Pending removal in Python 3.16

Pending removal in Python 3.16

• The import system:

  • Setting :attr:~module.__loader__ on a module while failing to set :attr:__spec__.loader <importlib.machinery.ModuleSpec.loader> is deprecated. In Python 3.16, :attr:!__loader__ will cease to be set or taken into consideration by the import system or the standard library.

• :mod:array:

  • The 'u' format code (:c:type:wchar_t) has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use the 'w' format code (:c:type:Py_UCS4) for Unicode characters instead.

• :mod:asyncio:

  • :func:!asyncio.iscoroutinefunction is deprecated and will be removed in Python 3.16; use :func:inspect.iscoroutinefunction instead. (Contributed by Jiahao Li and Kumar Aditya in :gh:122875.)

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

    • :class:asyncio.AbstractEventLoopPolicy
    • :class:asyncio.DefaultEventLoopPolicy
    • :class:asyncio.WindowsSelectorEventLoopPolicy
    • :class:asyncio.WindowsProactorEventLoopPolicy
    • :func:asyncio.get_event_loop_policy
    • :func:asyncio.set_event_loop_policy

    Users should use :func:asyncio.run or :class:asyncio.Runner with loop_factory to use the desired event loop implementation.

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

    import asyncio

    async def main(): ...

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

    (Contributed by Kumar Aditya in :gh:127949.)

• :mod: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)).

• :mod:functools:

  • Calling the Python implementation of :func:functools.reduce with function or sequence as keyword arguments has been deprecated since Python 3.14.

• :mod: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.)

• :mod:mimetypes:

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

• :mod:shutil:

  • The :class:!ExecError exception has been deprecated since Python 3.14. It has not been used by any function in :mod:!shutil since Python 3.4, and is now an alias of :exc:RuntimeError.

• :mod:symtable:

  • The :meth:Class.get_methods <symtable.Class.get_methods> method has been deprecated since Python 3.14.

• :mod:sys:

  • The :func:~sys._enablelegacywindowsfsencoding function has been deprecated since Python 3.13. Use the :envvar:PYTHONLEGACYWINDOWSFSENCODING environment variable instead.

• :mod:sysconfig:

  • The :func:!sysconfig.expand_makefile_vars function has been deprecated since Python 3.14. Use the vars argument of :func:sysconfig.get_paths instead.

• :mod:tarfile:

  • The undocumented and unused :attr:!TarFile.tarfile attribute has been deprecated since Python 3.13.