What’s New In Python 3.13

Release:

3.13.0a0

Date:

July 03, 2023

This article explains the new features in Python 3.13, compared to 3.12.

For full details, see the changelog.

Note

Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.13 moves towards release, so it’s worth checking back even after reading earlier versions.

Summary – Release highlights

New Features

Other Language Changes

New Modules

• None yet.

Improved Modules

array

• Add 'w' type code that can be used for Unicode strings. It can be used instead of 'u' type code, which is deprecated. (Contributed by Inada Naoki in gh-80480.)

io

The io.IOBase finalizer now logs the close() method errors with sys.unraisablehook. Previously, errors were ignored silently by default, and only logged in Python Development Mode or on Python built on debug mode. (Contributed by Victor Stinner in gh-62948.)

pathlib

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

• Add support for recursive wildcards in pathlib.PurePath.match(). (Contributed by Barney Gale in gh-73435.)

• Add follow_symlinks keyword-only argument to pathlib.Path.glob(), rglob(), is_file(), and is_dir(). (Contributed by Barney Gale in gh-77609 and gh-105793.)

traceback

• Add show_group paramter to traceback.TracebackException.format_exception_only() to format the nested exceptions of a BaseExceptionGroup instance, recursively. (Contributed by Irit Katriel in gh-105292.)

typing

• Add typing.get_protocol_members() to return the set of members defining a typing.Protocol. Add typing.is_protocol() to check whether a class is a typing.Protocol. (Contributed by Jelle Zijlstra in gh-104873.)

Optimizations

Deprecated

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

• Creating a typing.NamedTuple class using keyword arguments to denote the fields (NT = NamedTuple("NT", x=int, y=int)) is deprecated, and will be disallowed in Python 3.15. Use the class-based syntax or the functional syntax instead. (Contributed by Alex Waygood in gh-105566.)

• When using the functional syntax to create a typing.NamedTuple class or a typing.TypedDict class, failing to pass a value to the ‘fields’ parameter (NT = NamedTuple("NT") or TD = TypedDict("TD")) is deprecated. Passing None to the ‘fields’ parameter (NT = NamedTuple("NT", None) or TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []). To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}). (Contributed by Alex Waygood in gh-105566 and gh-105570.)

• array’s 'u' format code, deprecated in docs since Python 3.3, emits DeprecationWarning since 3.13 and will be removed in Python 3.16. Use the 'w' format code instead. (contributed by Hugo van Kemenade in gh-80480)

• ctypes: Deprecate undocumented ctypes.SetPointerType() and ctypes.ARRAY() functions. Replace ctypes.SetPointerType(item_type, size) with item_type * size. (Contributed by Victor Stinner in gh-105733.)

Removed

• PEP 594: Remove the telnetlib module, deprecated in Python 3.11: use the projects telnetlib3 or Exscript instead. (Contributed by Victor Stinner in gh-104773.)

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

• Namespaces typing.io and typing.re, deprecated in Python 3.8, are now removed. The items in those namespaces can be imported directly from typing. (Contributed by Sebastian Rittau in gh-92871.)

• Remove the untested and undocumented webbrowser 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 support for using pathlib.Path objects as context managers. This functionality was deprecated and made a no-op in Python 3.9.

• Remove the undocumented configparser.LegacyInterpolation class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in gh-104886.)

• Remove the turtle.RawTurtle.settiltangle() method, deprecated in docs since Python 3.1 and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in gh-104876.)

• Removed the following unittest functions, deprecated in Python 3.11:

  • unittest.findTestCases()

  • unittest.makeSuite()

  • unittest.getTestCaseNames()

  Use TestLoader methods instead:

  • unittest.TestLoader.loadTestsFromModule()

  • unittest.TestLoader.loadTestsFromTestCase()

  • unittest.TestLoader.getTestCaseNames()

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

• PEP 594: Remove the cgi and cgitb modules, deprecated in Python 3.11.

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

  • cgi.parse() can be replaced by calling urllib.parse.parse_qs() directly on the desired query string, except for multipart/form-data input, which can be handled as described for cgi.parse_multipart().

  • cgi.parse_multipart() can be replaced with the functionality in the email package (e.g. email.message.EmailMessage and email.message.Message) which implements the same MIME RFCs, or with the multipart PyPI project.

  • 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
    

  (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the sndhdr module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the pipes module, deprecated in Python 3.11: use the subprocess module instead. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the ossaudiodev module, deprecated in Python 3.11: use the pygame project for audio playback. (Contributed by Victor Stinner in gh-104780.)

• PEP 594: Remove the sunau module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the mailcap module, deprecated in Python 3.11. The mimetypes module provides an alternative. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the spwd module, deprecated in Python 3.11: the python-pam project can be used instead. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the nntplib module, deprecated in Python 3.11: the PyPI nntplib project can be used instead. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the nis module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the xdrlib module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the msilib module, deprecated in Python 3.11. (Contributed by Zachary Ware in gh-104773.)

• PEP 594: Remove the crypt module and its private _crypt extension, deprecated in Python 3.11. The hashlib module is a potential replacement for certain use cases. Otherwise, the following PyPI projects can be used:

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

  • passlib: Comprehensive password hashing framework supporting over 30 schemes.

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

  • legacycrypt: Wrapper to the POSIX crypt library call and associated functionality.

  (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the uu module, deprecated in Python 3.11: the base64 module is a modern alternative. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the aifc module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the audioop module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

• PEP 594: Remove the chunk module, deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104773.)

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

• PEP 594: Remove the imghdr module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in gh-104773.)

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

• 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.)

• Remove the old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END. 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.)

• Remove locale.resetlocale() function deprecated in Python 3.11: use locale.setlocale(locale.LC_ALL, "") instead. (Contributed by Victor Stinner in gh-104783.)

• Remove the undocumented and untested logging.Logger.warn() method, deprecated since Python 3.3, which was an alias to the logging.Logger.warning() method: use the logging.Logger.warning() method instead. (Contributed by Victor Stinner in gh-105376.)

• Remove cafile, capath and cadefault parameters of the urllib.request.urlopen() function, deprecated in Python 3.6: use the context parameter instead. Please use ssl.SSLContext.load_cert_chain() instead, or let ssl.create_default_context() select the system’s trusted CA certificates for you. (Contributed by Victor Stinner in gh-105382.)

• Remove deprecated webbrowser.MacOSXOSAScript._name attribute. Use webbrowser.MacOSXOSAScript.name attribute instead. (Contributed by Nikita Sobolev in gh-105546.)

• Remove undocumented, never working, and deprecated re.template function and re.TEMPLATE flag (and re.T alias). (Contributed by Serhiy Storchaka and Nikita Sobolev in gh-105687.)

Porting to Python 3.13

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

• 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.

Build Changes

• Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate !configure. (Contributed by Christian Heimes in gh-89886.)

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

C API Changes

New Features

• 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.)

• Add PyImport_AddModuleRef(): similar to PyImport_AddModule(), but return a strong reference instead of a borrowed reference. (Contributed by Victor Stinner in gh-105922.)

• Add PyWeakref_GetRef() function: similar to PyWeakref_GetObject() but returns a strong reference, or NULL if the referent is no longer live. (Contributed by Victor Stinner in gh-105927.)

• 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. If the assertion fails, make sure that the size is set before. (Contributed by Victor Stinner in gh-106168.)

Porting to Python 3.13

Deprecated

• Deprecate the old Py_UNICODE and PY_UNICODE_TYPE types: use directly the wchar_t type 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 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 PYTHONHOME environment variable instead.

  (Contributed by Victor Stinner in gh-105145.)

• Deprecate the PyImport_ImportModuleNoBlock() function which is just an alias to PyImport_ImportModule() since Python 3.3. Scheduled for removal in Python 3.15. (Contributed by Victor Stinner in gh-105396.)

• Deprecate the PyWeakref_GetObject() and PyWeakref_GET_OBJECT() functions, which return a borrowed reference: use the new PyWeakref_GetRef() function instead, it 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.)

Removed

• Remove functions deprecated in Python 3.9.

  • PyEval_CallObject(), PyEval_CallObjectWithKeywords(): use PyObject_CallNoArgs() or PyObject_Call() instead. Warning: PyObject_Call() positional arguments must be a tuple and must not be NULL, keyword arguments must be a dict or NULL, whereas removed functions checked arguments type 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 old buffer protocols deprecated in Python 3.0. Use Buffer Protocol instead.

  • PyObject_CheckReadBuffer(): Use PyObject_CheckBuffer() to test if 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(): 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 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_SetArgvEx(): set PyConfig.argv instead.

  • PySys_SetArgv(): set PyConfig.argv instead.

  • PySys_SetPath(): set PyConfig.module_search_paths instead.

  • Py_SetPath(): set PyConfig.module_search_paths instead.

  • Py_SetProgramName(): set PyConfig.program_name instead.

  • Py_SetPythonHome(): set PyConfig.home instead.

  • Py_SetStandardStreamEncoding(): set PyConfig.stdio_encoding instead.

  • _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_InitThreads() and PyEval_ThreadsInitialized() functions, deprecated in Python 3.9. Since Python 3.7, Py_Initialize() always creates the GIL: calling PyEval_InitThreads() did nothing and PyEval_ThreadsInitialized() always returned non-zero. (Contributed by Victor Stinner in gh-105182.)

• 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 old private, undocumented and untested _PyGC_FINALIZED() macro which was kept for backward compatibility with Python 3.8 and older: use PyObject_GC_IsFinalized() instead. The pythoncapi-compat project can be used to get this function on Python 3.8 and older. (Contributed by Victor Stinner in gh-105268.)

• Remove the old aliases to functions calling functions which were kept for backward compatibility with Python 3.8 provisional API:

  • _PyObject_CallMethodNoArgs(): use PyObject_CallMethodNoArgs()

  • _PyObject_CallMethodOneArg(): use PyObject_CallMethodOneArg()

  • _PyObject_CallOneArg(): use PyObject_CallOneArg()

  • _PyObject_FastCallDict(): use PyObject_VectorcallDict()

  • _PyObject_Vectorcall(): use PyObject_Vectorcall()

  • _PyObject_VectorcallMethod(): use PyObject_VectorcallMethod()

  • _PyVectorcall_Function(): use PyVectorcall_Function()

  Just remove the underscore prefix to update your code. (Contributed by Victor Stinner in gh-106084.)

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

• Remove cpython/pytime.h header file: it only contained private functions. (Contributed by Victor Stinner in gh-106316.)

• Remove _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.)