Question

Is there a way I can obtain a datetime aware object out of a string in Python using only the standard library modules ?

I know that I can use dateutil.parser.parse, but unfortunately that’s not a good enough reason to add it as a dependency to my project. I already have the mx.DateTime module as a dependency, buuttttt:

>>> dateutil.parser.parse('2011-10-24T06:51:47-07:00')
datetime.datetime(2011, 10, 24, 6, 51, 47, tzinfo=tzoffset(None, -25200))

>>> mx.DateTime.ISO.ParseDateTimeUTC('2011-10-24T06:51:47-07:00')
<mx.DateTime.DateTime object for '2011-10-24 13:51:47.00' at 29c7e48>

the ParseDateTimeUTC fails to detect the offset, even though in its documentation says that:

Returns a DateTime instance in UTC reflecting the given ISO
date. A time part is optional and must be delimited from the
date by a space or 'T'. Timezones are honored.

Answer 1

mx.DateTime.ISO.ParseDateTimeUTC is doing the right thing – it is applying the specified timezone to adjust the time to UTC. The resulting UTC time doesn’t have a timezone because it isn’t a local time anymore.

The standard Python library doesn’t contain any concrete timezone classes according to the documentation:

tzinfo is an abstract base clase, meaning that this class should not
be instantiated directly. You need to derive a concrete subclass, and
(at least) supply implementations of the standard tzinfo methods
needed by the datetime methods you use. The datetime module does not
supply any concrete subclasses of tzinfo.

I’ve always been surprised that they didn’t at least include a class for UTC, or a generic implementation like dateutil’s tzoffset.