Mouse::Util::MetaRole(3pm)                 User Contributed Perl Documentation


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:

       o   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).

       o   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
       o   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

perl v5.38.0                      2023-07-26        Mouse::Util::MetaRole(3pm)