2 use Moose 'confess', 'blessed';
5 our $AUTHORITY = 'cpan:STEVAN';
10 my $policy = shift || return;
12 unless (Class::MOP::is_class_loaded($policy)) {
13 # otherwise require it ...
14 eval { Class::MOP::load_class($policy) };
15 confess "Could not load policy module '$policy' because : $@"
19 my $package = caller();
20 $package->can('meta') and
21 croak("'$package' already has a meta() method, this is very problematic");
23 my $metaclass = 'Moose::Meta::Class';
24 $metaclass = $policy->metaclass($package)
25 if $policy->can('metaclass');
29 # build options out of policy's constants
30 $policy->can($_) and $options{"$_"} = $policy->$_($package)
37 # create a meta object so we can install &meta
38 my $meta = $metaclass->initialize($package => %options);
39 $meta->add_method('meta' => sub {
40 # we must re-initialize so that it works as expected in
41 # subclasses, since metaclass instances are singletons, this is
42 # not really a big deal anyway.
43 $metaclass->initialize((blessed($_[0]) || $_[0]) => %options)
55 Moose::Policy - Moose-mounted police
61 use Moose::Policy 'Moose::Policy::FollowPBP';
64 has 'bar' => (is => 'rw', default => 'Foo::bar');
65 has 'baz' => (is => 'ro', default => 'Foo::baz');
67 # Foo now has (get, set)_bar methods as well as get_baz
71 This module allows you to specify your project-wide or even company-wide
74 Most all of Moose's features can be customized through the use of custom
75 metaclasses, however fiddling with the metaclasses can be hairy. Moose::Policy
76 removes most of that hairiness and makes it possible to cleanly contain
77 a set of meta-level customizations in one easy to use module.
79 This is still an release of this module and it should not be considered to
80 be complete by any means. It is very basic implemenation at this point and
81 will likely get more feature-full over time, as people request features.
82 So if you have a suggestion/need/idea, please speak up.
84 =head2 What is a meta-policy?
86 A meta-policy is a set of custom Moose metaclasses which can be used to
87 implement a number of customizations and restrictions on a particular
90 For instance, L<Moose::Policy::SingleInheritence> enforces that all
91 specified Moose classes can only use single inheritance. It does this
92 by trapping the call to C<superclasses> on the metaclass and only allowing
93 you to assign a single superclass.
95 The L<Moose::Policy::FollowPBP> policy changes the default behavior of
96 accessors to fit the recomendations found in Perl Best Practices.
100 =head2 Always load Moose::Policy first.
102 You B<must> put the following line of code:
104 use Moose::Policy 'My::Policy';
110 This is because Moose::Policy must be given the opportunity to set the
111 custom metaclass before Moose has set it's default metaclass. In fact, if
112 you try to set a Moose::Policy and there is a C<meta> method available,
113 not only will kittens die, but your program will too.
115 =head2 Policies are class scoped
117 You must repeat the policy for each class you want to use it. It is B<not>
118 inherited. This may change in the future, probably it will be a Moose::Policy
119 itself to allow Moose policies to be inherited.
123 A Policy is set by passing C<Moose::Polocy::import()> a package name. This
124 package is then queried for what metaclasses it should use. The possible
125 metaclass values are:
131 This defaults to C<Moose::Meta::Class>.
133 =item B<attribute_metaclass>
135 =item B<instance_metaclass>
137 =item B<method_metaclass>
141 For examples of what a Policy actually looks like see the examples in
142 C<Moose::Policy::> and the test suite. More docs to come on this later (probably
143 a cookbook or something).
155 As I said above, this is the first release and it is by no means feature complete.
156 There are a number of thoughts on the future direction of this module. Here are
157 some random thoughts on that, in no particular order.
161 =item Make set of policy roles
163 Roles are an excellent way to combine sets of behaviors together into one, and
164 custom metaclasses are actually better composed by roles then by inheritence.
165 The ideal situation is that this module will provide a set of roles which can be
166 used to compose your meta-policy with relative ease.
172 All complex software has bugs lurking in it, and this module is no
173 exception. If you find a bug please either email me, or add the bug
178 Stevan Little E<lt>stevan@iinteractive.comE<gt>
182 =head1 COPYRIGHT AND LICENSE
184 Copyright 2006-2007 by Infinity Interactive, Inc.
186 L<http://www.iinteractive.com>
188 This library is free software; you can redistribute it and/or modify
189 it under the same terms as Perl itself.