MooseX::Meta::Attribute::Index - Provides index meta attribute trait
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 $app->get_attribute_name_by_index(1); # returns attr_2 object
This module is a Moose role which implements a meta-attribute, index , using traits. The index meta attribute is useful for ordered of attributes. In standard Moose, attributes are implemented via hash references and order is not preserved. This module implements a meta-attribute that can be used to track the order of attributes where the order of attributes matters. For example, see ODG::Record where maintaining of the order of attributes allows for a Moose class to use an array ref for storage rather than a hash ref.
The indexes must be defined and provided manually. The indexs are checked to ensure that negative indices are not used.
In addition to the meta-attribute, several methods are introduced to work with the indexed attributes. See #methods below. If you just want the meta attribute without the added methods, have your class use the role 'MooseX::Meta::Attribute::Trait::Index'.
The following methods are loaded into your class when this role is used.
Returns the index for the attribute c<$attr_name>
Returns the attribute associated with the index
Returns the attribute name associated with $index
Christopher Brown, "cbrown -at- opendatagroup.com"
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.