moose::cookbook::extending::debugging_baseclassrole(3) [mojave man page]

Moose::Cookbook::Extending::Debugging_BaseClassRole(3)	User Contributed Perl Documentation Moose::Cookbook::Extending::Debugging_BaseClassRole(3)

NAME

       Moose::Cookbook::Extending::Debugging_BaseClassRole - Providing a role for the base object class

VERSION

       version 2.1202

SYNOPSIS

	 package MooseX::Debugging;

	 use Moose::Exporter;

	 Moose::Exporter->setup_import_methods(
	     base_class_roles => ['MooseX::Debugging::Role::Object'],
	 );

	 package MooseX::Debugging::Role::Object;

	 use Moose::Role;

	 sub BUILD {}
	 after BUILD => sub {
	     my $self = shift;

	     warn "Made a new " . ( ref $self ) . " object
";
	 };

DESCRIPTION

       In this example, we provide a role for the base object class that adds some simple debugging output. Every time an object is created, it
       spits out a warning saying what type of object it was.

       Obviously, a real debugging role would do something more interesting, but this recipe is all about how we apply that role.

       In this case, with the combination of Moose::Exporter and Moose::Util::MetaRole, we ensure that when a module does "use MooseX::Debugging",
       it automatically gets the debugging role applied to its base object class.

       There are a few pieces of code worth looking at more closely.

	 Moose::Exporter->setup_import_methods(
	     base_class_roles => ['MooseX::Debugging::Role::Object'],
	 );

       This creates an "import" method in the "MooseX::Debugging" package. Since we are not actually exporting anything, we do not pass
       "setup_import_methods" any parameters related to exports, but we need to have an "import" method to ensure that our "init_meta" method is
       called. The "init_meta" is created by "setup_import_methods" for us, since we passed the "base_class_roles" parameter. The generated
       "init_meta" will in turn call Moose::Util::MetaRole::apply_base_class_roles.

	 sub BUILD {}
	 after BUILD => sub {
	     ...
	 };

       Due to the way role composition currently works, if the class that a role is composed into contains a "BUILD" method, then that will
       override the "BUILD" method in any roles it composes, which is typically not what you want. Using a method modifier on "BUILD" avoids this
       issue, since method modifiers compose together rather than being overridden. Method modifiers require that a method exists in order to
       wrap, however, so we also provide a stub method to wrap if no "BUILD" method exists in the class.

AUTHORS

       o   Stevan Little <stevan.little@iinteractive.com>

       o   Dave Rolsky <autarch@urth.org>

       o   Jesse Luehrs <doy@tozt.net>

       o   Shawn M Moore <code@sartak.org>

       o   XXXX XXX'XX (Yuval Kogman) <nothingmuch@woobling.org>

       o   Karen Etheridge <ether@cpan.org>

       o   Florian Ragwitz <rafl@debian.org>

       o   Hans Dieter Pearcey <hdp@weftsoar.net>

       o   Chris Prather <chris@prather.org>

       o   Matt S Trout <mst@shadowcat.co.uk>

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.

perl v5.18.2							    2014-01-19		    Moose::Cookbook::Extending::Debugging_BaseClassRole(3)

Moose::Util::MetaRole(3)				User Contributed Perl Documentation				  Moose::Util::MetaRole(3)

NAME

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

VERSION

       version 2.1202

SYNOPSIS

	 package MyApp::Moose;

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

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

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

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

	     Moose->init_meta(%args);

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

	     Moose::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 Moose extensions write extensions that are able to cooperate with other Moose
       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

       The easiest way to use this module is through Moose::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 will return a new metaclass object for the class or
       role passed in the "for" parameter.

       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
	   Moose::Meta::Class or Moose::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
	   wrapped_method
	   instance
	   constructor
	   destructor
	   error
       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
	   attribute
	   method
	   required_method
	   conflicting_method
	   application_to_class
	   application_to_role
	   application_to_instance
	   application_role_summation
	   applied_attribute

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

BUGS

       See "BUGS" in Moose for details on reporting bugs.

AUTHORS

       o   Stevan Little <stevan.little@iinteractive.com>

       o   Dave Rolsky <autarch@urth.org>

       o   Jesse Luehrs <doy@tozt.net>

       o   Shawn M Moore <code@sartak.org>

       o   XXXX XXX'XX (Yuval Kogman) <nothingmuch@woobling.org>

       o   Karen Etheridge <ether@cpan.org>

       o   Florian Ragwitz <rafl@debian.org>

       o   Hans Dieter Pearcey <hdp@weftsoar.net>

       o   Chris Prather <chris@prather.org>

       o   Matt S Trout <mst@shadowcat.co.uk>

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.

perl v5.18.2							    2014-01-19						  Moose::Util::MetaRole(3)