DateTime::TimeZone man page on Scientific

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

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

	 use DateTime;
	 use DateTime::TimeZone;

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

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

       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 "" 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.

       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

       ·   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.

       Returns the name of the time zone.  If this value is passed to the
       "new()" method, it is guaranteed to create the same object.

   $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.

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

       Indicates whether or not this object represents the UTC (GMT) time

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

       Returns true if the time zone is a named time zone from the Olson

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

       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.

       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.

       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.

       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.

       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 for this module is provided via the email
       list. See for details.

       Please submit bugs to the CPAN RT system at
       or via email at

       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

       To donate, log into PayPal and send money to or use
       the button on this page:

       Dave Rolsky <>

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

       Copyright (c) 2003-2008 David Rolsky.  All rights reserved.  This
       program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

       The full text of the license can be found in the LICENSE file included
       with this module.

SEE ALSO mailing list

       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.

perl v5.10.1			  2013-11-21		 DateTime::TimeZone(3)

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