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.\" ========================================================================
.\"
.IX Title "Mouse::Util::MetaRole 3pm"
.TH Mouse::Util::MetaRole 3pm 2024-03-07 "perl v5.38.2" "User Contributed Perl Documentation"
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.SH NAME
Mouse::Util::MetaRole \- Apply roles to any metaclass, as well as the object base class
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  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 => \*(AqMouse\*(Aq );
\&
\&  sub init_meta {
\&      shift;
\&      my %args = @_;
\&
\&      Mouse\->init_meta(%args);
\&
\&      Mouse::Util::MetaRole::apply_metaroles(
\&          for             => $args{for_class},
\&          class_metaroles => {
\&              class       => [\*(AqMyApp::Role::Meta::Class\*(Aq],
\&              constructor => [\*(AqMyApp::Role::Meta::Method::Constructor\*(Aq],
\&          },
\&      );
\&
\&      Mouse::Util::MetaRole::apply_base_class_roles(
\&          for   => $args{for_class},
\&          roles => [\*(AqMyApp::Role::Object\*(Aq],
\&      );
\&
\&      return $args{for_class}\->meta();
\&  }
.Ve
.SH DESCRIPTION
.IX Header "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.
.PP
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.
.SH USAGE
.IX Header "USAGE"
\&\fBIt is very important that you only call this module's functions when
your module is imported by the caller\fR. 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.
.PP
The easiest way to ensure that this happens is to use
Mouse::Exporter, which can generate the appropriate \f(CW\*(C`init_meta\*(C'\fR
method for you, and make sure it is called when imported.
.SH FUNCTIONS
.IX Header "FUNCTIONS"
This module provides two functions.
.SS "apply_metaroles( ... )"
.IX Subsection "apply_metaroles( ... )"
This function will apply roles to one or more metaclasses for the
specified class. It accepts the following parameters:
.IP \(bu 4
for => \f(CW$name\fR
.Sp
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).
.IP \(bu 4
class_metaroles => \e%roles
.Sp
This is a hash reference specifying which metaroles will be applied to the
class metaclass and its contained metaclasses and helper classes.
.Sp
Each key should in turn point to an array reference of role names.
.Sp
It accepts the following keys:
.RS 4
.IP class 8
.IX Item "class"
.PD 0
.IP attribute 8
.IX Item "attribute"
.IP method 8
.IX Item "method"
.IP constructor 8
.IX Item "constructor"
.IP destructor 8
.IX Item "destructor"
.RE
.RS 4
.RE
.IP \(bu 4
.PD
role_metaroles => \e%roles
.Sp
This is a hash reference specifying which metaroles will be applied to the
role metaclass and its contained metaclasses and helper classes.
.Sp
It accepts the following keys:
.RS 4
.IP role 8
.IX Item "role"
.PD 0
.IP method 8
.IX Item "method"
.RE
.RS 4
.RE
.PD
.ie n .SS "apply_base_class_roles( for => $class, roles => \e@roles )"
.el .SS "apply_base_class_roles( for => \f(CW$class\fP, roles => \e@roles )"
.IX Subsection "apply_base_class_roles( for => $class, roles => @roles )"
This function will apply the specified roles to the object's base class.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Moose::Util::MetaRole