Carl Meyer <c...@oddbird.net> added the comment: Good idea to check with the PEP authors.
I don’t think allowing both ClassVar and Final in dataclasses requires general intersection types. Neither ClassVar nor Final are real types; they aren’t part of the type of the value. They are more like special annotations on a name, which are wrapped around a type as syntactic convenience. You’re right that it would require more than just amendment to the PEP text, though; it might require changes to type checkers, and it would also require changes to the runtime behavior of the `typing` module to special-case allowing `ClassVar[Final[…]]`. And the downside of this change is that it couldn’t be context sensitive to only be allowed in dataclasses. But I think this isn’t a big problem; type checkers could still error on that wrapping in non dataclass contexts if they want to. But even if that change can’t be made, I think backwards compatibility still precludes changing the interpretation of `x: Final[int] = 3` on a dataclass, and it is more valuable to be able to specify Final instance attributes (fields) than final class attributes on dataclasses. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue45384> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
