Schedule removal for deprecated `abc` decorators

[aiwonderland]

Proposal:

Remove deprecated abc.abstractclassmethod, abc.abstractstaticmethod and abc.abstractproperty for 3.16.
or maybe and an warn:

import warnings
# codes ...
class abstractproperty(property):
    __isabstractmethod__ = True

    def __init__(self, fget=None, fset=None, fdel=None, doc=None):
        warnings.warn(
            "abc.abstractproperty is deprecated and will be removed in Python 3.16. "
            "Use @property with @abstractmethod instead.",
            FutureWarning,
            stacklevel=2
        )
        super().__init__(fget, fset, fdel, doc)

Linked PRs

• gh-149609: Raise deprecation warnings for abc.{abstractclassmethod,abstractstaticmethod,abstractproperty} #149636

[picnixz]

I really want those methods to be gone. It's annoying that they are sometimes suggested by my IDE!

[picnixz]

Oh wait, there was no warning? so no we can't remove them sorry.

[picnixz]

They've been deprecated since 3.3. If we plan to deprecate them (warning+removal) we need a 5y period first now.

[picnixz]

cc @JelleZijlstra @sobolevn @hugovk @rhettinger

[aiwonderland]

thanks 👍

[JelleZijlstra]

I haven't worked on the abc module at all, but my general view is that removing things is always costly as it can break libraries and make it harder for people to upgrade. These functions are marked as @deprecated in typeshed, so IDEs should already avoid suggesting them.

[picnixz]

Unfortunately, they are still allowed in the suggestion list, but I guess it's more a problem for the IDE to solve. Do we have a policy on adding runtime warnings for deprecated functions actually? because those functions were only deprecated in docs.

[hugovk]

Yes, PEP 387.

If we want to remove them, we need runtime warnings first. ("For changes that are unable to raise a deprecation warning, consult with the steering council.")

Warnings should be raised for a minimum of two feature releases, but five years is preferred:

3. Wait for the warning to appear in at least two minor Python versions of the same major version, or one minor version in an older major version (e.g., for a warning in Python 3.10.0, you either wait until at least Python 3.12 or Python 4.0 to make the change). It is preferred, though, to wait 5 years before removal (e.g., warn starting in Python 3.10, removal in 3.15; this happens to coincide with the current lifetime of a minor release of Python).

https://peps.python.org/pep-0387/#making-incompatible-changes