NAME

       Mouse::Util::MetaRole - Apply roles to any metaclass, as well as the object base class

SYNOPSIS

         package MyApp::Mouse;

         use Mouse ();
         use Mouse::Exporter;
         use Mouse::Util::MetaRole;

         use MyApp::Role::Meta::Class;
         use MyApp::Role::Meta::Method::Constructor;
         use MyApp::Role::Object;

         Mouse::Exporter->setup_import_methods( also => 'Mouse' );

         sub init_meta {
             shift;
             my %args = @_;

             Mouse->init_meta(%args);

             Mouse::Util::MetaRole::apply_metaroles(
                 for             => $args{for_class},
                 class_metaroles => {
                     class       => ['MyApp::Role::Meta::Class'],
                     constructor => ['MyApp::Role::Meta::Method::Constructor'],
                 },
             );

             Mouse::Util::MetaRole::apply_base_class_roles(
                 for   => $args{for_class},
                 roles => ['MyApp::Role::Object'],
             );

             return $args{for_class}->meta();
         }

DESCRIPTION

       This utility module is designed to help authors of Mouse extensions write extensions that
       are able to cooperate with other Mouse extensions. To do this, you must write your
       extensions as roles, which can then be dynamically applied to the caller's metaclasses.

       This module makes sure to preserve any existing superclasses and roles already set for the
       meta objects, which means that any number of extensions can apply roles in any order.

USAGE

       It is very important that you only call this module's functions when your module is
       imported by the caller. The process of applying roles to the metaclass reinitializes the
       metaclass object, which wipes out any existing attributes already defined. However, as
       long as you do this when your module is imported, the caller should not have any
       attributes defined yet.

       The easiest way to ensure that this happens is to use Mouse::Exporter, which can generate
       the appropriate "init_meta" method for you, and make sure it is called when imported.

FUNCTIONS

       This module provides two functions.

   apply_metaroles( ... )
       This function will apply roles to one or more metaclasses for the specified class. It
       accepts the following parameters:

       •   for => $name

           This specifies the class or for which to alter the meta classes. This can be a package
           name, or an appropriate meta-object (a Mouse::Meta::Class or Mouse::Meta::Role).

       •   class_metaroles => \%roles

           This is a hash reference specifying which metaroles will be applied to the class
           metaclass and its contained metaclasses and helper classes.

           Each key should in turn point to an array reference of role names.

           It accepts the following keys:

           class
           attribute
           method
           constructor
           destructor
       •   role_metaroles => \%roles

           This is a hash reference specifying which metaroles will be applied to the role
           metaclass and its contained metaclasses and helper classes.

           It accepts the following keys:

           role
           method

   apply_base_class_roles( for => $class, roles => \@roles )
       This function will apply the specified roles to the object's base class.

SEE ALSO

       Moose::Util::MetaRole