There seems to be no way to transparently make an abstract base class enforce instance attributes for subclasses (without creating a custom metaclass, see e.g. https://newbedev.com/python-abstract-class-shall-force-derived-classes-to-initialize-variable-in-init).

The analogous problem for enforcing *class* attributes in subclasses can be solved by creating an abstract class property (which can then be overridden by a class attribute), but this feels like a hack and possibly a bug (see https://bugs.python.org/issue44904 for a related bug).

The corresponding "solution" for instance attributes does not work (see attached file), and probably rightly so.

This seems like an oversight to me.