TZ and zoneinfo support

[AndreyNikiforov]

What is the correct way to convert datetime (utc) to [arbitrary] timezone? Looks like this lib supports neither zoneinfo module nor astimezone() method...

Example I would like to run in CircuitPython:

from datetime import timezone
LOS_ANGELES = ZoneInfo("America/Los_Angeles")
dt_utc = datetime(2020, 11, 1, 8, tzinfo=timezone.utc)

# Before the PDT -> PST transition
print(dt_utc.astimezone(LOS_ANGELES))

# After the PDT -> PST transition
print((dt_utc + timedelta(hours=1)).astimezone(LOS_ANGELES))

[FoamyGuy]

To the best of my knowledge the timezone support is limited. There is code in a test here that shows how to convert from the default UTC time into an arbitrary timezone:

Adafruit_CircuitPython_datetime/tests/test_datetime.py

Line 898 in 3381501

dt_utc = dt.replace(tzinfo=timezone(timedelta(hours=-4), "EDT"))

After doing so the tzinfo will be set on your object and if you call isoformat() it will output the timestamp with a timezone offset e.g. 2024-11-14T15:49:04-04:00

You could theoretically use timedelta with utcoffset to get the time in the specified timezone, but I do not believe we currently have any support for something more convenient like astimezone(). We would welcome a PR from anyone who wants to add more timezone support that matches cpython.

[mcmanigle]

Not only this, but I think tzinfo.fromutc doesn't work. At least, the ValueError: dt.tzinfo is not self on line 627 seems counterintuitive?