offset-aware datetime.datetime.time() does not keep timezone #100371

LarsKumbier · 2022-12-20T14:44:02Z

Bug report

An offset-aware datetime.datetime.time() result does not contain the timezone of the original object. This leads to problems when trying to compare them with offset-aware times:

>>> from datetime import datetime, time, timezone, timedelta
>>> x = datetime(2022, 12, 20, 0, 0, 0, tzinfo=timezone(timedelta(hours=5)))
>>> x.tzinfo  # fine: x contains a proper timezone (is offset-aware)
datetime.timezone(datetime.timedelta(seconds=18000))
>>> x.time()  # bug: x.time() is not offset-aware anymore...
datetime.time(0, 0)
>>> x.time().tzinfo # ...because it does NOT retain the timezone info...
>>> x.time() < time(tzinfo=timezone(timedelta(hours=-2))) # ...so it can NOT be compared with offset-aware times.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can't compare offset-naive and offset-aware times

I would have expected that

offset-naive datetime.datetime.time() returns an offset-naive time object, and
offset-aware datetime.datetime.time() returns an offset-aware time object,

because with the current (faulty) behavior, we loose important specificity.

Your environment

CPython versions tested on: 3.10, 3.11
Operating system and architecture: Linux amd64

LarsKumbier · 2022-12-20T15:10:51Z

>>> help(x.time)
Help on built-in function time:

time(...) method of datetime.datetime instance
    Return time object with same time but with tzinfo=None.
>>> help(x.timetz)
Help on built-in function timetz:

timetz(...) method of datetime.datetime instance
    Return time object with same time and tzinfo.

Okay, there's an explicit method to get the tz-aware time. I would not have designed it like this (explicit is better than implicit and an implicit change of an offset-aware time into offset-naive feels wrong), but my problem is solved.

LarsKumbier added the type-bug An unexpected behavior, bug, or error label Dec 20, 2022

LarsKumbier closed this as completed Dec 20, 2022

Nov	DEC	Jan
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2021	2022	2023

offset-aware datetime.datetime.time() does not keep timezone #100371

offset-aware datetime.datetime.time() does not keep timezone #100371

LarsKumbier commented Dec 20, 2022

LarsKumbier commented Dec 20, 2022

offset-aware datetime.datetime.time() does not keep timezone #100371

offset-aware datetime.datetime.time() does not keep timezone #100371

Comments

LarsKumbier commented Dec 20, 2022

Bug report

Your environment

LarsKumbier commented Dec 20, 2022