Comment by welder
7 years ago
Yes, I forgot to make an exception for scheduling future local times, so use utc except for future local datetimes.
7 years ago
Yes, I forgot to make an exception for scheduling future local times, so use utc except for future local datetimes.
I didn't downvote any of your comments but "In this case [...] store the time zone string" -- seems to contradict your earlier advice of "Always use UTC without time zone".
The issue is that there are 2 types of future times:
(1) scientific-absolute times -- like future solar eclipses; you can normalize these types of times to a future UTC with no ambiguity (other than esoteric adjustments such as TAI leap seconds)
(2) cultural-relative-wall-clock times -- like future recurring appointments, future New Year's midnight celebrations, etc.; These can't be normalized to UTC perfectly because one doesn't know what the exact future UTC time will be due to unknown government changes to DST rules or TZ boundaries. If you simply normalize to UTC, you will throw away information and it will cause bugs. Your eventual addendum of "store the time zone string" basically acknowledges this edge case for future datetimes.