++ed by:
AYOUNG ADAMJS ARPI JRMASH DROLSKY
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Author image Dave Rolsky

NAME

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

SYNOPSIS

  use DateTime::TimeZone

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

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.

USAGE

This class has the following methods:

  • 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".

    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 "local", then the local time zone of the current system is used. This is determined by first looking at $ENV{TZ}. If this contains a number or an offset string, it is treated as the offset. Otherwise, the local offset is calculated by comparing the difference between the Time::Local module's timegm() and timelocal() functions. Either way, the offset is used to create a DateTime::TimeZone::OffsetOnly object.

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

    Finally, if the "name" is a number or an offset string, that is converted to a number and a DateTime::TimeZone::OffsetOnly object is returned.

  • offset_for_datetime( $datetime )

    Given an object which implements the DateTime.pm API, 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.

  • offset_for_local_datetime( $datetime )

    Given an object which implements the DateTime.pm API, 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.

  • name

    Returns the name of the time zone, as given in the Olson database.

  • short_name_for_datetime( $datetime )

    Given an object which implements the DateTime.pm API, 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.

  • is_floating

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

  • is_utc

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

  • category

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

This class also contains several functions, none of which are exported.

  • 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.

  • 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.

  • 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.

  • offset_as_seconds( $offset )

    Given an offset as a string or number, this returns the number of seconds represented by the offset as a positive or negative number.

  • offset_as_string( $offset )

    Given an offset as a string or number, this returns the offset as string.

SUPPORT

Support for this module is provided via the datetime@perl.org email list. See http://lists.perl.org/ for more details.

AUTHOR

Dave Rolsky <autarch@urth.org>, inspired by Jesse Vincent's work on Date::ICal::Timezone, and with help from the datetime@perl.org list.

COPYRIGHT

Copyright (c) 2003 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

datetime@perl.org mailing list

http://datetime.perl.org/