Moose::Role(3pm) User Contributed Perl Documentation Moose::Role(3pm)
NAME
Moose::Role - The Moose Role
VERSION
version 2.0603
SYNOPSIS
package Eq;
use Moose::Role; # automatically turns on strict and warnings
requires 'equal';
sub no_equal {
my ($self, $other) = @_;
!$self->equal($other);
}
# ... then in your classes
package Currency;
use Moose; # automatically turns on strict and warnings
with 'Eq';
sub equal {
my ($self, $other) = @_;
$self->as_float == $other->as_float;
}
# ... and also
package Comparator;
use Moose;
has compare_to => (
is => 'ro',
does => 'Eq',
handles => 'Eq',
);
# ... which allows
my $currency1 = Currency->new(...);
my $currency2 = Currency->new(...);
Comparator->new(compare_to => $currency1)->equal($currency2);
DESCRIPTION
The concept of roles is documented in Moose::Manual::Roles. This document serves as API documentation.
EXPORTED FUNCTIONS
Moose::Role currently supports all of the functions that Moose exports, but differs slightly in how some items are handled (see "CAVEATS"
below for details).
Moose::Role also offers two role-specific keyword exports:
requires (@method_names)
Roles can require that certain methods are implemented by any class which "does" the role.
Note that attribute accessors also count as methods for the purposes of satisfying the requirements of a role.
excludes (@role_names)
Roles can "exclude" other roles, in effect saying "I can never be combined with these @role_names". This is a feature which should not
be used lightly.
unimport
Moose::Role offers a way to remove the keywords it exports, through the "unimport" method. You simply have to say "no Moose::Role" at the
bottom of your code for this to work.
METACLASS
When you use Moose::Role, you can specify traits which will be applied to your role metaclass:
use Moose::Role -traits => 'My::Trait';
This is very similar to the attribute traits feature. When you do this, your class's "meta" object will have the specified traits applied
to it. See "Metaclass and Trait Name Resolution" in Moose for more details.
APPLYING ROLES
In addition to being applied to a class using the 'with' syntax (see Moose::Manual::Roles) and using the Moose::Util 'apply_all_roles'
method, roles may also be applied to an instance of a class using Moose::Util 'apply_all_roles' or the role's metaclass:
MyApp::Test::SomeRole->meta->apply( $instance );
Doing this creates a new, mutable, anonymous subclass, applies the role to that, and reblesses. In a debugger, for example, you will see
class names of the form " Moose::Meta::Class::__ANON__::SERIAL::6 ", which means that doing a 'ref' on your instance may not return what
you expect. See Moose::Object for 'DOES'.
Additional params may be added to the new instance by providing 'rebless_params'. See Moose::Meta::Role::Application::ToInstance.
CAVEATS
Role support has only a few caveats:
o Roles cannot use the "extends" keyword; it will throw an exception for now. The same is true of the "augment" and "inner" keywords
(not sure those really make sense for roles). All other Moose keywords will be deferred so that they can be applied to the consuming
class.
o Role composition does its best to not be order-sensitive when it comes to conflict resolution and requirements detection. However, it
is order-sensitive when it comes to method modifiers. All before/around/after modifiers are included whenever a role is composed into a
class, and then applied in the order in which the roles are used. This also means that there is no conflict for before/around/after
modifiers.
In most cases, this will be a non-issue; however, it is something to keep in mind when using method modifiers in a role. You should
never assume any ordering.
BUGS
See "BUGS" in Moose for details on reporting bugs.
AUTHOR
Moose is maintained by the Moose Cabal, along with the help of many contributors. See "CABAL" in Moose and "CONTRIBUTORS" in Moose for
details.
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 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.
perl v5.14.2 2012-06-28 Moose::Role(3pm)