2020-12-13 Alan E. Davis wrote:
I think R would not be too unwieldy as a hammer here. My use case is a humble one: just take a several clock times in HH:MM format (utc) and adjust to another timezone by adding or subtracting the relevant number of hours. The day of week is not important; i will have to deal with it. I did imagine a conditional subtraction by adding of subtracting 24:00 as needed.
Likely your approach is suitable for you and you could ignore my comments. I just live in a city having longitude that should be (and it was) the border between time zones, so majority do not like any decision. Since cancellation of DST 10 years ago, local time has been shifted 2 times...
To get time offset for some timezone, it is necessary to specify timestamp, so a date is required in addition to time. Namely day of week is mostly irrelevant.
Time transitions are usually arranged at night when most of people are not active. Astronomers is a different case, that is why their chance to face a timezone bug is higher.
When operations with arbitrary time zones are not required and a process could be run with TZ variable set to desired time zone, libc functions should work correctly. I have not tried elisp functions https://www.gnu.org/software/emacs/manual/html_node/elisp/Time-Zone-Rules.html
A bookmark for those who still hopes to avoid complications with time-related operations
Falsehoods programmers believe about time https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time
