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NAMEMoose::Cookbook::Meta::Table_MetaclassTrait - Adding a "table" attribute as a metaclass trait
# in lib/MyApp/Meta/Class/Trait/HasTable.pm package MyApp::Meta::Class::Trait::HasTable; use Moose::Role; Moose::Util::meta_class_alias('HasTable'); has table => ( is => 'rw', isa => 'Str', ); # in lib/MyApp/User.pm package MyApp::User; use Moose -traits => 'HasTable'; __PACKAGE__->meta->table('User');
DESCRIPTIONIn this recipe, we'll create a class metaclass trait which has a ``table'' attribute. This trait is for classes associated with a
In this example, the table name is just a string, but in a real
THE METACLASS TRAITThis really is as simple as the recipe ``
Using this Metaclass Trait in PracticeAccessing this new "table" attribute is quite simple. Given a class named "MyApp::User", we could simply write the following:
my $table = MyApp::User->meta->table;
As long as "MyApp::User" has arranged to apply the "MyApp::Meta::Class::Trait::HasTable" to its metaclass, this method call just works. If we want to be more careful, we can check that the class metaclass object has a "table" method:
$table = MyApp::User->meta->table if MyApp::User->meta->can('table');
In theory, this is not entirely correct, since the metaclass might be getting its "table" method from a different trait. In practice, you are unlikely to encounter this sort of problem.
RECIPE CAVEATThis recipe doesn't work when you paste it all into a single file. This is because the "use Moose -traits => 'HasTable';" line ends up being executed before the "table" attribute is defined.
When the two packages are separate files, this just works.
SEE ALSOMoose::Cookbook::Meta::Labeled_AttributeTrait - Labels implemented via attribute traits =pod
- Stevan Little <firstname.lastname@example.org>
- Dave Rolsky <email@example.com>
- Jesse Luehrs <firstname.lastname@example.org>
- Shawn M Moore <email@example.com>
- יובל קוג'מן (Yuval Kogman) <firstname.lastname@example.org>
- Karen Etheridge <email@example.com>
- Florian Ragwitz <firstname.lastname@example.org>
- Hans Dieter Pearcey <email@example.com>
- Chris Prather <firstname.lastname@example.org>
- Matt S Trout <email@example.com>
COPYRIGHT AND LICENSEThis software is copyright (c) 2006 by Infinity Interactive, Inc.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.