Moose::Cookbook::Meta::Table_MetaclassTrait - phpMan

NAME
    Moose::Cookbook::Meta::Table_MetaclassTrait - Adding a "table" attribute
    as a metaclass trait

VERSION
    version 2.2200

SYNOPSIS
      # in lib/MyApp/Meta/Class/Trait/HasTable.pm
      package MyApp::Meta::Class::Trait::HasTable;
      use Moose::Role;
      Moose::Util::meta_class_alias('HasTable');

      has table => (
          is  => 'rw',
          isa => 'Str',
      );

      # in lib/MyApp/User.pm
      package MyApp::User;
      use Moose -traits => 'HasTable';

      __PACKAGE__->meta->table('User');

DESCRIPTION
    In this recipe, we'll create a class metaclass trait which has a "table"
    attribute. This trait 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 TRAIT
    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::Debugging_BaseClassRole, which shows how to
    make a module like "Moose.pm" itself, with sugar like "has_table()".

  Using this Metaclass Trait 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 apply the
    "MyApp::Meta::Class::Trait::HasTable" to its metaclass, this method call
    just works. If we want to be more careful, we can check that the class
    metaclass object has a "table" method:

      $table = MyApp::User->meta->table
          if MyApp::User->meta->can('table');

    In theory, this is not entirely correct, since the metaclass might be
    getting its "table" method from a *different* trait. In practice, you
    are unlikely to encounter this sort of problem.

RECIPE CAVEAT
    This recipe doesn't work when you paste it all into a single file. This
    is because the "use Moose -traits => 'HasTable';" line ends up being
    executed before the "table" attribute is defined.

    When the two packages are separate files, this just works.

SEE ALSO
    Moose::Cookbook::Meta::Labeled_AttributeTrait - Labels implemented via
    attribute traits =pod

AUTHORS
    *   Stevan Little <stevan AT cpan.org>

    *   Dave Rolsky <autarch AT urth.org>

    *   Jesse Luehrs <doy AT cpan.org>

    *   Shawn M Moore <sartak AT cpan.org>

    *   יובל קוג'מן (Yuval Kogman) <nothingmuch AT woobling.org>

    *   Karen Etheridge <ether AT cpan.org>

    *   Florian Ragwitz <rafl AT debian.org>

    *   Hans Dieter Pearcey <hdp AT cpan.org>

    *   Chris Prather <chris AT prather.org>

    *   Matt S Trout <mstrout AT cpan.org>

COPYRIGHT AND LICENSE
    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.