Fixing datime and working with it

[hayri]

Hi everyone, I have two questions about datime method (may I call it a
method at all?).

1) The datime is giving me the wrong time. It's 15:40 right now bu
it's showing 13:40. How and where to fix it?

2) How can I make comparisons between dates and other operations with
the current time. Let's say I want to fire an afternoon_event if the
current time is between 12:00 (a.m.) and 20:00. How to do that? I
could only find the following example:
alarmAbsoluteDatime(ct(X),D2) <- at(X) 'where' (
current_datime(D1), datime_plus_sec(D1,3,D2) ).

But it would be nice to know if it's possible to compare dates or give
a precise time for an event.

hayri

[Paul Fodor]

Hi Hayri,
Yes, you can compare date-times, add periods of time, etc.
We tried to support multiple Prolog interpreters, so, these methods
are implemented differently for various Prologs. Even running on
Windows or Linux makes a difference (the same datime/1 method in Yap
doesn't work in Windows).
Please look in the src/date_time.P
or online:
http://code.google.com/p/etalis/source/browse/etalis/src/date_time.P

1) Please check your time zone on the computer that you are running
your tests on. The methods are straight forward, so I can only assume
that it takes the Greenwich Time.

2) Please try something like this:
current_datime(datime(Y,M,D,H,Min,Sec)),
less_datime(datime(Y,M,D,H,Min,Sec,0),
datime(T2_Y,T2_M,T2_D,T2_H,T2_Min,T2_S,T2_Counter))

The reason why we added that counter at datime was that a sequence of
events are encountered during a second and the order they came in is
important for CEP.

Regards,
Paul.

[Paul Fodor]

Hi Hayri,
I modified that predicate, so you don't need to add the counter if you
just want to compare datime structures.
Please update the source code from the SVN repository.
Regards,
Paul.

[hayri]

Thanks Paul, it really worked with less_datime

I also checked my time zone. It's GMT+1, but Etalis shows 2 hours
difference. I don't get it but it's no big deal now.

I took a look at date_time.P file. There are really some helpful
methods but I would like to implement my own methods too. For instance
I could invert the "less_datime" method and name it "more_datime" or
something like that. I could then define another "between_datime"
method and so on.
The question is, is it allowed to do that. If yes, is it enough to
implement the method in that file or do I need to declare it somewhere
else too?

[PF]

Yes, great. Please modify that file. We can add you as a developer to
the project.
Regards,
Paul.