Pending removal in Python 3.16

• The import system:
  • Setting ~module.__loader__ on a module while failing to set __spec__.loader <importlib.machinery.ModuleSpec.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.
  • Setting ~module.__package__ on a module while failing to set __spec__.parent <importlib.machinery.ModuleSpec.parent> is deprecated. In Python 3.16, !__package__ will cease to be taken into consideration by the import system or standard library. (97879)
• The bundled copy of libmpdec.
• 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 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 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 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 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 !symtable.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 !TarInfo.tarfile attribute has been deprecated since Python 3.13.