Moose::Cookbook::Legacy::Table_ClassMetaclass - Adding a "table" attribute to the metaclass |
Moose::Cookbook::Legacy::Table_ClassMetaclass - Adding a ``table'' attribute to the metaclass
version 2.1605
package MyApp::Meta::Class; use Moose; extends 'Moose::Meta::Class';
has table => ( is => 'rw', isa => 'Str', );
WARNING: Subclassing metaclasses (as opposed to providing metaclass traits) is strongly discouraged. This recipe is provided solely for reference when encountering older code that does this.
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.
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
the Moose::Cookbook::Extending::Recipe2 manpage, which shows how to make a
module like Moose.pm
itself, with sugar like has_table()
.
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');
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.
the Moose::Cookbook::Meta::Recipe5 manpage - The ``table'' attribute implemented as a metaclass trait
the Moose::Cookbook::Extending::Recipe2 manpage - Acting like Moose.pm and providing sugar Moose-style
This 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.
Moose::Cookbook::Legacy::Table_ClassMetaclass - Adding a "table" attribute to the metaclass |