Non-Pedantic Time

Python’s datetime module has many uses, but it has a difficulty: you can’t do any arithmetic with datetime.time. Only with datetime.datetime. Now, there are good reasons for this: “What time will it be, 24 hours from now” has a lot of corner cases, including daylight savings time, leap seconds, historical timezone changes, and so on. But sometimes you really do need the simple case. Sometimes the perfect is the enemy of the good. And that’s why you have this module. This module will allow you to cocoon yourself in the comforting illusion that, in 24 hours, it will be the same time as it is right now.

And what freedom this illusion gives you! You can add a datetime.timedelta object to an nptime object, and it works! It will cycle around 24 hours, like modular arithmetic. You can ask “what time comes 1 day and 36 minutes after 12:24 pm?” and it will let you know: 1:00 pm. How lovely!

>>> from nptime import nptime
>>> from datetime import timedelta, date, datetime
>>> afternoon = nptime(12, 24) + timedelta(days=1, minutes=36)
>>> afternoon
nptime(13, 0)
>>> str(afternoon)
'13:00:00'

Maybe we’re talking about the afternoon of Guido van Rossum’s birthday. Lucky, we can combine nptime objects with date objects:

>>> datetime.combine(date(1956, 1, 31), afternoon)
datetime.datetime(1956, 1, 31, 13, 0)

You can also ask “How long is it between 9:00 AM and 5:00 PM? It sure feels like a million years!”

>>> workday = nptime(hour=17) - nptime(hour=9)
>>> workday
datetime.timedelta(0, 28800)
>>> print(workday)
8:00:00

Nope, only 8 hours, how strange. Anyway, please use this module. It will be convenient. But don’t use it when talking about concrete time, time in a particular place, or anything like that. In fact, it doesn’t even notice datetime.tzinfo objects right now. Good luck.

Note

You can find the newest version at https://github.com/tgs/nptime . You can find online documentation at http://tgs.github.com/nptime/ . The package is available for download from PyPi: easy_install nptime. This software is licensed under the 3-clause BSD License.

class nptime.nptime

nptime - a non-pedantic time object

Inherits from datetime.time. You can’t do arithmetic with that class, but with nptime you can:

• Add a datetime.timedelta to an nptime (commutative),

  resulting in another nptime

• Subtract a timedelta from an nptime, resulting in an

  nptime

• Subtract an nptime from another nptime, resulting in a

  timedelta

You can use the class methods from_timedelta() and from_time() to construct an nptime from those datetime classes. You can use the to_timedelta() instance method to construct a timedelta from an nptime.

I can’t figure out a reason you’d want to add two times together without using timedelta objects, but if someone requests that, I’m happy to include it.

nptime is naive about time zones. I think this is the only way that makes sense, since days are only 24 hours long in an abstract sense. But if you want to see a different system, pull requests are welcome...

classmethod from_time(other)

Construct an nptime object from a datetime.time

Note

This ignores the datetime.tzinfo that may be part of the time object.

classmethod from_timedelta(other)

Construct an nptime object from a datetime.timedelta.

The timedelta is taken to be the amount of time since midnight.

to_timedelta()

Construct a timedelta object from an nptime. The timedelta gives the number of seconds (and microseconds) since midnight.