NAME
MooseX::Meta::Attribute::Index - Provides index meta attribute trait
SYNOPSIS
package App;
use Moose;
with 'MooseX::Meta::Attribute::Index';
has attr_1 => (
traits => [ qw/Index/ ] ,
is => 'rw' ,
isa => 'Str' ,
index => 0
);
has attr_2 => (
traits => [ qw/Index/ ] ,
is => 'rw' ,
isa => 'Int' ,
index => 1
) ;
package main;
my $app = App->new( attr_1 => 'foo', attr_2 => 42 );
$app->get_attribute_index( "attr_1" ); # 0
$app->get_attribute_index( "attr_2" ); # 1
$app->get_attribute_by_index(0); # returns attr_1 object
$app->get_attribute_by_index(1); # returns attr_2 object
$app->get_attribute_name_by_index(0); # returns attr_1 object
$app->get_attribute_name_by_index(1); # returns attr_2 objectDESCRIPTION
This module is a Moose role which implements a meta-attribute, index , using traits. The index meta attribute is useful for ordered of attributes. In standard Moose, attributes are implemented via hash references and order is not preserved. This module implements a meta-attribute that can be used to track the order of attributes where the order of attributes matters. For example, see ODG::Record where maintaining of the order of attributes allows for a Moose class to use an array ref for storage rather than a hash ref.
The indexes must be defined and provided manually. The indexs are checked to ensure that negative indices are not used.
In addition to the meta-attribute, several methods are introduced to work with the indexed attributes. See #methods below.
METHODS
The following methods are loaded into your class when this role is used.
- get_attribute_index( $attr_name )
-
Returns the index for the attribute c<$attr_name>
- get_attribute_by_index( $index )
-
Returns the attribute associated with the index
- get_attribute_name_by_index( $index )
-
Returns the attribute name associated with $index
SEE ALSO
AUTHOR
Christopher Brown, "cbrown -at- opendatagroup.com"
COPYRIGHT AND LICENSE
Copyright (C) 2008 by Open Data
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.10.0 or, at your option, any later version of Perl 5 you may have available.