Question

Why can’t subtract two time objects? For example, 12:00 – 11:00 = 1:00

from datetime import time
time(12,00) - time(11,00) # -> timedelta(hours=1)

It seems that datetime.time.__sub__ is missing

TypeError: unsupported operand type(s) for -: 'datetime.time' and 'datetime.time'

do you know why?

Answer 1

The time objects have no date, so for example, the 12:00 might be (say) on a Wed and the 11:00 on the preceding Tue, making the difference 25 hours, not one (any multiple of 24 might be added or subtracted). If you know they’re actually on the same date, just apply any arbitrary date to each of them (making two datetime objects) and then you’ll be able to subtract them. E.g.:

import datetime

def timediff(t1, t2):
  td = datetime.date.today()
  return datetime.datetime.combine(td, t1) - datetime.datetime.combine(td, t2)