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https://github.com/schwern/datetime-timezone

Release history of DateTime-TimeZone
https://github.com/schwern/datetime-timezone

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Release history of DateTime-TimeZone

Host: GitHub
URL: https://github.com/schwern/datetime-timezone
Owner: schwern
License: other
Created: 2009-12-18T01:03:58.000Z (about 15 years ago)
Default Branch: master
Last Pushed: 2009-12-11T20:21:22.000Z (about 15 years ago)
Last Synced: 2024-10-29T20:09:07.222Z (3 months ago)
Language: Perl
Homepage: http://search.cpan.org/dist/DateTime-TimeZone/
Size: 5.05 MB
Stars: 1
Watchers: 2
Forks: 1
Open Issues: 0
Metadata Files:
- Readme: README
- Changelog: Changes
- License: LICENSE

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README

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

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->name
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.

$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 [email protected] email
list. See http://datetime.perl.org/?MailingList 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 [email protected].

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 [email protected] or use the
button on this page: http://www.urth.org/~autarch/fs-donation.html

AUTHOR
Dave Rolsky

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

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