1Moose::Role(3)        User Contributed Perl Documentation       Moose::Role(3)
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NAME

6       Moose::Role - The Moose Role
7

SYNOPSIS

9         package Eq;
10         use Moose::Role; # automatically turns on strict and warnings
11
12         requires 'equal';
13
14         sub no_equal {
15             my ($self, $other) = @_;
16             !$self->equal($other);
17         }
18
19         # ... then in your classes
20
21         package Currency;
22         use Moose; # automatically turns on strict and warnings
23
24         with 'Eq';
25
26         sub equal {
27             my ($self, $other) = @_;
28             $self->as_float == $other->as_float;
29         }
30

DESCRIPTION

32       The concept of roles is documented in Moose::Manual::Roles. This
33       document serves as API documentation.
34

EXPORTED FUNCTIONS

36       Moose::Role currently supports all of the functions that Moose exports,
37       but differs slightly in how some items are handled (see "CAVEATS" below
38       for details).
39
40       Moose::Role also offers two role-specific keyword exports:
41
42       requires (@method_names)
43           Roles can require that certain methods are implemented by any class
44           which "does" the role.
45
46           Note that attribute accessors also count as methods for the
47           purposes of satisfying the requirements of a role.
48
49       excludes (@role_names)
50           Roles can "exclude" other roles, in effect saying "I can never be
51           combined with these @role_names". This is a feature which should
52           not be used lightly.
53
54   unimport
55       Moose::Role offers a way to remove the keywords it exports, through the
56       "unimport" method. You simply have to say "no Moose::Role" at the
57       bottom of your code for this to work.
58
59   Moose::Role->init_meta(for_class => $role, metaclass => $metaclass)
60       The "init_meta" method sets up the metaclass object for the role
61       specified by "for_class". It also injects a a "meta" accessor into the
62       role so you can get at this object.
63
64       The default metaclass is Moose::Meta::Role. You can specify an
65       alternate metaclass with the "metaclass" parameter.
66

METACLASS

68       When you use Moose::Role, you can specify which metaclass to use:
69
70           use Moose::Role -metaclass => 'My::Meta::Role';
71
72       You can also specify traits which will be applied to your role
73       metaclass:
74
75           use Moose::Role -traits => 'My::Trait';
76
77       This is very similar to the attribute traits feature. When you do this,
78       your class's "meta" object will have the specified traits applied to
79       it. See "Metaclass and Trait Name Resolution" in Moose for more
80       details.
81

APPLYING ROLES

83       In addition to being applied to a class using the 'with' syntax (see
84       Moose::Manual::Roles) and using the Moose::Util 'apply_all_roles'
85       method, roles may also be applied to an instance of a class using
86       Moose::Util 'apply_all_roles' or the role's metaclass:
87
88          MyApp::Test::SomeRole->meta->apply( $instance );
89
90       Doing this creates a new, mutable, anonymous subclass, applies the role
91       to that, and reblesses. In a debugger, for example, you will see class
92       names of the form " Class::MOP::Class::__ANON__::SERIAL::6 ", which
93       means that doing a 'ref' on your instance may not return what you
94       expect. See Moose::Object for 'DOES'.
95
96       Additional params may be added to the new instance by providing
97       'rebless_params'.  See Moose::Meta::Role::Application::ToInstance.
98

CAVEATS

100       Role support has only a few caveats:
101
102       ·   Roles cannot use the "extends" keyword; it will throw an exception
103           for now.  The same is true of the "augment" and "inner" keywords
104           (not sure those really make sense for roles). All other Moose
105           keywords will be deferred so that they can be applied to the
106           consuming class.
107
108       ·   Role composition does its best to not be order-sensitive when it
109           comes to conflict resolution and requirements detection. However,
110           it is order-sensitive when it comes to method modifiers. All
111           before/around/after modifiers are included whenever a role is
112           composed into a class, and then applied in the order in which the
113           roles are used. This also means that there is no conflict for
114           before/around/after modifiers.
115
116           In most cases, this will be a non-issue; however, it is something
117           to keep in mind when using method modifiers in a role. You should
118           never assume any ordering.
119

BUGS

121       See "BUGS" in Moose for details on reporting bugs.
122

AUTHOR

124       Stevan Little <stevan@iinteractive.com>
125
126       Christian Hansen <chansen@cpan.org>
127

129       Copyright 2006-2010 by Infinity Interactive, Inc.
130
131       <http://www.iinteractive.com>
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133       This library is free software; you can redistribute it and/or modify it
134       under the same terms as Perl itself.
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138perl v5.12.2                      2010-08-28                    Moose::Role(3)
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