Re: Addition of calendar to intl

On Wed, 18 Apr 2012 23:54:00 +0200, Stas Malyshev <smalyshev@sugarcrm.com> wrote:

I think the documentation part in this case is not as problematic, because the interface has been thoroughly documented in the ICU project. Most of your next questions can be answered by reading http://userguide.icu-project.org/datetime/calendar

This is ICU docs, not PHP docs. Most PHP users wouldn't even know where to find it, let alone how to use it applied to PHP. We need something to list the functions and what they do.

It's ICU docs, but they're applicable here after doing the obvious substitutions (replace all integer types with PHP's integer, etc.). You can list the functions with php --rc IntlCalendar or similar and then refer to that document for the functions' behavior. Of course, this doesn't replace PHP documentation, but it's not urgent at this stage given PHP 5.5 being one year away and the ICU docs giving almost all information to those who want to play with it.

See http://userguide.icu-project.org/datetime/calendar#TOC-Usage

OK, I see but it refers to UDate and operations with it - does it duplicate what we do with DateTime? What would be typical use case - to use DateTime or your calendar functions? Would I have to keep dates in two separate forms? How this interacts with DateTime?

"UDate is a scalar value that indicates a specific point in time, independent of calendar system and local time zone. It is stored as the number of milliseconds from a reference point known as the epoch. The epoch is midnight Universal Time Coordinated (UTC) January 1, 1970 A.D. Negative UDate values indicate times before the epoch." (http://userguide.icu-project.org/datetime#TOC-How-ICU-Represents-Dates-Times ) UDate is just a typedef for double, and is represented in PHP with the float type. As for DateTime, IntlGregorianCalendar (a specific type of IntlCalendar) *DOES* duplicate some functionality of DateTime. There are some things DateTime does that IntlGregorianCalendar doesn't (like formatting and parsing, which is done in intl through IntlDateFormatter) and there are things that IntlGregorianCalendar does that DateTime doesn't (refer to my previous e-mails on this thread). I'm working on some interoperability with the two; see https://github.com/cataphract/php-src/commit/e6c4dc8

The main drive for creating a IntlTimeZone class was simply to encapsulate ICU TimeZone objects, which the Calendar classes work with. Therefore, the support is limited and only the base ICU class for timezones is exposed, except for the methods that allow changing the TimeZone. ICU allows you to build timezones with arbitrary rules, import/export RFC2445 VTIMEZONE and a lot more, none of which are available with my patch.

I'd say if we already have this class why not support at least most useful things? I'd find VTIMEZONE support definitely very useful.

Patches welcome :) More seriously, adding complete support for time zones is time consuming because it implies also supporting the classes with which the subclasses of TimeZone collaborate -- for instance, the several types of DST rules. Maybe it's possible to work around that without compromising having full support in the future -- I'm happy to hear ideas.

Still, there is already some functionality that doesn't exist in DateTimeZone, like timezone id canonization, localization of time zone names on 8 different formats and easier searching for timezones according to country and region.

Is there an easy way to get from DateTimeZone to intl one and back (at least for standard ones, custom ones probably won't work)?

Again, I'm working on that: https://github.com/cataphract/php-src/commit/361cf32 I'll post something to this list for review when I have something ready. -- Gustavo Lopes