 |
lua-l archive |
|
|
||
|
|
i am not comparing to datetimes as a whole. i dont have to know if now() is between "may/5 from 1pm" and "june/20 up to 5pm" date-range and time-range are independent each other. i am working on a scheduler: while(true) -- sleep a while... campaign = tell_me_if_a_campaign_must_be_executed(table_campaigns) end table_campaigns have this definitions record 1 this_campaign_applies_from_date = may/6/2008 this_campaign_applies_up_to_date = jun/20/2009 this_campaign_applies_on_this_time = 1pm this_campaign_applies_up_to_this_time = 2pm record [n] ... function tell_me_if_a_campaign_must_be_executed() must loop into the table, read it records and analize field decribed above. so, first it compares if today is between the date-ranges of the record, if so, then it must compare if this clock-time is between the time-range of the record user input is not a problem here, since i write manually the records-vector my problem is how to compare the os.clock and the fields. thanks again, > Date: Fri, 8 May 2009 00:26:00 +0800 > From: keinhong@gmail.com > To: lua@bazar2.conectiva.com.br > Subject: Re: how to compare 2 dates - NOW WITH TIME > > Diego - Red Baires wrote: >> [snip] >> premise: >> i need to represent a range or dates, and then a range of time. >> i have a list of records that indicates that an event must be >> executed only if: >> a) today is between the fields that indicates a range of dates, and then >> b) os system.clock is between the fields that indicates a range of hours. >> >> (is today between date-A and date-B, if so, is now between 3pm and 4pm?) >> >> so i am doing this: >> >> ----------- >> between_date_from = os.time({ year="2008", month="01", day="01", >> hour="00", min="00" }) >> between_date_to = os.time({ year="2009", month="05", day="06", >> hour="00", min="00" }) > > On many platforms, this os.time() function which calls the > platform's equivalent will happily accept 'illegal' values like > month=13 or day=40. You'd get sorta a 'best guess' value. (Note: > You supply numbers; strings like "2009" are turned into numbers > like 2009. You might also not need to supply zero fields like > min=0, because the function does a best guess.) > > Thus validating a date is non-trivial. Also, depending on user > input, dates are of various precisions. More validation, if your > application expects certain formats or precisions. Then to be > precisely precise, you'd also need to accept sec=60 for some > years, which of course, I think most OS don't deal with a leap > second in the OS layer. Then there is nntp synchronization. And so on. > >> [snip snip] >> now the problem is how to analize a range of hours, not taking in mind >> the date. >> any idea ? >> >> "os.time()" does not allow (obviously) an assignation like this: >> { year="0000", month="00", day="00", hour="17", min="30" } > > os.time() on most platforms (POSIX-ish) is the number of seconds > after the Unix epoch. You can trivially compare and subtract the > times. The difference is in seconds, which you can then convert > into anything you like. > > If you are in total control of an application, and need a standard > textual format for date/time, then use ISO 8601 [1](or a subset), > and make your users use it. Make your program validate ISO 8601 > time formats. Once it validates correctly, common ISO 8601 formats > like YYYY-MM-DD can also be compared trivially in string form. > Using the ISO form also avoids ambiguity common with date/time > formats of different countries. More info in [1], link below. > > [1] http://en.wikipedia.org/wiki/ISO_8601 > > -- > Cheers, > Kein-Hong Man (esq.) > Kuala Lumpur, Malaysia Invite your mail contacts to join your friends list with Windows Live Spaces. It's easy! Try it! |