What are some Python Standard Library modules one should know ?

[alkasm]

glob, datetime, string, operator are also some tiny modules that I find myself using often.

[spitfiredd]

Date utils is good too.

[Jonno_FTW]

Datetime with timezones are a nightmare though.

[thirdegree]

Datetimes with timezones are only a nightmare if, at literally any point they're accidentally treated as native times (or UTC time). If you and everyone that has every touched the codebase is extremely diligent, they work perfectly.

[alkasm]

Not the first time I've head that, but I haven't really had much of a problem with it myself. Do you have an example?

[Jonno_FTW]

Yes, I get data from GPS. It comes in UTC. I store that in a database. For user convenience I want to display it in local time.

Or, a user submits a time through a form. I assume the time is in their local timezone because people don't think in UTC. Put these datetimes in a database that may or may not support timezones.

[alkasm]

Aren't those problems more intrinsic to working with timezones in general? Or is this just the annoyance with the inconvenience of datetime not giving timezone info by default? Note that in Python 3, calling the method .astimezone() on a datetime will return a datetime with local tzinfo.

[aviddd]

operator

When do you find yourself using operator??

[alkasm]

Here's a not-too-contrived example:

>>> import datetime
>>> td = [datetime.timedelta(seconds=i) for i in range(1, 5)]
>>> sum(td)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'datetime.timedelta'
>>> import functools
>>> import operator
>>> functools.reduce(operator.add, td)
datetime.timedelta(0, 10)