Страницы справочника OS X

Эта страница руководства для  версии 10.9 Mac OS X

Читать страницы руководства

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)