NAME

DateTime::TimeZone::Alias - Create aliases for DateTime timezones

SYNOPSIS

    use DateTime::TimeZone::Alias Hawaii => 'Pacific/Honolulu',
                                  EST => 'Australia/Melbourne';

    or

    DateTime::TimeZone::Alias->add( Fun => 'America/Tijuana', %hash );

    or

    DateTime::TimeZone::Alias->set( Pain => 'America/Dawson_Creek', %hash );
    DateTime::TimeZone::Alias->set( boat => 'floating' );
    DateTime::TimeZone::Alias->set( home => 'local' );
    DateTime::TimeZone::Alias->set( lulu => 'Z' );
    DateTime::TimeZone::Alias->set( cut => 'UTC' );
    DateTime::TimeZone::Alias->set( nowhere => '-09:30' );

    or

    DateTime::TimeZone::Alias->remove( qw( Hawaii EST Pain Fun ) );

    or

    DateTime::TimeZone::Alias->value( 'EST' );

    or

    DateTime::TimeZone::Alias->is_defined( 'Hawaii' )
    DateTime::TimeZone::Alias->is_alias( 'EST' )
    DateTime::TimeZone::Alias->is_timezone( 'Antarctica/Vostok' )

    or

    DateTime::TimeZone::Alias->aliases
    DateTime::TimeZone::Alias->timezones

DESCRIPTION

Creates and destroys aliases for DateTime timezones. This module violates the encapsulation of the DateTime internals. User _Beware_.

IMPORT PARAMETERS

Accepts a hash representing an alias and the timezone it should map too. Import has the exact same behaviors as the "set" method.

METHODS

set( alias => timezone, ... )
Accepts a hash representing an alias and the timezone it should map too. If an invalid timezone value or no parameters are passed an exception is thrown. It is possible to create an alias to another alias. This method will redefine an existing alias or add a new alias that overrides an existing timezone.

What may be aliased:
```
    aliases
    floating
    local
    OffsetOnly
    Olson time zones
    UTC
    Z
    
```
add( alias => timezone, ... )
Accepts a hash representing an alias and the timezone it should map too. If an invalid timezone value or no parameters are passed an exception is thrown. It is possible to create an alias to another alias. This method will _not_ redefine an existing alias or allow you remap a timezone. For redefinitions see the "set" method.
remove( alias, ... )
Accepts a list of aliases to be removed. If an the name of an aliases that doesn't exist is passed in then an exception is thrown. It's important to note that you can remove aliases but not timezones. However, a redefined timezone is actually an alias and can be removed.
value( $str )
If $str is a known alias then the timezone being aliased is returned, otherwise undef.
is_defined( $str )
If $str is a known timezone or alias this method returns 1, otherwise undef is returned.
is_alias( $str )
If $str is a known alias this method returns 1, otherwise undef is returned.
is_timezone( $str )
If $str is a known timezone this method returns 1, otherwise undef is returned.
aliases
In list context a hash of all known aliases and their values is returned. In scalar context a reference to a hash is returned.
timezones
In list context an array of all known timezones is returned. In scalar context a reference to an array is returned.

GOTCHAS

Import

Multiple "use DateTime::TimeZone::Alias" statements in the same package may not have the desired result if attempting to redefine existing aliases. If you want to redefine an alias use the "set" method instead.

Aliasing

You can _not_ create circular aliases. E.g.

    # TSH actually points to value of HST - 'Pacific/Honolulu'
    # if HST wasn't already defined this would be an exception
    DateTime::TimeZone::Alias->set( TSH => HST );

    # HST still points to 'Pacific/Honolulu'
    DateTime::TimeZone::Alias->set( HST => TSH );

Sorry - no evil here, move along.

Global Behavior

It's important to remember that aliases are global in scope. E.g.

    package Foo;

    DateTime::TimeZone::Alias->set( EST => 'US/Eastern' );

    Bar->bar();

    # this will fail because EST is no longer defined
    my $dt = DateTime->now( time_zone => 'EST' );

    package Bar;

    sub bar {
        DateTime::TimeZone::Alias->set( EST => 'US/Eastern' );
        .
        .

        DateTime::TimeZone::Alias->remove( qw( EST ) );
    }

There are many possible ways to avoid this trap. The best solution is to simply not write code like this. If you insist on this style then you can try one of the suggested work arounds.

Poor Man's DateTime::TimeZone::Alias

Sometimes DateTime::TimeZone::Alias may not be the best solution to your problem. Particularly if your in an environment that has poor "sand-boxing" such as "mod_perl". E.g.

    use constant EST => 'US/Eastern';

    or

    sub EST () { 'US/Eastern' }
    .
    .

    my $dt = DateTime->new( %params, time_zone => EST );

store/restore

This probably isn't thread safe. E.g.

    sub bar {
        my $my_alias = DateTime::TimeZone::Alias->value( 'EST' );
        DateTime::TimeZone::Alias->set( EST => 'US/Eastern' );
        .
        .

        DateTime::TimeZone::Alias->set( EST => $my_alias );
    }

If $my_alias is undefined then the "set" will fail as an alias must point to a valid timezone.

DEVELOPER NOTES

The "aliases" and "timezones" methods preserve encapsulation by returning a reference to a copy of the internal data structures instead of a direct reference.

CREDITS

Ben Bennett (BBENNETT) for a bug report, some API suggestions, documentation suggestions, and being so darn enthusiastic. (not necessary in that order)

Everyone at the DateTime "Asylum".

SUPPORT

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

AUTHOR

Joshua Hoblitt <jhoblitt@cpan.org>

COPYRIGHT

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