Time/Date based suppression system

Question

We're coding a system that parses time based events, and we'd like to implement a suppression system for these events where we can give cron-like syntax for matching against.

e.g. suppress if...

1. .. the event occurs on the last Friday of the month
2. .. the event occurs between 4pm and 5pm weekdays
3. .. the event occurs on a Sunday

and so on.

We're using Python so I was hoping there may be a module for doing this type of thing, but my search skills are letting me down (lots of results about scheduling events, whereas I want the opposite - does the current time match a defined schedule).

Alternatively I'm happy writing one from scratch if anyone has any suggestions for the best way of storing and comparing a time against a schedule.

Edit:

To clarify, the suppression schedules are not set in stone so I cannot simply code a function to handle specific cases. The schedules need to be stored in a database, and tied to an event, so I can do roughly:

sql_rows = ..... "SELECT * FROM suppressions WHERE event_id = ?"

for row in sql_rows:
    if matchesSchedule(current_time,row):
        print "This should be suppressed"

So I need to represent the schedule in a format that I can store in a table, and then match columns against the current time components.

Answer 1

I propose to simply implement your time pattern checkers yourself. That's pretty straight-forward using sth like the datetime object (you could use time as well if you like that better). And in Python syntax you can even express things like "the sum of the number of minutes, hours, and seconds shall be 42", i. e. things which are not possible using cron-like patterns.

import datetime

def matchesTimePattern1(d):
  return (
    d.weekday() == 4 and  # Friday?
    d.month != (d + datetime.timedelta(7)).month  # next week is different month?
  )

def matchesTimePattern2(d):
  return (
    d.weekday() in (0, 1, 2, 3, 4) and  # weekday?
    d.hour == 16  # at 4pm (up to 4:59:59pm)
  )

def matchesTimePattern3(d):
  return (
    d.weekday() == 6  # Sunday?
  )

d = datetime.datetime.now()
print matchesTimePattern1(d)
print matchesTimePattern2(d)
print matchesTimePattern3(d)