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1 | |
2 | =pod |
3 | |
4 | =head1 NAME |
5 | |
6 | Moose::Cookbook::Meta::Recipe4 - Adding a "table" attribute to the metaclass |
7 | |
8 | =head1 SYNOPSIS |
9 | |
10 | package MyApp::Meta::Class; |
11 | use Moose; |
12 | extends 'Moose::Meta::Class'; |
13 | |
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14 | has table => ( |
15 | is => 'rw', |
16 | isa => 'Str', |
17 | ); |
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18 | |
19 | =head1 DESCRIPTION |
20 | |
21 | In this recipe, we'll create a new metaclass which has a "table" |
22 | attribute. This metaclass is for classes associated with a DBMS table, |
23 | as one might do for an ORM. |
24 | |
25 | In this example, the table name is just a string, but in a real ORM |
26 | the table might be an object describing the table. |
27 | |
28 | =head1 THE METACLASS |
29 | |
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30 | This really is as simple as the recipe L</SYNOPSIS> shows. The trick |
31 | is getting your classes to use this metaclass, and providing some sort |
32 | of sugar for declaring the table. This is covered in |
33 | L<Moose::Cookbook::Extending::Recipe2>, which shows how to make a |
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34 | module like C<Moose.pm> itself, with sugar like C<has_table()>. |
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35 | |
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36 | =head2 Using this Metaclass in Practice |
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37 | |
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38 | Accessing this new C<table> attribute is quite simple. Given a class |
39 | named C<MyApp::User>, we could simply write the following: |
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40 | |
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41 | my $table = MyApp::User->meta->table; |
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42 | |
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43 | As long as C<MyApp::User> has arranged to use C<MyApp::Meta::Class> as |
44 | its metaclass, this method call just works. If we want to be more |
45 | careful, we can check the metaclass's class: |
46 | |
47 | $table = MyApp::User->meta->table |
48 | if MyApp::User->meta->isa('MyApp::Meta::Class'); |
49 | |
50 | =head1 CONCLUSION |
51 | |
52 | Creating custom metaclass is trivial. Using it is a little harder, and |
53 | is covered in other recipes. We will also talk about applying traits |
54 | to a class metaclass, which is a more flexible and cooperative |
55 | implementation. |
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56 | |
57 | =head1 SEE ALSO |
58 | |
59 | L<Moose::Cookbook::Meta::Recipe5> - The "table" attribute implemented |
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60 | as a metaclass trait |
61 | |
62 | L<Moose::Cookbook::Extending::Recipe2> - Acting like Moose.pm and |
63 | providing sugar Moose-style |
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64 | |
65 | =head1 AUTHOR |
66 | |
67 | Dave Rolsky E<lt>autarch@urth.orgE<gt> |
68 | |
69 | =head1 COPYRIGHT AND LICENSE |
70 | |
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71 | Copyright 2006-2009 by Infinity Interactive, Inc. |
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72 | |
73 | L<http://www.iinteractive.com> |
74 | |
75 | This library is free software; you can redistribute it and/or modify |
76 | it under the same terms as Perl itself. |
77 | |
78 | =pod |