phpman > perldoc > Moose::Role

NAME
    Moose::Role - The Moose Role

VERSION
    version 2.2200

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.

  no Moose::Role
    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.

    All role metaclasses (note, not the role itself) extend Moose::Meta::Role. You can test if a
    package is a role or not using "is_role" in Moose::Util.

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:

    *   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.

    *   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.

AUTHORS
    *   Stevan Little <stevan AT cpan.org>

    *   Dave Rolsky <autarch AT urth.org>

    *   Jesse Luehrs <doy AT cpan.org>

    *   Shawn M Moore <sartak AT cpan.org>

    *   יובל קוג'מן (Yuval Kogman) <nothingmuch AT woobling.org>

    *   Karen Etheridge <ether AT cpan.org>

    *   Florian Ragwitz <rafl AT debian.org>

    *   Hans Dieter Pearcey <hdp AT cpan.org>

    *   Chris Prather <chris AT prather.org>

    *   Matt S Trout <mstrout AT cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2006 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.