NAME
Moose::Cookbook::Extending::Recipe1 - Providing an alternate base object class
SYNOPSIS
package MyApp::Base;
use Moose;
extends 'Moose::Object';
before 'new' => sub { warn "Making a new " . $_[0] };
no Moose;
package MyApp::UseMyBase;
use Moose ();
use Moose::Exporter;
Moose::Exporter->setup_import_methods( also => 'Moose' );
sub init_meta {
shift;
Moose->init_meta( @_, base_class => 'MyApp::Object' );
}DESCRIPTION
Often you find that you want to share some behavior between all your classes. One way to do that is to make a base class and simply add extends 'MyApp::Base' to every class in your application. However, that can get tedious. Instead, you can simply create your Moose-alike module that sets the base object class to MyApp::Base for you.
Then, instead of writing use Moose you can write use MyApp::UseMyBase.
In this particular example, our base class issues some debugging output every time a new object is created, but you can surely think of some more interesting things to do with your own base class.
This all works because of the magic of Moose::Exporter. When we call Moose::Exporter->setup_import_methods( also => 'Moose' ) it builds an import and unimport method for you. The also => 'Moose' bit says that we want to export everything that Moose does.
The import method that gets created will call our init_meta method, passing it for_caller => $caller as its arguments. The $caller is set to the class that actually imported us in the first place.
See the Moose::Exporter docs for more details on its API.
USING MyApp::UseMyBase
To actually use our new base class, we simply use MyApp::UseMyBase instead of Moose. We get all the Moose sugar plus our new base class.
package Foo;
use MyApp::UseMyBase;
has 'size' => ( is => 'rw' );
no MyApp::UseMyBase;AUTHOR
Dave Rolsky <autarch@urth.org>
COPYRIGHT AND LICENSE
Copyright 2006-2008 by Infinity Interactive, Inc.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.