Phileas Fogg avait, «sans s'en douter», gagné un jour sur son itinéraire, - et cela uniquement parce qu'il avait fait le tour du monde en allant vers l'est, et il eût, au contraire, perdu un jour en allant en sens inverse, soit vers l'ouest.
— Le Tour du monde en quatre-vingts jours (Jules Vernes)
An module to extend the built in
DateTime with timezone support.
To use, simply include it at any point in your code:
my $dt = DateTime.new: now;
DateTime to include the following three new attributes whose names are subject to change.
The unique identifier for the timezone.
These are maintained by the IANA and based around city names, in the format of Region/City, and occasionally Region/Subregion/City.
They do not tend to align with popular usage. In the United States, for instance, what is commonly called Eastern Time is listed as America/New_York).
An (mostly) unique abbreviation for the timezone.
It normally is more representative of popular usage (so EST for Eastern Standard Time in America/New_York) and normally differs based on daylight savings time.
This value is
True if the timezone is in what is commonly referred to as either Daylight Saving Time (hence the attribute name) or Summer Time where the timezone is shifted by (normally) one hour.
The value is
False during Standard time which in many timezones is the only possible value.
For the most part, once you enable it, you won't need to do anything different at all, as it is designed to be as discreet as possible.
There are, nonetheless, a few things to note:
- The default time zone is either Etc/GMT or (NYI) if you have
Intl::UserTimezone, the one indicated by
- The attribute
timezone has been modified slightly to be allomorphic.
For creation, you may pass either an
Int offset or a
Str Olson ID.
Integer offsets are taken into account but the resultant time will be zoned to GMT (eventually whole-hour offsets will be be given an appropriate
.timezone, you get an
IntStr comprising the offset and the Olson ID, so it should Just Work™.
If you absolutely must have a strict
Int value, use
.offset, and for a strict
Str value, use
.Str method will lose the timezone information.
.earlier() methods are currently untested.
You may get unexpected results if you use them and cross a timezone transition.
- You should only use this on your executed script.
Modules that wish to take advantage of
DateTime::Timezones should not
useit, and instead assume that the methods exist.
If functionality is critical, you can try sticking in a
die unless DateTime.^can('is-dst') that will be executed at runtime.
This is due to a bug in Rakudo where the original methods of wrapped methods are deleted. I am working to create a workaround.
- Creation via a string is untested and will likely result in errors for the time being (this will be fixed)
Leapseconds are annoying for timekeeping and POSIX explicitly ignores them since future ones are unpredictable because weird physics.
I have yet to rigorously test that leapseconds are handled correctly, but welcome any code review and/or pull requests to remedy this (particularly test cases).
How does it work?
While the module initially planned on
DateTime, it turns out that has significant problems for things like precompilation (you can't) and requires enabling
MONKEY-TYPING which just feels dirty.
DateTime.new was wrapped with a new method that returned the same (or functionally the same)
DateTime you would have expected and mixes in the parameterized
It had a few tricks to make sure it doesn't apply the role multiple times. Now, it uses a new technique pioneered by Elizabeth Mattijsen to avoid some of the wraps, and uses the earlier techniques for protecting any precompiled core
The data files come from the IANA, and are compiled using their zone information compiler (ZIC) prior to distribution.
- Timezone data reading moved to a new
- Links (in new module) are handled in code, reducing file size
- Calculation errors fixed, especially for future dates, thanks to...
- ...new handling of v.3 data files
- Test files regarding accuracy moved to that module
- Should "just work" when module is used inside of another module (though additional testing is still required here)
- Requires Rakudo 2021.10 or later
- Fixed an issue caused by changes to the ZIC compiler
-b fat option is used for backwards compatibility
- Upcoming 0.4 release will better understand TZif v2+ files and fix some calculation errors
- Updated to the 2021e release
- Minor (but urgent) update for Palestine
- Updated to the 2021d release
- Fiji updated (no DST for 2021–2022)
- Updated to the 2021c release
- Fixed typos for the Atlantic/Jan_Mayen link (and America/Virgin, we ignore backzones).
- Updated to the 2021b release
- Jordan and Samoa updated
- Zone mergers and renamings
- Pre-1993 fixes for Malawi, Portugal, etc - 0.3.5
- Updated to the 2021a release
- South Sudan, Russia (Volgograd), Turks and Caicos updated
- Many other zones fixed for pre-1986 transitions
- Added support for historical Olson IDs (mainly to provide better support with CLDR)
- Updated updater script to automatically back link older IDs.
- Upgraded database to the 2020d release
- Minor (but urgent) update for Palestine
- Upgraded database to the 2020c release
- Fixed bugs (found by ZeroDogg) caused when creating DateTimes with values other than
- Upgraded database to the 2020b release
- Minor updates for Antarctica, Australia, Canada, and Morocco.
- Fixed an install issue due to evil
.DS_Store files (thanks to ZeroDogg for bringing it to my attention).
- Minor adjustments to the updater script
- Support for 'upgrading' timezone-unaware
DateTime objects that may have been precompiled before this module's
- Additional test files.
- Added an example: see
world-clock.raku and pass in your favorite timezones
- Fixed creation from Instants by adding
- TZif files generated on our own directly from the TZ database.
- Fixed error in parsing leapseconds from TZif files
- Fixed offset calculation error caused by misreading C code
- Added test files (but more are needed, esp for leapseconds)
- Created automated updater script for ease of maintenance.
- First release.
- Basic support for creation of
DateTime with timezone information.