Commit | Line | Data |
6fa0a13f |
1 | |
2 | =pod |
3 | |
4 | =head1 NAME |
5 | |
6 | Moose::Cookbook::Extending::Recipe2 - Acting like Moose.pm and providing sugar Moose-style |
7 | |
8 | =head1 SYNOPSIS |
9 | |
10 | package MyApp::Mooseish; |
11 | |
12 | use strict; |
13 | use warnings; |
14 | |
15 | our @EXPORT = qw( has_table ); |
16 | |
17 | use base 'Exporter'; |
18 | use Class::MOP; |
19 | use Moose (); |
20 | |
21 | sub import { |
22 | my $caller = caller(); |
23 | |
24 | return if $caller eq 'main'; |
25 | |
26 | Moose::init_meta( $caller, |
27 | undef, # object base class |
28 | 'MyApp::Meta::Class', |
29 | ); |
30 | |
31 | Moose->import( { into => $caller }, @_ ); |
32 | |
33 | __PACKAGE__->export_to_level( 1, @_ ); |
34 | } |
35 | |
36 | sub unimport { |
37 | my $caller = caller(); |
38 | |
39 | no strict 'refs'; |
40 | foreach my $name (@EXPORT) { |
41 | if ( defined &{ $caller . '::' . $name } ) { |
42 | my $keyword = \&{ $caller . '::' . $name }; |
43 | |
44 | my ($pkg_name) = Class::MOP::get_code_info($keyword); |
45 | |
46 | next if $pkg_name ne __PACKAGE__; |
47 | |
48 | delete ${ $caller . '::' }{$name}; |
49 | } |
50 | } |
51 | |
52 | Moose::unimport( { into_level => 1 } ); |
53 | } |
54 | |
55 | sub has_table { |
56 | my $caller = caller(); |
57 | |
58 | $caller->meta()->table(shift); |
59 | } |
60 | |
61 | =head1 DESCRIPTION |
62 | |
63 | The code above shows what it takes to provide an import-based |
64 | interface just like C<Moose.pm>. |
65 | |
66 | Given the above code, you can now replace all instances of C<use |
67 | Moose> with C<use MyApp::Mooseish>. Similarly, C<no Moose> is now |
68 | replaced with C<no MyApp::Mooseish>. |
69 | |
70 | =head1 WARNING |
71 | |
72 | This recipe covers a fairly undocumented and ugly part of Moose, and |
73 | the techniques described here may be deprecated in a future |
74 | release. If this happens, there will be plenty of warning, as a number |
75 | of C<MooseX> modules on CPAN already use these techniques. |
76 | |
77 | =head1 HOW IT IS USED |
78 | |
79 | The purpose of all this code is to provide a Moose-like |
80 | interface. Here's what it would look like in actual use: |
81 | |
82 | package MyApp::User; |
83 | |
84 | use MyApp::Mooseish; |
85 | |
86 | has_table 'User'; |
87 | |
88 | has 'username'; |
89 | has 'password'; |
90 | |
91 | sub login { ... } |
92 | |
93 | no MyApp::Mooseish; |
94 | |
95 | All of the normal Moose sugar (C<has()>, C<with()>, etc) is available |
96 | when you C<use MyApp::Mooseish>. |
97 | |
98 | =head1 DISSECTION |
99 | |
100 | The first bit of magic is the call to C<Moose::init_meta()>. What this |
101 | does is create a metaclass for the specified class. Normally, this is |
102 | called by C<Moose.pm> in its own C<import()> method. However, we can |
103 | call it first in order to provide an alternate metaclass class. We |
104 | could also provide an alternate base object class to replace |
105 | C<Moose::Object> (see L<Moose::Cookbook::Extending::Recipe1> for an |
106 | example). |
107 | |
108 | The C<Moose::init_meta()> call takes three parameters. The first is |
109 | the class for which we are initializing a metaclass object. The second |
110 | is the base object, which is L<Moose::Object> by default. The third |
111 | argument is the metaclass class, which is C<Moose::Meta::Class> by |
112 | default. |
113 | |
114 | The next bit of magic is this: |
115 | |
116 | Moose->import( { into => $caller } ); |
117 | |
118 | This use of "into" is actually part of the C<Sub::Exporter> API, which |
119 | C<Moose.pm> uses internally to export things like C<has()> and |
120 | C<extends()>. |
121 | |
122 | Finally, we call C<< __PACKAGE__->export_to_level() >>. This method |
123 | actually comes from C<Exporter>. |
124 | |
125 | This is all a bit fragile since it doesn't stack terribly well. You |
126 | can basically only have one Moose-alike module. This may be fixed in |
127 | the still-notional C<MooseX::Exporter> module someday. |
128 | |
129 | The C<unimport()> subroutine is basically a copy of the C<unimport()> |
130 | from C<Moose.pm>. You can copy this verbatim into your code. Again, |
131 | this doesn't stack well. |
132 | |
133 | Finally, we have our C<has_table()> subroutine. This provides a bit of |
134 | sugar that looks a lot like C<has()>. |
135 | |
136 | =head1 AUTHOR |
137 | |
138 | Dave Rolsky E<lt>autarch@urth.orgE<gt> |
139 | |
140 | =head1 COPYRIGHT AND LICENSE |
141 | |
142 | Copyright 2006-2008 by Infinity Interactive, Inc. |
143 | |
144 | L<http://www.iinteractive.com> |
145 | |
146 | This library is free software; you can redistribute it and/or modify |
147 | it under the same terms as Perl itself. |
148 | |
149 | =pod |