call function between time intervals

Question

In app engine I would like to call a function if the current time is between a particular interval. This is what I am doing now.

ist_time = datetime.utcnow() + timedelta(hours=5, minutes = 30)
ist_midnight = ist_time.replace(hour=0, minute=0, second=0, microsecond=0)
market_open = ist_midnight + timedelta(hours=9, minutes = 55)
market_close = ist_midnight + timedelta(hours=16, minutes = 01)
if ist_time >= market_open and ist_time <= market_close:
    check_for_updates()

Any better way of doing this.

Answer 1

This is more compact, but not so obvious:

if '09:55' <= time.strftime(
   '%H:%M', time.gmtime((time.time() + 60 * (5 * 60 + 30)))) <= '16:01':
  check_for_updates()

Depending on how important it is for you to do the calculations absolutely properly, you may want to consider daylight saving time (use pytz for that -- it is possible to upload pytz bundled to your app to AppEngine) and seconds and millisecods as well (e.g. use < '16:02' instead of <= '16:01', because the former doesn't depend on the second/subsecond precision.

Answer 2

It seems like you might want datetime's "time" type, which doesn't care about date.

import datetime
ist_time = datetime.utcnow() + datetime.timedelta(hours=5, minutes = 30)
# Turn this into a time object (no day information).
ist_time = ist_time.time()
if datetime.time(9, 55) <= ist_time <= datetime.time(16, 1):
   ...

I'm sure there's a more elegant way to handle the timezone adjustment using tzinfo, but I have to confess I've never dealt with timezones.