEnabled()"

  * "xml.sax.expatreader.ExpatParser.flush()"

  (Contributed by Sebastian Pipping in gh-115623.)

* Add the "close()" method for the iterator returned by "iterparse()"
  for explicit cleanup. (Contributed by Serhiy Storchaka in gh-69893.)


zipimport
---------

* Add support for ZIP64 format files. Everybody loves huge data,
  right? (Contributed by Tim Hatch in gh-94146.)


Optimizations
=============

* Several standard library modules have had their import times
  significantly improved. For example, the import time of the "typing"
  module has been reduced by around a third by removing dependencies
  on "re" and "contextlib". Other modules to enjoy import-time
  speedups include "email.utils", "enum", "functools",
  "importlib.metadata", and "threading". (Contributed by Alex Waygood,
  Shantanu Jain, Adam Turner, Daniel Hollas, and others in gh-109653.)

* "textwrap.indent()" is now around 30% faster than before for large
  input. (Contributed by Inada Naoki in gh-107369.)

* The "subprocess" module now uses the "posix_spawn()" function in
  more situations, including when *close_fds* is "True" (the default)
  on many modern platforms. This should provide a notable performance
  increase when launching processes on FreeBSD and Solaris. See the
  subprocess section above for details. (Contributed by Jakub Kulik in
  gh-113117.)


Removed Modules And APIs
========================


PEP 594: Remove "dead batteries" from the standard library
----------------------------------------------------------

**PEP 594** proposed removing 19 modules from the standard library,
colloquially referred to as 'dead batteries' due to their historic,
obsolete, or insecure status. All of the following modules were
deprecated in Python 3.11, and are now removed:

* "aifc"

  * standard-aifc: Use the redistribution of "aifc" library from PyPI.

* "audioop"

  * audioop-lts: Use "audioop-lts" library from PyPI.

* "chunk"

  * standard-chunk: Use the redistribution of "chunk" library from
    PyPI.

* "cgi" and "cgitb"

  * "cgi.FieldStorage" can typically be replaced with
    "urllib.parse.parse_qsl()" for "GET" and "HEAD" requests, and the
    "email.message" module or the multipart library for "POST" and
    "PUT" requests.

  * "cgi.parse()" can be replaced by calling "urllib.parse.parse_qs()"
    directly on the desired query string, unless the input is
    "multipart/form-data", which should be replaced as described below
    for "cgi.parse_multipart()".

  * "cgi.parse_header()" can be replaced with the functionality in the
    "email" package, which implements the same MIME RFCs. For example,
    with "email.message.EmailMessage":

       from email.message import EmailMessage

       msg = EmailMessage()
       msg['content-type'] = 'application/json; charset="utf8"'
       main, params = msg.get_content_type(), msg['content-type'].params

  * "cgi.parse_multipart()" can be replaced with the functionality in
    the "email" package, which implements the same MIME RFCs, or with
    the multipart library. For example, the
    "email.message.EmailMessage" and "email.message.Message" classes.

  * standard-cgi: and standard-cgitb: Use the redistribution of "cgi"
    and "cgitb" library from PyPI.

* "crypt" and the private "_crypt" extension. The "hashlib" module may
  be an appropriate replacement when simply hashing a value is
  required. Otherwise, various third-party libraries on PyPI are
  available:

  * bcrypt: Modern password hashing for your software and your
    servers.

  * argon2-cffi: The secure Argon2 password hashing algorithm.

  * legacycrypt: "ctypes" wrapper to the POSIX crypt library call and
    associated functionality.

  * crypt_r: Fork of the "crypt" module, wrapper to the *crypt_r(3)*
    library call and associated functionality.

  * standard-crypt and deprecated-crypt-alternative: Use the
    redistribution of "crypt" and reimplementation of "_crypt"
    libraries from PyPI.

* "imghdr": The filetype, puremagic, or python-magic libraries should
  be used as replacements. For example, the "puremagic.what()"
  function can be used to replace the "imghdr.what()" function for all
  file formats that were supported by "imghdr".

  * standard-imghdr: Use the redistribution of "imghdr" library from
    PyPI.

* "mailcap": Use the "mimetypes" module instead.

  * standard-mailcap: Use the redistribution of "mailcap" library from
    PyPI.

* "msilib"

* "nis"

* "nntplib": Use the pynntp library from PyPI instead.

  * standard-nntplib: Use the redistribution of "nntplib" library from
    PyPI.

* "ossaudiodev": For audio playback, use the pygame library from PyPI
  instead.

* "pipes": Use the "subprocess" module instead. Use "shlex.quote()" to
  replace the undocumented "pipes.quote" function.

  * standard-pipes: Use the redistribution of "pipes" library from
    PyPI.

* "sndhdr": The filetype, puremagic, or python-magic libraries should
  be used as replacements.

  * standard-sndhdr: Use the redistribution of "sndhdr" library from
    PyPI.

* "spwd": Use the python-pam library from PyPI instead.

* "sunau"

  * standard-sunau: Use the redistribution of "sunau" library from
    PyPI.

* "telnetlib", Use the telnetlib3 or Exscript libraries from PyPI
  instead.

  * standard-telnetlib: Use the redistribution of "telnetlib" library
    from PyPI.

* "uu": Use the "base64" module instead, as a modern alternative.

  * standard-uu: Use the redistribution of "uu" library from PyPI.

* "xdrlib"

  * standard-xdrlib: Use the redistribution of "xdrlib" library from
    PyPI.

(Contributed by Victor Stinner and Zachary Ware in gh-104773 and
gh-104780.)


2to3
----

* Remove the **2to3** program and the "lib2to3" module, previously
  deprecated in Python 3.11. (Contributed by Victor Stinner in
  gh-104780.)


builtins
--------

* Remove support for chained "classmethod" descriptors (introduced in
  gh-63272). These can no longer be used to wrap other descriptors,
  such as "property". The core design of this feature was flawed and
  led to several problems. To "pass-through" a "classmethod", consider
  using the "__wrapped__" attribute that was added in Python 3.10.
  (Contributed by Raymond Hettinger in gh-89519.)

* Raise a "RuntimeError" when calling "frame.clear()" on a suspended
  frame (as has always been the case for an executing frame).
  (Contributed by Irit Katriel in gh-79932.)


configparser
------------

* Remove the undocumented "LegacyInterpolation" class, deprecated in
  the docstring since Python 3.2, and at runtime since Python 3.11.
  (Contributed by Hugo van Kemenade in gh-104886.)


importlib.metadata
------------------

* Remove deprecated subscript ("__getitem__()") access for EntryPoint
  objects. (Contributed by Jason R. Coombs in gh-113175.)


locale
------

* Remove the "locale.resetlocale()" function, deprecated in Python
  3.11. Use "locale.setlocale(locale.LC_ALL, "")" instead.
  (Contributed by Victor Stinner in gh-104783.)


opcode
------

* Move "opcode.ENABLE_SPECIALIZATION" to
  "_opcode.ENABLE_SPECIALIZATION". This field was added in 3.12, it
  was never documented, and is not intended for external use.
  (Contributed by Irit Katriel in gh-105481.)

* Remove "opcode.is_pseudo()", "opcode.MIN_PSEUDO_OPCODE", and
  "opcode.MAX_PSEUDO_OPCODE", which were added in Python 3.12, but
  were neither documented nor exposed through "dis", and were not
  intended to be used externally. (Contributed by Irit Katriel in
  gh-105481.)


optparse
--------

* This module is no longer considered *soft deprecated*. While
  "argparse" remains preferred for new projects that aren't using a
  third party command line argument processing library, there are
  aspects of the way "argparse" works that mean the lower level
  "optparse" module may provide a better foundation for *writing*
  argument processing libraries, and for implementing command line
  applications which adhere more strictly than "argparse" does to
  various Unix command line processing conventions that originate in
  the behaviour of the C "getopt()" function . (Contributed by Alyssa
  Coghlan and Serhiy Storchaka in gh-126180.)


pathlib
-------

* Remove the ability to use "Path" objects as context managers. This
  functionality was deprecated and has had no effect since Python 3.9.
  (Contributed by Barney Gale in gh-83863.)


re
--

* Remove the undocumented, deprecated, and broken "re.template()"
  function and "re.TEMPLATE" / "re.T" flag. (Contributed by Serhiy
  Storchaka and Nikita Sobolev in gh-105687.)


tkinter.tix
-----------

* Remove the "tkinter.tix" module, deprecated in Python 3.6. The
  third-party Tix library which the module wrapped is unmaintained.
  (Contributed by Zachary Ware in gh-75552.)


turtle
------

* Remove the "RawTurtle.settiltangle()" method, deprecated in the
  documentation since Python 3.1 and at runtime since Python 3.11.
  (Contributed by Hugo van Kemenade in gh-104876.)


typing
------

* Remove the "typing.io" and "typing.re" namespaces, deprecated since
  Python 3.8. The items in those namespaces can be imported directly
  from the "typing" module. (Contributed by Sebastian Rittau in
  gh-92871.)

* Remove the keyword-argument method of creating "TypedDict" types,
  deprecated in Python 3.11. (Contributed by Tomas Roun in gh-104786.)


unittest
--------

* Remove the following "unittest" functions, deprecated in Python
  3.11:

  * "unittest.findTestCases()"

  * "unittest.makeSuite()"

  * "unittest.getTestCaseNames()"

  Use "TestLoader" methods instead:

  * "loadTestsFromModule()"

  * "loadTestsFromTestCase()"

  * "getTestCaseNames()"

  (Contributed by Hugo van Kemenade in gh-104835.)

* Remove the untested and undocumented "TestProgram.usageExit()"
  method, deprecated in Python 3.11. (Contributed by Hugo van Kemenade
  in gh-104992.)


urllib
------

* Remove the *cafile*, *capath*, and *cadefault* parameters of the
  "urllib.request.urlopen()" function, deprecated in Python 3.6. Use
  the *context* parameter instead with an "SSLContext" instance. The
  "ssl.SSLContext.load_cert_chain()" function can be used to load
  specific certificates, or let "ssl.create_default_context()" select
  the operating system's trusted certificate authority (CA)
  certificates. (Contributed by Victor Stinner in gh-105382.)


webbrowser
----------

* Remove the untested and undocumented "MacOSX" class, deprecated in
  Python 3.11. Use the "MacOSXOSAScript" class (introduced in Python
  3.2) instead. (Contributed by Hugo van Kemenade in gh-104804.)

* Remove the deprecated "MacOSXOSAScript._name" attribute. Use the
  "MacOSXOSAScript.name" attribute instead. (Contributed by Nikita
  Sobolev in gh-105546.)


New Deprecations
================

* User-defined functions:

  * Deprecate assignment to a function's "__code__" attribute, where
    the new code object's type does not match the function's type. The
    different types are: plain function, generator, async generator,
    and coroutine. (Contributed by Irit Katriel in gh-81137.)

* "array":

  * Deprecate the "'u'" format code ("wchar_t") at runtime. This
    format code has been deprecated in documentation since Python 3.3,
    and will be removed in Python 3.16. Use the "'w'" format code
    ("Py_UCS4") for Unicode characters instead. (Contributed by Hugo
    van Kemenade in gh-80480.)

* "ctypes":

  * Deprecate the undocumented "SetPointerType()" function, to be
    removed in Python 3.15. (Contributed by Victor Stinner in
    gh-105733.)

  * *Soft-deprecate* the "ARRAY()" function in favour of "type *
    length" multiplication. (Contributed by Victor Stinner in
    gh-105733.)

* "decimal":

  * Deprecate the non-standard and undocumented "Decimal" format
    specifier "'N'", which is only supported in the "decimal" module's
    C implementation. (Contributed by Serhiy Storchaka in gh-89902.)

* "dis":

  * Deprecate the "HAVE_ARGUMENT" separator. Check membership in
    "hasarg" instead. (Contributed by Irit Katriel in gh-109319.)

* "gettext":

  * Deprecate non-integer numbers as arguments to functions and
    methods that consider plural forms in the "gettext" module, even
    if no translation was found. (Contributed by Serhiy Storchaka in
    gh-88434.)

* "glob":

  * Deprecate the undocumented "glob0()" and "glob1()" functions. Use
    "glob()" and pass a *path-like object* specifying the root
    directory to the *root_dir* parameter instead. (Contributed by
    Barney Gale in gh-117337.)

* "http.server":

  * Deprecate "CGIHTTPRequestHandler", to be removed in Python 3.15.
    Process-based CGI HTTP servers have been out of favor for a very
    long time. This code was outdated, unmaintained, and rarely used.
    It has a high potential for both security and functionality bugs.
    (Contributed by Gregory P. Smith in gh-109096.)

  * Deprecate the "--cgi" flag to the **python -m http.server**
    command-line interface, to be removed in Python 3.15. (Contributed
    by Gregory P. Smith in gh-109096.)

* "mimetypes":

  * *Soft-deprecate* file path arguments to "guess_type()", use
    "guess_file_type()" instead. (Contributed by Serhiy Storchaka in
    gh-66543.)

* "re":

  * Deprecate passing the optional *maxsplit*, *count*, or *flags*
    arguments as positional arguments to the module-level "split()",
    "sub()", and "subn()" functions. These parameters will become
    keyword-only in a future version of Python. (Contributed by Serhiy
    Storchaka in gh-56166.)

* "pathlib":

  * Deprecate "PurePath.is_reserved()", to be removed in Python 3.15.
    Use "os.path.isreserved()" to detect reserved paths on Windows.
    (Contributed by Barney Gale in gh-88569.)

* "platform":

  * Deprecate "java_ver()", to be removed in Python 3.15. This
    function is only useful for Jython support, has a confusing API,
    and is largely untested. (Contributed by Nikita Sobolev in
    gh-116349.)

* "pydoc":

  * Deprecate the undocumented "ispackage()" function. (Contributed by
    Zackery Spytz in gh-64020.)

* "sqlite3":

  * Deprecate passing more than one positional argument to the
    "connect()" function and the "Connection" constructor. The
    remaining parameters will become keyword-only in Python 3.15.
    (Contributed by Erlend E. Aasland in gh-107948.)

  * Deprecate passing name, number of arguments, and the callable as
    keyword arguments for "Connection.create_function()" and
    "Connection.create_aggregate()" These parameters will become
    positional-only in Python 3.15. (Contributed by Erlend E. Aasland
    in gh-108278.)

  * Deprecate passing the callback callable by keyword for the
    "set_authorizer()", "set_progress_handler()", and
    "set_trace_callback()" "Connection" methods. The callback
    callables will become positional-only in Python 3.15. (Contributed
    by Erlend E. Aasland in gh-108278.)

* "sys":

  * Deprecate the "_enablelegacywindowsfsencoding()" function, to be
    removed in Python 3.16. Use the "PYTHONLEGACYWINDOWSFSENCODING"
    environment variable instead. (Contributed by Inada Naoki in
    gh-73427.)

* "tarfile":

  * Deprecate the undocumented and unused "TarFile.tarfile" attribute,
    to be removed in Python 3.16. (Contributed in gh-115256.)

* "traceback":

  * Deprecate the "TracebackException.exc_type" attribute. Use
    "TracebackException.exc_type_str" instead. (Contributed by Irit
    Katriel in gh-112332.)

* "typing":

  * Deprecate the undocumented keyword argument syntax for creating
    "NamedTuple" classes (e.g. "Point = NamedTuple("Point", x=int,
    y=int)"), to be removed in Python 3.15. Use the class-based syntax
    or the functional syntax instead. (Contributed by Alex Waygood in
    gh-105566.)

  * Deprecate omitting the *fields* parameter when creating a
    "NamedTuple" or "typing.TypedDict" class, and deprecate passing
    "None" to the *fields* parameter of both types. Python 3.15 will
    require a valid sequence for the *fields* parameter. To create a
    NamedTuple class with zero fields, use "class NT(NamedTuple):
    pass" or "NT = NamedTuple("NT", ())". To create a TypedDict class
    with zero fields, use "class TD(TypedDict): pass" or "TD =
    TypedDict("TD", {})". (Contributed by Alex Waygood in gh-105566
    and gh-105570.)

  * Deprecate the "typing.no_type_check_decorator()" decorator
    function, to be removed in Python 3.15. After eight years in the
    "typing" module, it has yet to be supported by any major type
    checker. (Contributed by Alex Waygood in gh-106309.)

  * Deprecate "typing.AnyStr". In Python 3.16, it will be removed from
    "typing.__all__", and a "DeprecationWarning" will be emitted at
    runtime when it is imported or accessed. It will be removed
    entirely in Python 3.18. Use the new type parameter syntax
    instead. (Contributed by Michael The in gh-107116.)

* "wave":

  * Deprecate the "getmark()", "setmark()", and "getmarkers()" methods
    of the "Wave_read" and "Wave_write" classes, to be removed in
    Python 3.15. (Contributed by Victor Stinner in gh-105096.)


Pending removal in Python 3.14
------------------------------

* "argparse": The *type*, *choices*, and *metavar* parameters of
  "argparse.BooleanOptionalAction" are deprecated and will be removed
  in 3.14. (Contributed by Nikita Sobolev in gh-92248.)

* "ast": The following 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"

  Use "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.)

* "email": Deprecated the *isdst* parameter in
  "email.utils.localtime()". (Contributed by Alan Williams in
  gh-72346.)

* "importlib.abc" deprecated 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" had undocumented, inefficient, historically buggy, and
  inconsistent support for copy, deepcopy, and pickle operations. 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": The default 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'".  See 컨텍스트 및 시작 방법.

* "pathlib": "is_relative_to()" and "relative_to()": passing
  additional arguments is deprecated.

* "pkgutil": "pkgutil.find_loader()" and "pkgutil.get_loader()" now
  raise "DeprecationWarning"; use "importlib.util.find_spec()"
  instead. (Contributed by Nikita Sobolev in gh-97850.)

* "pty":

  * "master_open()": use "pty.openpty()".

  * "slave_open()": use "pty.openpty()".

* "sqlite3":

  * "version" and "version_info".

  * "execute()" and "executemany()" if named placeholders are used and
    *parameters* is a sequence instead of a "dict".

* "urllib": "urllib.parse.Quoter" is deprecated: it was not intended
  to be a public API. (Contributed by Gregory P. Smith in gh-88168.)


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)

* "ctypes":

  * The undocumented "ctypes.SetPointerType()" function has been
    deprecated since Python 3.13.

* "http.server":

  * 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.

* "importlib":

  * "load_module()" method: use "exec_module()" instead.

* "locale":

  * 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. Use
    "getlocale()", "setlocale()", and "getencoding()" instead.
    (Contributed by Hugo van Kemenade in gh-111187.)

* "pathlib":

  * "PurePath.is_reserved()" has been deprecated since Python 3.13.
    Use "os.path.isreserved()" to detect reserved paths on Windows.

* "platform":

  * "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.

* "sysconfig":

  * The *check_home* argument of "sysconfig.is_python_build()" has
    been deprecated since Python 3.12.

* "threading":

  * "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":

  * "types.CodeType": Accessing "co_lnotab" was deprecated in **PEP
    626** since 3.10 and was planned to be removed in 3.12, but it
    only got a proper "DeprecationWarning" in 3.12. May be removed in
    3.15. (Contributed by Nikita Sobolev in gh-101866.)

* "typing":

  * 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.

  * When using the functional syntax of "TypedDict"s, failing to pass
    a value to the *fields* parameter ("TD = TypedDict("TD")") or
    passing "None" ("TD = TypedDict("TD", None)") has been deprecated
    since Python 3.13. Use "class TD(TypedDict): pass" or "TD =
    TypedDict("TD", {})" to create a TypedDict with zero field.

  * The "typing.no_type_check_decorator()" decorator function has been
    deprecated since Python 3.13. After eight years in the "typing"
    module, it has yet to be supported by any major type checker.

* "wave":

  * The "getmark()", "setmark()", and "getmarkers()" methods of the
    "Wave_read" and "Wave_write" classes have been deprecated since
    Python 3.13.

* "zipimport":

  * "load_module()" has been deprecated since Python 3.10. Use
    "exec_module()" instead. (Contributed by Jiahao Li in gh-125746.)


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.

* "array":

  * 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":

  * "asyncio.iscoroutinefunction()" is deprecated and will be removed
    in Python 3.16; use "inspect.iscoroutinefunction()" instead.
    (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)

  * "asyncio" policy system is deprecated and will be removed in
    Python 3.16. In particular, the following classes and functions
    are deprecated:

    * "asyncio.AbstractEventLoopPolicy"

    * "asyncio.DefaultEventLoopPolicy"

    * "asyncio.WindowsSelectorEventLoopPolicy"

    * "asyncio.WindowsProactorEventLoopPolicy"

    * "asyncio.get_event_loop_policy()"

    * "asyncio.set_event_loop_policy()"

    Users should use "asyncio.run()" or "asyncio.Runner" with
    *loop_factory* to use the desired event loop implementation.

    For example, to use "asyncio.SelectorEventLoop" on Windows:

       import asyncio

       async def main():
           ...

       asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop)

    (Contributed by Kumar Aditya in gh-127949.)

* "builtins":

  * Bitwise inversion on boolean types, "~True" or "~False" has been
    deprecated since Python 3.12, as it produces surprising and
    unintuitive results ("-2" and "-1"). Use "not x" instead for the
    logical negation of a Boolean. In the rare case that you need the
    bitwise inversion of the underlying integer, convert to "int"
    explicitly ("~int(x)").

* "functools":

  * Calling the Python implementation of "functools.reduce()" with
    *function* or *sequence* as keyword arguments has been deprecated
    since Python 3.14.

* "logging":

  Support for custom logging handlers with the *strm* argument is
  deprecated and scheduled for removal in Python 3.16. Define handlers
  with the *stream* argument instead. (Contributed by Mariusz Felisiak
  in gh-115032.)

* "mimetypes":

  * Valid extensions start with a '.' or are empty for
    "mimetypes.MimeTypes.add_type()". Undotted extensions are
    deprecated and will raise a "ValueError" in Python 3.16.
    (Contributed by Hugo van Kemenade in gh-75223.)

* "shutil":

  * The "ExecError" exception has been deprecated since Python 3.14.
    It has not been used by any function in "shutil" since Python 3.4,
    and is now an alias of "RuntimeError".

* "symtable":

  * The "Class.get_methods" method has been deprecated since Python
    3.14.

* "sys":

  * The "_enablelegacywindowsfsencoding()" function has been
    deprecated since Python 3.13. Use the
    "PYTHONLEGACYWINDOWSFSENCODING" environment variable instead.

* "sysconfig":

  * The "sysconfig.expand_makefile_vars()" function has been
    deprecated since Python 3.14. Use the "vars" argument of
    "sysconfig.get_paths()" instead.

* "tarfile":

  * The undocumented and unused "TarFile.tarfile" attribute has been
    deprecated since Python 3.13.


Pending removal in Python 3.17
------------------------------

* "collections.abc":

  * "collections.abc.ByteString" is scheduled for removal in Python
    3.17.

    Use "isinstance(obj, collections.abc.Buffer)" to test if "obj"
    implements the buffer protocol at runtime. For use in type
    annotations, either use "Buffer" or a union that explicitly
    specifies the types your code supports (e.g., "bytes | bytearray |
    memoryview").

    "ByteString" was originally intended to be an abstract class that
    would serve as a supertype of both "bytes" and "bytearray".
    However, since the ABC never had any methods, knowing that an
    object was an instance of "ByteString" never actually told you
    anything useful about the object. Other common buffer types such
    as "memoryview" were also never understood as subtypes of
    "ByteString" (either at runtime or by static type checkers).

    See **PEP 688** for more details. (Contributed by Shantanu Jain in
    gh-91896.)

* "typing":

  * Before Python 3.14, old-style unions were implemented using the
    private class "typing._UnionGenericAlias". This class is no longer
    needed for the implementation, but it has been retained for
    backward compatibility, with removal scheduled for Python 3.17.
    Users should use documented introspection helpers like
    "typing.get_origin()" and "typing.get_args()" instead of relying
    on private implementation details.

  * "typing.ByteString", deprecated since Python 3.9, is scheduled for
    removal in Python 3.17.

    Use "isinstance(obj, collections.abc.Buffer)" to test if "obj"
    implements the buffer protocol at runtime. For use in type
    annotations, either use "Buffer" or a union that explicitly
    specifies the types your code supports (e.g., "bytes | bytearray |
    memoryview").

    "ByteString" was originally intended to be an abstract class that
    would serve as a supertype of both "bytes" and "bytearray".
    However, since the ABC never had any methods, knowing that an
    object was an instance of "ByteString" never actually told you
    anything useful about the object. Other common buffer types such
    as "memoryview" were also never understood as subtypes of
    "ByteString" (either at runtime or by static type checkers).

    See **PEP 688** for more details. (Contributed by Shantanu Jain in
    gh-91896.)


Pending removal in future versions
----------------------------------

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

* "argparse":

  * Nesting argument groups and nesting mutually exclusive groups are
    deprecated.

  * Passing the undocumented keyword argument *prefix_chars* to
    "add_argument_group()" is now deprecated.

  * The "argparse.FileType" type converter is deprecated.

* "builtins":

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

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

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

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

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

  * Delegation of "int()" to "__trunc__()" method.

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

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

* "codecs": use "open()" instead of "codecs.open()". (gh-133038)

* "codeobject.co_lnotab": use the "codeobject.co_lines()" method
  instead.

* "datetime":

  * "utcnow()": use "datetime.datetime.now(tz=datetime.UTC)".

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

* "gettext": Plural value must be an integer.

* "importlib":

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

* "importlib.metadata":

  * "EntryPoints" tuple interface.

  * Implicit "None" on return values.

* "logging": the "warn()" method has been deprecated since Python 3.3,
  use "warning()" instead.

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

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

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

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

* "sre_compile", "sre_constants" and "sre_parse" modules.

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

* "ssl" options and protocols:

  * "ssl.SSLContext" without protocol argument is deprecated.

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

  * "ssl.OP_NO_SSL*" options

  * "ssl.OP_NO_TLS*" options

  * "ssl.PROTOCOL_SSLv3"

  * "ssl.PROTOCOL_TLS"

  * "ssl.PROTOCOL_TLSv1"

  * "ssl.PROTOCOL_TLSv1_1"

  * "ssl.PROTOCOL_TLSv1_2"

  * "ssl.TLSVersion.SSLv3"

  * "ssl.TLSVersion.TLSv1"

  * "ssl.TLSVersion.TLSv1_1"

* "threading" methods:

  * "threading.Condition.notifyAll()": use "notify_all()".

  * "threading.Event.isSet()": use "is_set()".

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

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

  * "threading.currentThread()": use "threading.current_thread()".

  * "threading.activeCount()": use "threading.active_count()".

* "typing.Text" (gh-92332).

* The internal class "typing._UnionGenericAlias" is no longer used to
  implement "typing.Union". To preserve compatibility with users using
  this private class, a compatibility shim will be provided until at
  least Python 3.17. (Contributed by Jelle Zijlstra in gh-105499.)

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

* "urllib.parse" deprecated functions: "urlparse()" instead

  * "splitattr()"

  * "splithost()"

  * "splitnport()"

  * "splitpasswd()"

  * "splitport()"

  * "splitquery()"

  * "splittag()"

  * "splittype()"

  * "splituser()"

  * "splitvalue()"

  * "to_bytes()"

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

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

* "sys._clear_type_cache()" is deprecated: use
  "sys._clear_internal_caches()" instead.


CPython Bytecode Changes
========================

* The oparg of "YIELD_VALUE" is now "1" if the yield is part of a
  yield-from or await, and "0" otherwise. The oparg of "RESUME" was
  changed to add a bit indicating if the except-depth is 1, which is
  needed to optimize closing of generators. (Contributed by Irit
  Katriel in gh-111354.)


C API Changes
=============


새로운 기능들
-------------

* Add the PyMonitoring C API for generating **PEP 669** monitoring
  events:

  * "PyMonitoringState"

  * "PyMonitoring_FirePyStartEvent()"

  * "PyMonitoring_FirePyResumeEvent()"

  * "PyMonitoring_FirePyReturnEvent()"

  * "PyMonitoring_FirePyYieldEvent()"

  * "PyMonitoring_FireCallEvent()"

  * "PyMonitoring_FireLineEvent()"

  * "PyMonitoring_FireJumpEvent()"

  * "PyMonitoring_FireBranchEvent"

  * "PyMonitoring_FireCReturnEvent()"

  * "PyMonitoring_FirePyThrowEvent()"

  * "PyMonitoring_FireRaiseEvent()"

  * "PyMonitoring_FireCRaiseEvent()"

  * "PyMonitoring_FireReraiseEvent()"

  * "PyMonitoring_FireExceptionHandledEvent()"

  * "PyMonitoring_FirePyUnwindEvent()"

  * "PyMonitoring_FireStopIterationEvent()"

  * "PyMonitoring_EnterScope()"

  * "PyMonitoring_ExitScope()"

  (Contributed by Irit Katriel in gh-111997).

* Add "PyMutex", a lightweight mutex that occupies a single byte, and
  the new "PyMutex_Lock()" and "PyMutex_Unlock()" functions.
  "PyMutex_Lock()" will release the *GIL* (if currently held) if the
  operation needs to block. (Contributed by Sam Gross in gh-108724.)

* Add the PyTime C API to provide access to system clocks:

  * "PyTime_t".

  * "PyTime_MIN" and "PyTime_MAX".

  * "PyTime_AsSecondsDouble()".

  * "PyTime_Monotonic()".

  * "PyTime_MonotonicRaw()".

  * "PyTime_PerfCounter()".

  * "PyTime_PerfCounterRaw()".

  * "PyTime_Time()".

  * "PyTime_TimeRaw()".

  (Contributed by Victor Stinner and Petr Viktorin in gh-110850.)

* Add the "PyDict_ContainsString()" function with the same behavior as
  "PyDict_Contains()", but *key* is specified as a const char* UTF-8
  encoded bytes string, rather than a PyObject*. (Contributed by
  Victor Stinner in gh-108314.)

* Add the "PyDict_GetItemRef()" and "PyDict_GetItemStringRef()"
  functions, which behave similarly to "PyDict_GetItemWithError()",
  but return a  *strong reference* instead of a *borrowed reference*.
  Moreover, these functions return "-1" on error, removing the need to
  check "PyErr_Occurred()". (Contributed by Victor Stinner in
  gh-106004.)

* Add the "PyDict_SetDefaultRef()" function, which behaves similarly
  to "PyDict_SetDefault()", but returns a *strong reference* instead
  of a *borrowed reference*. This function returns "-1" on error, "0"
  on insertion, and "1" if the key was already present in the
  dictionary. (Contributed by Sam Gross in gh-112066.)

* Add the "PyDict_Pop()" and "PyDict_PopString()" functions to remove
  a key from a dictionary and optionally return the removed value.
  This is similar to "dict.pop()", though there is no default value,
  and "KeyError" is not raised for missing keys. (Contributed by
  Stefan Behnel and Victor Stinner in gh-111262.)

* Add the "PyMapping_GetOptionalItem()" and
  "PyMapping_GetOptionalItemString()" functions as alternatives to
  "PyObject_GetItem()" and "PyMapping_GetItemString()" respectively.
  The new functions do not raise "KeyError" if the requested key is
  missing from the mapping. These variants are more convenient and
  faster if a missing key should not be treated as a failure.
  (Contributed by Serhiy Storchaka in gh-106307.)

* Add the "PyObject_GetOptionalAttr()" and
  "PyObject_GetOptionalAttrString()" functions as alternatives to
  "PyObject_GetAttr()" and "PyObject_GetAttrString()" respectively.
  The new functions do not raise "AttributeError" if the requested
  attribute is not found on the object. These variants are more
  convenient and faster if the missing attribute should not be treated
  as a failure. (Contributed by Serhiy Storchaka in gh-106521.)

* Add the "PyErr_FormatUnraisable()" function as an extension to
  "PyErr_WriteUnraisable()" that allows customizing the warning
  message. (Contributed by Serhiy Storchaka in gh-108082.)

* Add new functions that return a *strong reference* instead of a
  *borrowed reference* for frame locals, globals, and builtins, as
  part of PEP 667:

  * "PyEval_GetFrameBuiltins()" replaces "PyEval_GetBuiltins()"

  * "PyEval_GetFrameGlobals()" replaces "PyEval_GetGlobals()"

  * "PyEval_GetFrameLocals()" replaces "PyEval_GetLocals()"

  (Contributed by Mark Shannon and Tian Gao in gh-74929.)

* Add the "Py_GetConstant()" and "Py_GetConstantBorrowed()" functions
  to get *strong* or *borrowed* references to constants. For example,
  "Py_GetConstant(Py_CONSTANT_ZERO)" returns a strong reference to the
  constant zero. (Contributed by Victor  Stinner in gh-115754.)

* Add the "PyImport_AddModuleRef()" function as a replacement for
  "PyImport_AddModule()" that returns a *strong reference* instead of
  a *borrowed reference*. (Contributed by Victor Stinner in
  gh-105922.)

* Add the "Py_IsFinalizing()" function to check whether the main
  Python interpreter is *shutting down*. (Contributed by Victor
  Stinner in gh-108014.)

* Add the "PyList_GetItemRef()" function as a replacement for
  "PyList_GetItem()" that returns a *strong reference* instead of a
  *borrowed reference*. (Contributed by Sam Gross in gh-114329.)

* Add the "PyList_Extend()" and "PyList_Clear()" functions, mirroring
  the Python "list.extend()" and "list.clear()" methods. (Contributed
  by Victor Stinner in gh-111138.)

* Add the "PyLong_AsInt()" function. It behaves similarly to
  "PyLong_AsLong()", but stores the result in a C int instead of a C
  long. (Contributed by Victor Stinner in gh-108014.)

* Add the "PyLong_AsNativeBytes()", "PyLong_FromNativeBytes()", and
  "PyLong_FromUnsignedNativeBytes()" functions to simplify converting
  between native integer types and Python "int" objects. (Contributed
  by Steve Dower in gh-111140.)

* Add "PyModule_Add()" function, which is similar to
  "PyModule_AddObjectRef()" and "PyModule_AddObject()", but always
  steals a reference to the value. (Contributed by Serhiy Storchaka in
  gh-86493.)

* Add the "PyObject_GenericHash()" function that implements the
  default hashing function of a Python object. (Contributed by Serhiy
  Storchaka in gh-113024.)

* Add the "Py_HashPointer()" function to hash a raw pointer.
  (Contributed by Victor Stinner in gh-111545.)

* Add the "PyObject_VisitManagedDict()" and
  "PyObject_ClearManagedDict()" functions. which must be called by the
  traverse and clear functions of a type using the
  "Py_TPFLAGS_MANAGED_DICT" flag. The pythoncapi-compat project can be
  used to use these functions with Python 3.11 and 3.12. (Contributed
  by Victor Stinner in gh-107073.)

* Add the "PyRefTracer_SetTracer()" and "PyRefTracer_GetTracer()"
  functions, which enable tracking object creation and destruction in
  the same way that the "tracemalloc" module does. (Contributed by
  Pablo Galindo in gh-93502.)

* Add the "PySys_AuditTuple()" function as an alternative to
  "PySys_Audit()" that takes event arguments as a Python "tuple"
  object. (Contributed by Victor Stinner in gh-85283.)

* Add the "PyThreadState_GetUnchecked()" function as an alternative to
  "PyThreadState_Get()" that doesn't kill the process with a fatal
  error if it is "NULL". The caller is responsible for checking if the
  result is "NULL". (Contributed by Victor Stinner in gh-108867.)

* Add the "PyType_GetFullyQualifiedName()" function to get the type's
  fully qualified name. The module name is prepended if
  "type.__module__" is a string and is not equal to either
  "'builtins'" or "'__main__'". (Contributed by Victor Stinner in
  gh-111696.)

* Add the "PyType_GetModuleName()" function to get the type's module
  name. This is equivalent to getting the "type.__module__" attribute.
  (Contributed by Eric Snow and Victor Stinner in gh-111696.)

* Add the "PyUnicode_EqualToUTF8AndSize()" and
  "PyUnicode_EqualToUTF8()" functions to compare a Unicode object with
  a const char* UTF-8 encoded string and "1" if they are equal or "0"
  otherwise. These functions do not raise exceptions. (Contributed by
  Serhiy Storchaka in gh-110289.)

* Add the "PyWeakref_GetRef()" function as an alternative to
  "PyWeakref_GetObject()" that returns a *strong reference* or "NULL"
  if the referent is no longer live. (Contributed by Victor Stinner in
  gh-105927.)

* Add fixed variants of functions which silently ignore errors:

  * "PyObject_HasAttrWithError()" replaces "PyObject_HasAttr()".

  * "PyObject_HasAttrStringWithError()" replaces
    "PyObject_HasAttrString()".

  * "PyMapping_HasKeyWithError()" replaces "PyMapping_HasKey()".

  * "PyMapping_HasKeyStringWithError()" replaces
    "PyMapping_HasKeyString()".

  The new functions return "-1" for errors and the standard "1" for
  true and "0" for false.

  (Contributed by Serhiy Storchaka in gh-108511.)


Changed C APIs
--------------

* The *keywords* parameter of "PyArg_ParseTupleAndKeywords()" and
  "PyArg_VaParseTupleAndKeywords()" now has type char *const* in C and
  const char *const* in C++, instead of char**. In C++, this makes
  these functions compatible with arguments of type const char
  *const*, const char**, or char *const* without an explicit type
  cast. In C, the functions only support arguments of type char
  *const*. This can be overridden with the "PY_CXX_CONST" macro.
  (Contributed by Serhiy Storchaka in gh-65210.)

* "PyArg_ParseTupleAndKeywords()" now supports non-ASCII keyword
  parameter names. (Contributed by Serhiy Storchaka in gh-110815.)

* The "PyCode_GetFirstFree()" function is now unstable API and is now
  named "PyUnstable_Code_GetFirstFree()". (Contributed by Bogdan
  Romanyuk in gh-115781.)

* The "PyDict_GetItem()", "PyDict_GetItemString()",
  "PyMapping_HasKey()", "PyMapping_HasKeyString()",
  "PyObject_HasAttr()", "PyObject_HasAttrString()", and
  "PySys_GetObject()" functions, each of which clears all errors which
  occurred when calling them now reports these errors using
  "sys.unraisablehook()". You may replace them with other functions as
  recommended in the documentation. (Contributed by Serhiy Storchaka
  in gh-106672.)

* Add support for the "%T", "%#T", "%N" and "%#N" formats to
  "PyUnicode_FromFormat()":

  * "%T": Get the fully qualified name of an object type

  * "%#T": As above, but use a colon as the separator

  * "%N": Get the fully qualified name of a type

  * "%#N": As above, but use a colon as the separator

  See **PEP 737** for more information. (Contributed by Victor Stinner
  in gh-111696.)

* You no longer have to define the "PY_SSIZE_T_CLEAN" macro before
  including "Python.h" when using "#" formats in format codes. APIs
  accepting the format codes always use "Py_ssize_t" for "#" formats.
  (Contributed by Inada Naoki in gh-104922.)

* If Python is built in debug mode or "with assertions",
  "PyTuple_SET_ITEM()" and "PyList_SET_ITEM()" now check the index
  argument with an assertion. (Contributed by Victor Stinner in
  gh-106168.)


Limited C API Changes
---------------------

* The following functions are now included in the Limited C API:

  * "PyMem_RawMalloc()"

  * "PyMem_RawCalloc()"

  * "PyMem_RawRealloc()"

  * "PyMem_RawFree()"

  * "PySys_Audit()"

  * "PySys_AuditTuple()"

  * "PyType_GetModuleByDef()"

  (Contributed by Victor Stinner in gh-85283, gh-85283, and
  gh-116936.)

* Python built with "--with-trace-refs" (tracing references) now
  supports the Limited API. (Contributed by Victor Stinner in
  gh-108634.)


Removed C APIs
--------------

* Remove several functions, macros, variables, etc with names prefixed
  by "_Py" or "_PY" (which are considered private). If your project is
  affected  by one of these removals and you believe that the removed
  API should remain available, please open a new issue to request a
  public C API and add "cc: @vstinner" to the issue to notify Victor
  Stinner. (Contributed by Victor Stinner in gh-106320.)

* Remove old buffer protocols deprecated in Python 3.0. Use 버퍼 프로
  토콜 instead.

  * "PyObject_CheckReadBuffer()": Use "PyObject_CheckBuffer()" to test
    whether the object supports the buffer protocol. Note that
    "PyObject_CheckBuffer()" doesn't guarantee that
    "PyObject_GetBuffer()" will succeed. To test if the object is
    actually readable, see the next example of "PyObject_GetBuffer()".

  * "PyObject_AsCharBuffer()", "PyObject_AsReadBuffer()": Use
    "PyObject_GetBuffer()" and "PyBuffer_Release()" instead:

       Py_buffer view;
       if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) {
           return NULL;
       }
       // Use `view.buf` and `view.len` to read from the buffer.
       // You may need to cast buf as `(const char*)view.buf`.
       PyBuffer_Release(&view);

  * "PyObject_AsWriteBuffer()": Use "PyObject_GetBuffer()" and
    "PyBuffer_Release()" instead:

       Py_buffer view;
       if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) {
           return NULL;
       }
       // Use `view.buf` and `view.len` to write to the buffer.
       PyBuffer_Release(&view);

  (Contributed by Inada Naoki in gh-85275.)

* Remove various functions deprecated in Python 3.9:

  * "PyEval_CallObject()", "PyEval_CallObjectWithKeywords()": Use
    "PyObject_CallNoArgs()" or "PyObject_Call()" instead.

    경고:

      In "PyObject_Call()", positional arguments must be a "tuple" and
      must not be "NULL", and keyword arguments must be a "dict" or
      "NULL", whereas the removed functions checked argument types and
      accepted "NULL" positional and keyword arguments. To replace
      "PyEval_CallObjectWithKeywords(func, NULL, kwargs)" with
      "PyObject_Call()", pass an empty tuple as positional arguments
      using "PyTuple_New(0)".

  * "PyEval_CallFunction()": Use "PyObject_CallFunction()" instead.

  * "PyEval_CallMethod()": Use "PyObject_CallMethod()" instead.

  * "PyCFunction_Call()": Use "PyObject_Call()" instead.

  (Contributed by Victor Stinner in gh-105107.)

* Remove the following old functions to configure the Python
  initialization, deprecated in Python 3.11:

  * "PySys_AddWarnOptionUnicode()": Use "PyConfig.warnoptions"
    instead.

  * "PySys_AddWarnOption()": Use "PyConfig.warnoptions" instead.

  * "PySys_AddXOption()": Use "PyConfig.xoptions" instead.

  * "PySys_HasWarnOptions()": Use "PyConfig.xoptions" instead.

  * "PySys_SetPath()": Set "PyConfig.module_search_paths" instead.

  * "Py_SetPath()": Set "PyConfig.module_search_paths" instead.

  * "Py_SetStandardStreamEncoding()": Set "PyConfig.stdio_encoding"
    instead, and set also maybe "PyConfig.legacy_windows_stdio" (on
    Windows).

  * "_Py_SetProgramFullPath()": Set "PyConfig.executable" instead.

  Use the new "PyConfig" API of the Python Initialization
  Configuration instead (**PEP 587**), added to Python 3.8.
  (Contributed by Victor Stinner in gh-105145.)

* Remove "PyEval_AcquireLock()" and "PyEval_ReleaseLock()" functions,
  deprecated in Python 3.2. They didn't update the current thread
  state. They can be replaced with:

  * "PyEval_SaveThread()" and "PyEval_RestoreThread()";

  * low-level "PyEval_AcquireThread()" and "PyEval_RestoreThread()";

  * or "PyGILState_Ensure()" and "PyGILState_Release()".

  (Contributed by Victor Stinner in gh-105182.)

* Remove the "PyEval_ThreadsInitialized()" function, deprecated in
  Python 3.9. Since Python 3.7, "Py_Initialize()" always creates the
  GIL: calling "PyEval_InitThreads()" does nothing and
  "PyEval_ThreadsInitialized()" always returns non-zero. (Contributed
  by Victor Stinner in gh-105182.)

* Remove the "_PyInterpreterState_Get()" alias to
  "PyInterpreterState_Get()" which was kept for backward compatibility
  with Python 3.8. The pythoncapi-compat project can be used to get
  "PyInterpreterState_Get()" on Python 3.8 and older. (Contributed by
  Victor Stinner in gh-106320.)

* Remove the private "_PyObject_FastCall()" function: use
  "PyObject_Vectorcall()" which is available since Python 3.8 (**PEP
  590**). (Contributed by Victor Stinner in gh-106023.)

* Remove the "cpython/pytime.h" header file, which only contained
  private functions. (Contributed by Victor Stinner in gh-106316.)

* Remove the undocumented "PY_TIMEOUT_MAX" constant from the limited C
  API. (Contributed by Victor Stinner in gh-110014.)

* Remove the old trashcan macros "Py_TRASHCAN_SAFE_BEGIN" and
  "Py_TRASHCAN_SAFE_END". Replace both with the new macros
  "Py_TRASHCAN_BEGIN" and "Py_TRASHCAN_END". (Contributed by Irit
  Katriel in gh-105111.)


Deprecated C APIs
-----------------

* Deprecate old Python initialization functions:

  * "PySys_ResetWarnOptions()": Clear "sys.warnoptions" and
    "warnings.filters" instead.

  * "Py_GetExecPrefix()": Get "sys.exec_prefix" instead.

  * "Py_GetPath()": Get "sys.path" instead.

  * "Py_GetPrefix()": Get "sys.prefix" instead.

  * "Py_GetProgramFullPath()": Get "sys.executable" instead.

  * "Py_GetProgramName()": Get "sys.executable" instead.

  * "Py_GetPythonHome()": Get "PyConfig.home" or the "PYTHONHOME"
    environment variable instead.

  (Contributed by Victor Stinner in gh-105145.)

* *Soft deprecate* the "PyEval_GetBuiltins()", "PyEval_GetGlobals()",
  and "PyEval_GetLocals()" functions, which return a *borrowed
  reference*. (Soft deprecated as part of **PEP 667**.)

* Deprecate the "PyImport_ImportModuleNoBlock()" function, which is
  just an alias to "PyImport_ImportModule()" since Python 3.3.
  (Contributed by Victor Stinner in gh-105396.)

* *Soft deprecate* the "PyModule_AddObject()" function. It should be
  replaced with "PyModule_Add()" or "PyModule_AddObjectRef()".
  (Contributed by Serhiy Storchaka in gh-86493.)

* Deprecate the old "Py_UNICODE" and "PY_UNICODE_TYPE" types and the
  "Py_UNICODE_WIDE" define. Use the "wchar_t" type directly instead.
  Since Python 3.3, "Py_UNICODE" and "PY_UNICODE_TYPE" are just
  aliases to "wchar_t". (Contributed by Victor Stinner in gh-105156.)

* Deprecate the "PyWeakref_GetObject()" and "PyWeakref_GET_OBJECT()"
  functions, which return a *borrowed reference*. Replace them with
  the new "PyWeakref_GetRef()" function, which returns a *strong
  reference*. The pythoncapi-compat project can be used to get
  "PyWeakref_GetRef()" on Python 3.12 and older. (Contributed by
  Victor Stinner in gh-105927.)


Pending removal in Python 3.14
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* The "ma_version_tag" field in "PyDictObject" for extension modules
  (**PEP 699**; gh-101193).

* Creating "immutable types" with mutable bases (gh-95388).


Pending removal in Python 3.15
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* The "PyImport_ImportModuleNoBlock()": Use "PyImport_ImportModule()"
  instead.

* "PyWeakref_GetObject()" and "PyWeakref_GET_OBJECT()": Use
  "PyWeakref_GetRef()" instead. The pythoncapi-compat project can be
  used to get "PyWeakref_GetRef()" on Python 3.12 and older.

* "Py_UNICODE" type and the "Py_UNICODE_WIDE" macro: Use "wchar_t"
  instead.

* "PyUnicode_AsDecodedObject()": Use "PyCodec_Decode()" instead.

* "PyUnicode_AsDecodedUnicode()": Use "PyCodec_Decode()" instead; Note
  that some codecs (for example, "base64") may return a type other
  than "str", such as "bytes".

* "PyUnicode_AsEncodedObject()": Use "PyCodec_Encode()" instead.

* "PyUnicode_AsEncodedUnicode()": Use "PyCodec_Encode()" instead; Note
  that some codecs (for example, "base64") may return a type other
  than "bytes", such as "str".

* Python initialization functions, deprecated in Python 3.13:

  * "Py_GetPath()": Use "PyConfig_Get("module_search_paths")"
    ("sys.path") instead.

  * "Py_GetPrefix()": Use "PyConfig_Get("base_prefix")"
    ("sys.base_prefix") instead. Use "PyConfig_Get("prefix")"
    ("sys.prefix") if virtual environments need to be handled.

  * "Py_GetExecPrefix()": Use "PyConfig_Get("base_exec_prefix")"
    ("sys.base_exec_prefix") instead. Use
    "PyConfig_Get("exec_prefix")" ("sys.exec_prefix") if virtual
    environments need to be handled.

  * "Py_GetProgramFullPath()": Use "PyConfig_Get("executable")"
    ("sys.executable") instead.

  * "Py_GetProgramName()": Use "PyConfig_Get("executable")"
    ("sys.executable") instead.

  * "Py_GetPythonHome()": Use "PyConfig_Get("home")" or the
    "PYTHONHOME" environment variable instead.

  The pythoncapi-compat project can be used to get "PyConfig_Get()" on
  Python 3.13 and older.

* Functions to configure Python's initialization, deprecated in Python
  3.11:

  * "PySys_SetArgvEx()": Set "PyConfig.argv" instead.

  * "PySys_SetArgv()": Set "PyConfig.argv" instead.

  * "Py_SetProgramName()": Set "PyConfig.program_name" instead.

  * "Py_SetPythonHome()": Set "PyConfig.home" instead.

  * "PySys_ResetWarnOptions()": Clear "sys.warnoptions" and
    "warnings.filters" instead.

  The "Py_InitializeFromConfig()" API should be used with "PyConfig"
  instead.

* Global configuration variables:

  * "Py_DebugFlag": Use "PyConfig.parser_debug" or
    "PyConfig_Get("parser_debug")" instead.

  * "Py_VerboseFlag": Use "PyConfig.verbose" or
    "PyConfig_Get("verbose")" instead.

  * "Py_QuietFlag": Use "PyConfig.quiet" or "PyConfig_Get("quiet")"
    instead.

  * "Py_InteractiveFlag": Use "PyConfig.interactive" or
    "PyConfig_Get("interactive")" instead.

  * "Py_InspectFlag": Use "PyConfig.inspect" or
    "PyConfig_Get("inspect")" instead.

  * "Py_OptimizeFlag": Use "PyConfig.optimization_level" or
    "PyConfig_Get("optimization_level")" instead.

  * "Py_NoSiteFlag": Use "PyConfig.site_import" or
    "PyConfig_Get("site_import")" instead.

  * "Py_BytesWarningFlag": Use "PyConfig.bytes_warning" or
    "PyConfig_Get("bytes_warning")" instead.

  * "Py_FrozenFlag": Use "PyConfig.pathconfig_warnings" or
    "PyConfig_Get("pathconfig_warnings")" instead.

  * "Py_IgnoreEnvironmentFlag": Use "PyConfig.use_environment" or
    "PyConfig_Get("use_environment")" instead.

  * "Py_DontWriteBytecodeFlag": Use "PyConfig.write_bytecode" or
    "PyConfig_Get("write_bytecode")" instead.

  * "Py_NoUserSiteDirectory": Use "PyConfig.user_site_directory" or
    "PyConfig_Get("user_site_directory")" instead.

  * "Py_UnbufferedStdioFlag": Use "PyConfig.buffered_stdio" or
    "PyConfig_Get("buffered_stdio")" instead.

  * "Py_HashRandomizationFlag": Use "PyConfig.use_hash_seed" and
    "PyConfig.hash_seed" or "PyConfig_Get("hash_seed")" instead.

  * "Py_IsolatedFlag": Use "PyConfig.isolated" or
    "PyConfig_Get("isolated")" instead.

  * "Py_LegacyWindowsFSEncodingFlag": Use
    "PyPreConfig.legacy_windows_fs_encoding" or
    "PyConfig_Get("legacy_windows_fs_encoding")" instead.

  * "Py_LegacyWindowsStdioFlag": Use "PyConfig.legacy_windows_stdio"
    or "PyConfig_Get("legacy_windows_stdio")" instead.

  * "Py_FileSystemDefaultEncoding", "Py_HasFileSystemDefaultEncoding":
    Use "PyConfig.filesystem_encoding" or
    "PyConfig_Get("filesystem_encoding")" instead.

  * "Py_FileSystemDefaultEncodeErrors": Use
    "PyConfig.filesystem_errors" or
    "PyConfig_Get("filesystem_errors")" instead.

  * "Py_UTF8Mode": Use "PyPreConfig.utf8_mode" or
    "PyConfig_Get("utf8_mode")" instead. (see "Py_PreInitialize()")

  The "Py_InitializeFromConfig()" API should be used with "PyConfig"
  to set these options. Or "PyConfig_Get()" can be used to get these
  options at runtime.


Pending removal in Python 3.16
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* The bundled copy of "libmpdec".


Pending removal in Python 3.18
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* The following private functions are deprecated and planned for
  removal in Python 3.18:

  * "_PyBytes_Join()": use "PyBytes_Join()".

  * "_PyDict_GetItemStringWithError()": use
    "PyDict_GetItemStringRef()".

  * "_PyDict_Pop()": use "PyDict_Pop()".

  * "_PyLong_Sign()": use "PyLong_GetSign()".

  * "_PyLong_FromDigits()" and "_PyLong_New()": use
    "PyLongWriter_Create()".

  * "_PyThreadState_UncheckedGet()": use
    "PyThreadState_GetUnchecked()".

  * "_PyUnicode_AsString()": use "PyUnicode_AsUTF8()".

  * "_PyUnicodeWriter_Init()": replace
    "_PyUnicodeWriter_Init(&writer)" with "writer =
    PyUnicodeWriter_Create(0)".

  * "_PyUnicodeWriter_Finish()": replace
    "_PyUnicodeWriter_Finish(&writer)" with
    "PyUnicodeWriter_Finish(writer)".

  * "_PyUnicodeWriter_Dealloc()": replace
    "_PyUnicodeWriter_Dealloc(&writer)" with
    "PyUnicodeWriter_Discard(writer)".

  * "_PyUnicodeWriter_WriteChar()": replace
    "_PyUnicodeWriter_WriteChar(&writer, ch)" with
    "PyUnicodeWriter_WriteChar(writer, ch)".

  * "_PyUnicodeWriter_WriteStr()": replace
    "_PyUnicodeWriter_WriteStr(&writer, str)" with
    "PyUnicodeWriter_WriteStr(writer, str)".

  * "_PyUnicodeWriter_WriteSubstring()": replace
    "_PyUnicodeWriter_WriteSubstring(&writer, str, start, end)" with
    "PyUnicodeWriter_WriteSubstring(writer, str, start, end)".

  * "_PyUnicodeWriter_WriteASCIIString()": replace
    "_PyUnicodeWriter_WriteASCIIString(&writer, str)" with
    "PyUnicodeWriter_WriteASCII(writer, str)".

  * "_PyUnicodeWriter_WriteLatin1String()": replace
    "_PyUnicodeWriter_WriteLatin1String(&writer, str)" with
    "PyUnicodeWriter_WriteUTF8(writer, str)".

  * "_PyUnicodeWriter_Prepare()": (no replacement).

  * "_PyUnicodeWriter_PrepareKind()": (no replacement).

  * "_Py_HashPointer()": use "Py_HashPointer()".

  * "_Py_fopen_obj()": use "Py_fopen()".

  The pythoncapi-compat project can be used to get these new public
  functions on Python 3.13 and older. (Contributed by Victor Stinner
  in gh-128863.)


Pending removal in future versions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

* "Py_TPFLAGS_HAVE_FINALIZE": Unneeded since Python 3.8.

* "PyErr_Fetch()": Use "PyErr_GetRaisedException()" instead.

* "PyErr_NormalizeException()": Use "PyErr_GetRaisedException()"
  instead.

* "PyErr_Restore()": Use "PyErr_SetRaisedException()" instead.

* "PyModule_GetFilename()": Use "PyModule_GetFilenameObject()"
  instead.

* "PyOS_AfterFork()": Use "PyOS_AfterFork_Child()" instead.

* "PySlice_GetIndicesEx()": Use "PySlice_Unpack()" and
  "PySlice_AdjustIndices()" instead.

* "PyUnicode_READY()": Unneeded since Python 3.12

* "PyErr_Display()": Use "PyErr_DisplayException()" instead.

* "_PyErr_ChainExceptions()": Use "_PyErr_ChainExceptions1()" instead.

* "PyBytesObject.ob_shash" member: call "PyObject_Hash()" instead.

* Thread Local Storage (TLS) API:

  * "PyThread_create_key()": Use "PyThread_tss_alloc()" instead.

  * "PyThread_delete_key()": Use "PyThread_tss_free()" instead.

  * "PyThread_set_key_value()": Use "PyThread_tss_set()" instead.

  * "PyThread_get_key_value()": Use "PyThread_tss_get()" instead.

  * "PyThread_delete_key_value()": Use "PyThread_tss_delete()"
    instead.

  * "PyThread_ReInitTLS()": Unneeded since Python 3.7.


Build Changes
=============

* "arm64-apple-ios" and "arm64-apple-ios-simulator" are both now **PEP
  11** tier 3 platforms. (PEP 730 written and implementation
  contributed by Russell Keith-Magee in gh-114099.)

* "aarch64-linux-android" and "x86_64-linux-android" are both now
  **PEP 11** tier 3 platforms. (PEP 738 written and implementation
  contributed by Malcolm Smith in gh-116622.)

* "wasm32-wasi" is now a **PEP 11** tier 2 platform. (Contributed by
  Brett Cannon in gh-115192.)

* "wasm32-emscripten" is no longer a **PEP 11** supported platform.
  (Contributed by Brett Cannon in gh-115192.)

* Building CPython now requires a compiler with support for the C11
  atomic library, GCC built-in atomic functions, or MSVC interlocked
  intrinsics.

* Autoconf 2.71 and aclocal 1.16.5 are now required to regenerate the
  "configure" script. (Contributed by Christian Heimes in gh-89886 and
  by Victor Stinner in gh-112090.)

* SQLite 3.15.2 or newer is required to build the "sqlite3" extension
  module. (Contributed by Erlend Aasland in gh-105875.)

* CPython now bundles the mimalloc library by default. It is licensed
  under the MIT license; see mimalloc license. The bundled mimalloc
  has custom changes, see gh-113141 for details. (Contributed by Dino
  Viehland in gh-109914.)

* The "configure" option "--with-system-libmpdec" now defaults to
  "yes". The bundled copy of "libmpdec" will be removed in Python
  3.16.

* Python built with "configure" "--with-trace-refs" (tracing
  references) is now ABI compatible with the Python release build and
  debug build. (Contributed by Victor Stinner in gh-108634.)

* On POSIX systems, the pkg-config (".pc") filenames now include the
  ABI flags.  For example, the free-threaded build generates
  "python-3.13t.pc" and the debug build generates "python-3.13d.pc".

* The "errno", "fcntl", "grp", "md5", "pwd", "resource", "termios",
  "winsound", "_ctypes_test", "_multiprocessing.posixshmem",
  "_scproxy", "_stat", "_statistics", "_testconsole",
  "_testimportmultiple" and "_uuid" C extensions are now built with
  the limited C API. (Contributed by Victor Stinner in gh-85283.)


Porting to Python 3.13
======================

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


Changes in the Python API
-------------------------

* PEP 667 introduces several changes to the semantics of "locals()"
  and "f_locals":

  * Calling "locals()" in an *optimized scope* now produces an
    independent snapshot on each call, and hence no longer implicitly
    updates previously returned references. Obtaining the legacy
    CPython behavior now requires explicit calls to update the
    initially returned dictionary with the results of subsequent calls
    to "locals()". Code execution functions that implicitly target
    "locals()" (such as "exec" and "eval") must be passed an explicit
    namespace to access their results in an optimized scope. (Changed
    as part of **PEP 667**.)

  * Calling "locals()" from a comprehension at module or class scope
    (including via "exec" or "eval") once more behaves as if the
    comprehension were running as an independent nested function (i.e.
    the local variables from the containing scope are not included).
    In Python 3.12, this had changed to include the local variables
    from the containing scope when implementing **PEP 709**. (Changed
    as part of **PEP 667**.)

  * Accessing "FrameType.f_locals" in an *optimized scope* now returns
    a write-through proxy rather than a snapshot that gets updated at
    ill-specified times. If a snapshot is desired, it must be created
    explicitly with "dict" or the proxy's ".copy()" method. (Changed
    as part of **PEP 667**.)

* "functools.partial" now emits a "FutureWarning" when used as a
  method. The behavior will change in future Python versions. Wrap it
  in "staticmethod()" if you want to preserve the old behavior.
  (Contributed by Serhiy Storchaka in gh-121027.)

* An "OSError" is now raised by "getpass.getuser()" for any failure to
  retrieve a username, instead of "ImportError" on non-Unix platforms
  or "KeyError" on Unix platforms where the password database is
  empty.

* The value of the "mode" attribute of "gzip.GzipFile" is now a string
  ("'rb'" or "'wb'") instead of an integer ("1" or "2"). The value of
  the "mode" attribute of the readable file-like object returned by
  "zipfile.ZipFile.open()" is now "'rb'" instead of "'r'".
  (Contributed by Serhiy Storchaka in gh-115961.)

* "mailbox.Maildir" now ignores files with a leading dot (".").
  (Contributed by Zackery Spytz in gh-65559.)

* "pathlib.Path.glob()" and "rglob()" now return both files and
  directories if a pattern that ends with ""**"" is given, rather than
  directories only. Add a trailing slash to keep the previous behavior
  and only match directories.

* The "threading" module now expects the "_thread" module to have an
  "_is_main_interpreter()" function. This function takes no arguments
  and returns "True" if the current interpreter is the main
  interpreter.

  Any library or application that provides a custom "_thread" module
  must provide "_is_main_interpreter()", just like the module's other
  "private" attributes. (gh-112826.)


Changes in the C API
--------------------

* "Python.h" no longer includes the "<ieeefp.h>" standard header. It
  was included for the "finite()" function which is now provided by
  the "<math.h>" header. It should now be included explicitly if
  needed. Remove also the "HAVE_IEEEFP_H" macro. (Contributed by
  Victor Stinner in gh-108765.)

* "Python.h" no longer includes these standard header files:
  "<time.h>", "<sys/select.h>" and "<sys/time.h>". If needed, they
  should now be included explicitly. For example, "<time.h>" provides
  the "clock()" and "gmtime()" functions, "<sys/select.h>" provides
  the "select()" function, and "<sys/time.h>" provides the
  "futimes()", "gettimeofday()" and "setitimer()" functions.
  (Contributed by Victor Stinner in gh-108765.)

* On Windows, "Python.h" no longer includes the "<stddef.h>" standard
  header file. If needed, it should now be included explicitly. For
  example, it provides "offsetof()" function, and "size_t" and
  "ptrdiff_t" types. Including "<stddef.h>" explicitly was already
  needed by all other platforms, the "HAVE_STDDEF_H" macro is only
  defined on Windows. (Contributed by Victor Stinner in gh-108765.)

* If the "Py_LIMITED_API" macro is defined, "Py_BUILD_CORE",
  "Py_BUILD_CORE_BUILTIN" and "Py_BUILD_CORE_MODULE" macros are now
  undefined by "<Python.h>". (Contributed by Victor Stinner in
  gh-85283.)

* The old trashcan macros "Py_TRASHCAN_SAFE_BEGIN" and
  "Py_TRASHCAN_SAFE_END" were removed. They should be replaced by the
  new macros "Py_TRASHCAN_BEGIN" and "Py_TRASHCAN_END".

  A "tp_dealloc" function that has the old macros, such as:

     static void
     mytype_dealloc(mytype *p)
     {
         PyObject_GC_UnTrack(p);
         Py_TRASHCAN_SAFE_BEGIN(p);
         ...
         Py_TRASHCAN_SAFE_END
     }

  should migrate to the new macros as follows:

     static void
     mytype_dealloc(mytype *p)
     {
         PyObject_GC_UnTrack(p);
         Py_TRASHCAN_BEGIN(p, mytype_dealloc)
         ...
         Py_TRASHCAN_END
     }

  Note that "Py_TRASHCAN_BEGIN" has a second argument which should be
  the deallocation function it is in. The new macros were added in
  Python 3.8 and the old macros were deprecated in Python 3.11.
  (Contributed by Irit Katriel in gh-105111.)

* PEP 667 introduces several changes to frame-related functions:

  * The effects of mutating the dictionary returned from
    "PyEval_GetLocals()" in an *optimized scope* have changed. New
    dict entries added this way will now *only* be visible to
    subsequent "PyEval_GetLocals()" calls in that frame, as
    "PyFrame_GetLocals()", "locals()", and "FrameType.f_locals" no
    longer access the same underlying cached dictionary. Changes made
    to entries for actual variable names and names added via the
    write-through proxy interfaces will be overwritten on subsequent
    calls to "PyEval_GetLocals()" in that frame. The recommended code
    update depends on how the function was being used, so refer to the
    deprecation notice on the function for details.

  * Calling "PyFrame_GetLocals()" in an *optimized scope* now returns
    a write-through proxy rather than a snapshot that gets updated at
    ill-specified times. If a snapshot is desired, it must be created
    explicitly (e.g. with "PyDict_Copy()"), or by calling the new
    "PyEval_GetFrameLocals()" API.

  * "PyFrame_FastToLocals()" and "PyFrame_FastToLocalsWithError()" no
    longer have any effect. Calling these functions has been redundant
    since Python 3.11, when "PyFrame_GetLocals()" was first
    introduced.

  * "PyFrame_LocalsToFast()" no longer has any effect. Calling this
    function is redundant now that "PyFrame_GetLocals()" returns a
    write-through proxy for *optimized scopes*.

* Python 3.13 removed many private functions. Some of them can be
  replaced using these alternatives:

  * "_PyDict_Pop()": "PyDict_Pop()" or "PyDict_PopString()";

  * "_PyDict_GetItemWithError()": "PyDict_GetItemRef()";

  * "_PyErr_WriteUnraisableMsg()":  "PyErr_FormatUnraisable()";

  * "_PyEval_SetTrace()": "PyEval_SetTrace()" or
    "PyEval_SetTraceAllThreads()";

  * "_PyList_Extend()": "PyList_Extend()";

  * "_PyLong_AsInt()": "PyLong_AsInt()";

  * "_PyMem_RawStrdup()": "strdup()";

  * "_PyMem_Strdup()": "strdup()";

  * "_PyObject_ClearManagedDict()": "PyObject_ClearManagedDict()";

  * "_PyObject_VisitManagedDict()": "PyObject_VisitManagedDict()";

  * "_PyThreadState_UncheckedGet()": "PyThreadState_GetUnchecked()";

  * "_PyTime_AsSecondsDouble()": "PyTime_AsSecondsDouble()";

  * "_PyTime_GetMonotonicClock()": "PyTime_Monotonic()" or
    "PyTime_MonotonicRaw()";

  * "_PyTime_GetPerfCounter()": "PyTime_PerfCounter()" or
    "PyTime_PerfCounterRaw()";

  * "_PyTime_GetSystemClock()": "PyTime_Time()" or "PyTime_TimeRaw()";

  * "_PyTime_MAX": "PyTime_MAX";

  * "_PyTime_MIN": "PyTime_MIN";

  * "_PyTime_t": "PyTime_t";

  * "_Py_HashPointer()": "Py_HashPointer()";

  * "_Py_IsFinalizing()": "Py_IsFinalizing()".

  The pythoncapi-compat project can be used to get most of these new
  functions on Python 3.12 and older.


Regression Test Changes
=======================

* Python built with "configure" "--with-pydebug" now supports a "-X
  presite=package.module" command-line option. If used, it specifies a
  module that should be imported early in the lifecycle of the
  interpreter, before "site.py" is executed. (Contributed by Łukasz
  Langa in gh-110769.)
