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DateTime::TimeZone(3)                User Contributed Perl Documentation               DateTime::TimeZone(3)



NAME
       DateTime::TimeZone - Time zone object base class and factory

VERSION
       version 1.41

SYNOPSIS
         use DateTime;
         use DateTime::TimeZone;

         my $tz = DateTime::TimeZone->new( name => 'America/Chicago' );

         my $dt = DateTime->now();
         my $offset = $tz->offset_for_datetime($dt);

DESCRIPTION
       This class is the base class for all time zone objects.  A time zone is represented internally as a
       set of observances, each of which describes the offset from GMT for a given time period.

       Note that without the "DateTime.pm" module, this module does not do much.  It's primary interface is
       through a "DateTime" object, and most users will not need to directly use "DateTime::TimeZone"
       methods.

USAGE
       This class has the following methods:

   DateTime::TimeZone->new( name => $tz_name )
       Given a valid time zone name, this method returns a new time zone blessed into the appropriate
       subclass.  Subclasses are named for the given time zone, so that the time zone "America/Chicago" is
       the DateTime::TimeZone::America::Chicago class.

       If the name given is a "link" name in the Olson database, the object created may have a different
       name.  For example, there is a link from the old "EST5EDT" name to "America/New_York".

       When loading a time zone from the Olson database, the constructor checks the version of the loaded
       class to make sure it matches the version of the current DateTime::TimeZone installation. If they do
       not match it will issue a warning. This is useful because time zone names may fall out of use, but
       you may have an old module file installed for that time zone.

       There are also several special values that can be given as names.

       If the "name" parameter is "floating", then a "DateTime::TimeZone::Floating" object is returned.  A
       floating time zone does have any offset, and is always the same time.  This is useful for calendaring
       applications, which may need to specify that a given event happens at the same local time, regardless
       of where it occurs.  See RFC 2445 for more details.

       If the "name" parameter is "UTC", then a "DateTime::TimeZone::UTC" object is returned.

       If the "name" is an offset string, it is converted to a number, and a
       "DateTime::TimeZone::OffsetOnly" object is returned.

       The "local" time zone

       If the "name" parameter is "local", then the module attempts to determine the local time zone for the
       system.

       The method for finding the local zone varies by operating system. See the appropriate module for
       details of how we check for the local time zone.

       •   DateTime::TimeZone::Local::Unix

       •   DateTime::TimeZone::Local::Win32

       •   DateTime::TimeZone::Local::VMS

       If a local time zone is not found, then an exception will be thrown.

   $tz->offset_for_datetime( $dt )
       Given a "DateTime" object, this method returns the offset in seconds for the given datetime.  This
       takes into account historical time zone information, as well as Daylight Saving Time.  The offset is
       determined by looking at the object's UTC Rata Die days and seconds.

   $tz->offset_for_local_datetime( $dt )
       Given a "DateTime" object, this method returns the offset in seconds for the given datetime.  Unlike
       the previous method, this method uses the local time's Rata Die days and seconds.  This should only
       be done when the corresponding UTC time is not yet known, because local times can be ambiguous due to
       Daylight Saving Time rules.

   $tz->is_dst_for_datetime( $dt )
       Given a "DateTime" object, this method returns true if the DateTime is currently in Daylight Saving
       Time.

   $tz->name
       Returns the name of the time zone.

   $tz->short_name_for_datetime( $dt )
       Given a "DateTime" object, this method returns the "short name" for the current observance and rule
       this datetime is in.  These are names like "EST", "GMT", etc.

       It is strongly recommended that you do not rely on these names for anything other than display.
       These names are not official, and many of them are simply the invention of the Olson database
       maintainers.  Moreover, these names are not unique.  For example, there is an "EST" at both -0500 and
       +1000/+1100.

   $tz->is_floating
       Returns a boolean indicating whether or not this object represents a floating time zone, as defined
       by RFC 2445.

   $tz->is_utc
       Indicates whether or not this object represents the UTC (GMT) time zone.

   $tz->has_dst_changes
       Indicates whether or not this zone has ever had a change to and from DST, either in the past or
       future.

   $tz->is_olson
       Returns true if the time zone is a named time zone from the Olson database.

   $tz->category
       Returns the part of the time zone name before the first slash.  For example, the "America/Chicago"
       time zone would return "America".

   DateTime::TimeZone->is_valid_name($name)
       Given a string, this method returns a boolean value indicating whether or not the string is a valid
       time zone name.  If you are using "DateTime::TimeZone::Alias", any aliases you've created will be
       valid.

   DateTime::TimeZone->all_names
       This returns a pre-sorted list of all the time zone names.  This list does not include link names.
       In scalar context, it returns an array reference, while in list context it returns an array.

   DateTime::TimeZone->categories
       This returns a list of all time zone categories.  In scalar context, it returns an array reference,
       while in list context it returns an array.

   DateTime::TimeZone->links
       This returns a hash of all time zone links, where the keys are the old, deprecated names, and the
       values are the new names.  In scalar context, it returns a hash reference, while in list context it
       returns a hash.

   DateTime::TimeZone->names_in_category( $category )
       Given a valid category, this method returns a list of the names in that category, without the
       category portion.  So the list for the "America" category would include the strings "Chicago",
       "Kentucky/Monticello", and "New_York". In scalar context, it returns an array reference, while in
       list context it returns an array.

       The list is returned in order of population by zone, which should mean that this order will be the
       best to use for most UIs.

   DateTime::TimeZone->countries()
       Returns a sorted list of all the valid country codes (in lower-case) which can be passed to
       "names_in_country()". In scalar context, it returns an array reference, while in list context it
       returns an array.

       If you need to convert country codes to names or vice versa you can use "Locale::Country" to do so.

   DateTime::TimeZone->names_in_country( $country_code )
       Given a two-letter ISO3166 country code, this method returns a list of time zones used in that
       country. The country code may be of any case. In scalar context, it returns an array reference, while
       in list context it returns an array.

   DateTime::TimeZone->offset_as_seconds( $offset )
       Given an offset as a string, this returns the number of seconds represented by the offset as a
       positive or negative number.  Returns "undef" if $offset is not in the range "-99:59:59" to
       "+99:59:59".

       The offset is expected to match either "/^([\+\-])?(\d\d?):(\d\d)(?::(\d\d))?$/" or
       "/^([\+\-])?(\d\d)(\d\d)(\d\d)?$/".  If it doesn't match either of these, "undef" will be returned.

       This means that if you want to specify hours as a single digit, then each element of the offset must
       be separated by a colon (:).

   DateTime::TimeZone->offset_as_string( $offset )
       Given an offset as a number, this returns the offset as a string.  Returns "undef" if $offset is not
       in the range "-359999" to 359999.

   Storable Hooks
       This module provides freeze and thaw hooks for "Storable" so that the huge data structures for Olson
       time zones are not actually stored in the serialized structure.

       If you subclass "DateTime::TimeZone", you will inherit its hooks, which may not work for your module,
       so please test the interaction of your module with Storable.

SUPPORT
       Support for this module is provided via the datetime@perl.org email list. See
       http://datetime.perl.org/wiki/datetime/page/Mailing_List for details.

       Please submit bugs to the CPAN RT system at
       http://rt.cpan.org/NoAuth/ReportBug.html?Queue=datetime%3A%3Atimezone or via email at
       bug-datetime-timezone@rt.cpan.org.

DONATIONS
       If you'd like to thank me for the work I've done on this module, please consider making a "donation"
       to me via PayPal. I spend a lot of free time creating free software, and would appreciate any support
       you'd care to offer.

       Please note that I am not suggesting that you must do this in order for me to continue working on
       this particular software. I will continue to do so, inasmuch as I have in the past, for as long as it
       interests me.

       Similarly, a donation made in this way will probably not make me work on this software much more,
       unless I get so many donations that I can consider working on free software full time, which seems
       unlikely at best.

       To donate, log into PayPal and send money to autarch@urth.org or use the button on this page:
       http://www.urth.org/~autarch/fs-donation.html <http://www.urth.org/~autarch/fs-donation.html>

CREDITS
       This module was inspired by Jesse Vincent's work on Date::ICal::Timezone, and written with much help
       from the datetime@perl.org list.

SEE ALSO
       datetime@perl.org mailing list

       http://datetime.perl.org/

       The tools directory of the DateTime::TimeZone distribution includes two scripts that may be of
       interest to some people.  They are parse_olson and tests_from_zdump.  Please run them with the --help
       flag to see what they can be used for.

AUTHOR
       Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE
       This software is copyright (c) 2011 by Dave Rolsky.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.



perl v5.12.5                                     2011-10-24                            DateTime::TimeZone(3)