Saaket Prakash <saak...@gmail.com> added the comment:
Treating Final as ClassVar by default may be fine, but it should not throw when using default_factory like ClassVar does. There are valid uses of Final with instance variable when one would want the value to be unchanged after the `__init__` runs but different instances can be initialized with different values that are generated by a default_factory. A quick search on github for this pattern gives this https://github.com/166MMX/hiro-python-library/blob/fb29e3247a8fe1b0f7dc4e68141cf7340a8dd0a5/src/arago/hiro/model/ws.py#L120 which will break if Final throws when using default_factory. PEP 591 says: Type checkers should infer a final attribute _that is initialized in a class body_ as being a class variable. When using default_factory the attribute is not initialized inside the class body but when the instance is initialized. So allowing instance level Final with default_factory will not be going against the PEP. ---------- nosy: +saaketp _______________________________________ 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
