NAME

DateTime::US - Provides time zone and Daylight Saving Time (DST) information for US states and territories

SYNOPSIS

use DateTime::US;

DESCRIPTION

Module DateTime::US provides a class and functions used to help Raku programs needing US time zone and DST information. The user creates a DateTime::US object by providing a US time zone abbreviation. The list of known data may be listed without an object:

$ raku
> use DateTime::US;
> show-us-data;

The main use case that motivated the module is to convert time in UTC to local time for creating calendars and almanacs. For example, local Sunrise is given in UTC and will normally be shown on a calendar in local time:

my $tz = DateTime.new: :timezone('CST');
my $sunrisez = 2022-10-03T05:45:00Z;
my $localtime = $tz.to-local :utc($sunrisez);

Class methods

• to-localtime(DateTime :$utc! --> DateTime) {...}

  Given a time in UTC, convert to local time and adjust for DST.

• to-utc(DateTime :$localtime! --> DateTime) {...}

  Given a local time, convert to UTC with adjustment for DST.

Subroutines

• begin-dst($year --> DateTime) {...}

  Return the time when DST begins.

• end-dst($year --> DateTime) {..}

  Return the time when DST ends.

• is-dst(DateTime :$localtime! --> Bool) {...}

  Return True if the local time is DST, otherwise return False.

• show-us-data(--> Str) {...}

  List the time zone and DST data being used.

SEE ALSO

• Module DateTime::Timezones

  In contrast to Matthew Stuckwisch's module, this module does not use any of the IANA timezone database and relies only on the power of the Raku DateTime type, the short list of time zone UTC offsets for standard US time zones, and the standard dates and time of Daylight Saving Time begin/end enshrined in US Public Law.

Todo

Provide handling for the exceptions to use of DST where indicated.

Note

The author is happy to create or collaborate on a similar module for other regions. If interested, simply file an issue or discuss it on IRC #raku (author's handle is 'tbrowder').

AUTHOR

Tom Browder [email protected]

COPYRIGHT AND LICENSE

Copyright © 2021 Tom Browder

This library is free software; you may redistribute or modify it under the Artistic License 2.0.