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Moose::Cookbook::Meta::Recipe5.3pm

NAME

Moose::Cookbook::Meta::Recipe5 - The "table" attribute as a metaclass trait

SYNOPSIS

   package MyApp::Meta::Class::Trait::HasTable;
   use Moose::Role;
 
   has table =>
       ( is       => 'rw',
         isa      => 'Str',
       );
 
   package Moose::Meta::Class::Custom::Trait::HasTable;
   sub register_implementation { 'MyApp::Meta::Class::Trait::HasTable' }
 
   package MyApp::User;
   use Moose -traits => 'HasTable';
 
   __PACKAGE__->meta->table('User');
 
 

DESCRIPTION

This recipe takes the metaclass table attribute and reimplements it as a metaclass trait. Traits are just roles that Moose applies to something for you. In this case, that ``something'' is the class's metaclass object.

The advantage of using traits is that it's easy to combine multiple traits, whereas combining multiple metaclasses can be tricky (which subclasses which?).

The disadvantage is that it's not easy to combine a trait with some sort of sugar (like our notional "has_table" sugar).

Using this Metaclass Trait in Practice

Once this trait has been applied to a metaclass, it looks exactly like the example we saw in Moose::Cookbook::Meta::Recipe4:

   my $table = MyApp::User->meta()->table();
 
 

SEE ALSO

Moose::Cookbook::Meta::Recipe3 - Labels implemented via attribute traits

Moose::Cookbook::Meta::Recipe4 - Adding a ``table'' attribute to the metaclass

AUTHOR

Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE

Copyright 2006-2008 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.