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Moose::Cookbook::Meta::Recipe4.3pm
Langue: en
Version: 2009-04-20 (debian - 07/07/09)
Section: 3 (Bibliothèques de fonctions)
Sommaire
NAME
Moose::Cookbook::Meta::Recipe4 - Adding a "table" attribute to the metaclassSYNOPSIS
package MyApp::Meta::Class; use Moose; extends 'Moose::Meta::Class'; has table => ( is => 'rw', isa => 'Str', );
DESCRIPTION
In this recipe, we'll create a new metaclass which has a ``table'' attribute. This metaclass is for classes associated with a DBMS table, as one might do for an ORM.In this example, the table name is just a string, but in a real ORM the table might be an object describing the table.
THE METACLASS
This really is as simple as the recipe ``SYNOPSIS'' shows. The trick is getting your classes to use this metaclass, and providing some sort of sugar for declaring the table. This is covered in Moose::Cookbook::Extending::Recipe2, which shows how to make a module like "Moose.pm" itself, with sugar like "has_table()".Using this Metaclass in Practice
Accessing 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 use "MyApp::Meta::Class" as its metaclass, this method call just works. If we want to be more careful, we can check the metaclass's class:
$table = MyApp::User->meta->table if MyApp::User->meta->isa('MyApp::Meta::Class');
CONCLUSION
Creating custom metaclass is trivial. Using it is a little harder, and is covered in other recipes. We will also talk about applying traits to a class metaclass, which is a more flexible and cooperative implementation.SEE ALSO
Moose::Cookbook::Meta::Recipe5 - The ``table'' attribute implemented as a metaclass traitMoose::Cookbook::Extending::Recipe2 - Acting like Moose.pm and providing sugar Moose-style
AUTHOR
Dave Rolsky <autarch@urth.org>COPYRIGHT AND LICENSE
Copyright 2006-2009 by Infinity Interactive, Inc.<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre