recurring system

[Matthew]

Hey guys,
  Does anyone have, already made, some type of recurring events 
module? We have our in-house function that works with singular weekly 
and singular monthly events but we'd like to branch into daily, 
bi-daily, bi-weekly, bi-monthly, every X weeks, every X days, etc.


Our current logic for calculating the next event for a weekly event is 
thus:


  Take the original time stamp of the event. Compare that to current 
time. If eventTimeStamp is greater than current time, return that 
date/time. Otherwise, add 1 week to eventTimeStamp and compare again. 
Loop until eventTimeStamp is greater than current time.


  To me, this seems amazingly inefficient. If my weekly recurring 
original event start date was Aug 1, 2006, the perl would have to loop 
26 times to find the next event (in this case, Jan 23).


Can anyone offer a better solution to this?

Thanks,
Matthew

Re: recurring system

[Matthew]

Well that was easy. Thanks Rick. I should have looked on cpan before 
emailing.


-Matthew

Rick Measham wrote:

Matthew wrote:

Hey guys,
  Does anyone have, already made, some type of recurring events 
module? We have our in-house function that works with singular weekly 
and singular monthly events but we'd like to branch into daily, 
bi-daily, bi-weekly, bi-monthly, every X weeks, every X days, etc.


Like DateTime::Event::Recurrence?

my $bi_daily_at_10_30am_set = DateTime::Event::Recurrence-daily(
   interval = 2,
   hours = 10,
   minutes = 30
);

http://search.cpan.org/dist/DateTime-Event-Recurrence/lib/DateTime/Event/Recurrence.pm 



Cheers!
Rick Measham

Re: recurring system

[Zefram]

Matthew wrote:
  To me, this seems amazingly inefficient. If my weekly recurring 
original event start date was Aug 1, 2006, the perl would have to loop 
26 times to find the next event (in this case, Jan 23).

Can anyone offer a better solution to this?

Yes: determine the day-of-week of the original event, and the week
containing tomorrow, then put them together.  With my Date::ISO8601
module this looks like:

use Date::ISO8601 qw(ymd_to_cjdn cjdn_to_ywd ywd_to_cjdn present_ymd);

my $today_cjdn = ymd_to_cjdn(2007,1,16);
my $initial_cjdn = ymd_to_cjdn(2006,8,1);

(undef, undef, my $repeat_dow) = cjdn_to_ywd($initial_cjdn);
my($next_y, $next_w, $today_dow) = cjdn_to_ywd($today_cjdn + 1);
if($today_dow  $repeat_dow) {
($next_y, $next_w, undef) = cjdn_to_ywd($today_cjdn + 8);
}

print present_ymd(ywd_to_cjdn($next_y, $next_w, $repeat_dow)), \n;

I expect the same algorithm can be implemented using DateTime, but I'm
not a regular user of that, sorry.

-zefram