Pending removal in Python 3.17

Pending removal in Python 3.17

• :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: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.)