True iff target itself is marked @RequiresSubclass().
Accepts either a class (constructor) or an instance, so callers don't have to normalize.
Uses an OWN-property check, so a subclass of a marked base returns false — only the class
that actually declared the marker is treated as non-instantiable.
Also honors the legacy static RequiresSubclass = true form (same own-property semantics)
so bases written before the decorator existed keep working. Prefer the decorator.
True iff
targetitself is marked@RequiresSubclass().Accepts either a class (constructor) or an instance, so callers don't have to normalize. Uses an OWN-property check, so a subclass of a marked base returns
false— only the class that actually declared the marker is treated as non-instantiable.Also honors the legacy
static RequiresSubclass = trueform (same own-property semantics) so bases written before the decorator existed keep working. Prefer the decorator.