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Moose::Cookbook::Extending::Recipe3(3)			User Contributed Perl Documentation		    Moose::Cookbook::Extending::Recipe3(3)

NAME
Moose::Cookbook::Extending::Recipe3 - Providing an alternate base object class VERSION
version 2.0205 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; return Moose->init_meta( @_, base_class => 'MyApp::Base' ); } DESCRIPTION
A common extension is to provide an alternate base class. One way to do that is to make a "MyApp::base" and add "extends 'MyApp::Base'" to every class in your application. That's pretty tedious. Instead, you can create a 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 think of some more interesting things to do with your own base class. This uses the magic of Moose::Exporter. When we call "Moose::Exporter->setup_import_methods( also => 'Moose' )" it builds "import" and "unimport" methods 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; CONCLUSION
This is an awful lot of magic for a simple base class. You will often want to combine a metaclass trait with a base class extension, and that's when this technique is useful. AUTHOR
Stevan Little <stevan@iinteractive.com> COPYRIGHT AND LICENSE
This software is copyright (c) 2011 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. perl v5.12.5 2011-09-06 Moose::Cookbook::Extending::Recipe3(3)

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Moose::Cookbook::Meta::Recipe4(3)			User Contributed Perl Documentation			 Moose::Cookbook::Meta::Recipe4(3)

NAME
Moose::Cookbook::Meta::Recipe4 - Adding a "table" attribute to the metaclass VERSION
version 2.0205 SYNOPSIS
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 trait Moose::Cookbook::Extending::Recipe2 - Acting like Moose.pm and providing sugar Moose-style AUTHOR
Stevan Little <stevan@iinteractive.com> COPYRIGHT AND LICENSE
This software is copyright (c) 2011 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. perl v5.12.5 2011-09-06 Moose::Cookbook::Meta::Recipe4(3)
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