pending-removal-in-3.17.rst

Pending removal in Python 3.17

• :mod:`datetime`:

  • :meth:`~datetime.datetime.strptime` calls using a format string containing %e (day of month) without a year. This has been deprecated since Python 3.15. (Contributed by Stan Ulbrych in :gh:`70647`.)

• :mod:`collections.abc`:

  • :class:`collections.abc.ByteString` is scheduled for removal in Python 3.17.

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

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

    See :pep:`PEP 688 <688#current-options>` for more details. (Contributed by Shantanu Jain in :gh:`91896`.)

• :mod:`encodings`:

  • Passing non-ascii encoding names to :func:`encodings.normalize_encoding` is deprecated and scheduled for removal in Python 3.17. (Contributed by Stan Ulbrych in :gh:`136702`.)

• :mod:`webbrowser`:

  • :class:`!webbrowser.MacOSXOSAScript` is deprecated in favour of :class:`!webbrowser.MacOS`. (:gh:`137586`)

• :mod:`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 :func:`typing.get_origin` and :func:`typing.get_args` instead of relying on private implementation details.

  • :class:`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 :ref:`buffer protocol <bufferobjects>` at runtime. For use in type annotations, either use :class:`~collections.abc.Buffer` or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).

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

    See :pep:`PEP 688 <688#current-options>` for more details. (Contributed by Shantanu Jain in :gh:`91896`.)