[Carl] >> Currently you only get results that violate arithmetic identities if you >> mix arithmetic within a timezone and arithmetic between timezones. [Tim] > And we currently have timeline conversions that can violate basic > identities in _that_ space. It is trading one for the other.
Yes. The new proposed behavior for PEP 495 abandons the assertion that it can be "independent of arithmetic", recognizing that instead we're trading consistency of arithmetic within a timezone for consistency of round-trips between timezones. So PEP 495 is already breaking the design of datetime, that tz-annotated datetimes operate internally on a naive time model. It _has_ to break that design, because it must introduce times that don't exist in that model. But it's choosing to change that design piecemeal and inconsistently instead of thoroughly and consistently. Carl
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Datetime-SIG mailing list [email protected] https://mail.python.org/mailman/listinfo/datetime-sig The PSF Code of Conduct applies to this mailing list: https://www.python.org/psf/codeofconduct/
