package Moose::Role;
use strict;
use warnings;
use Scalar::Util 'blessed';
use Carp 'croak';
use Sub::Exporter;
our $VERSION = '1.00';
$VERSION = eval $VERSION;
our $AUTHORITY = 'cpan:STEVAN';
use Moose ();
use Moose::Util ();
use Moose::Exporter;
use Moose::Meta::Role;
use Moose::Util::TypeConstraints;
sub extends {
croak "Roles do not support 'extends' (you can use 'with' to specialize a role)";
}
sub with {
Moose::Util::apply_all_roles( shift, @_ );
}
sub requires {
my $meta = shift;
croak "Must specify at least one method" unless @_;
$meta->add_required_methods(@_);
}
sub excludes {
my $meta = shift;
croak "Must specify at least one role" unless @_;
$meta->add_excluded_roles(@_);
}
sub has {
my $meta = shift;
my $name = shift;
croak 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
$meta->add_attribute( $_, %options ) for @$attrs;
}
sub _add_method_modifier {
my $type = shift;
my $meta = shift;
my $code = pop @_;
for (@_) {
croak "Roles do not currently support "
. ref($_)
. " references for $type method modifiers"
if ref $_;
my $add_method = "add_${type}_method_modifier";
$meta->$add_method( $_, $code );
}
}
sub before { _add_method_modifier('before', @_) }
sub after { _add_method_modifier('after', @_) }
sub around { _add_method_modifier('around', @_) }
# see Moose.pm for discussion
sub super {
return unless $Moose::SUPER_BODY;
$Moose::SUPER_BODY->(@Moose::SUPER_ARGS);
}
sub override {
my $meta = shift;
my ( $name, $code ) = @_;
$meta->add_override_method_modifier( $name, $code );
}
sub inner {
croak "Roles cannot support 'inner'";
}
sub augment {
croak "Roles cannot support 'augment'";
}
Moose::Exporter->setup_import_methods(
with_meta => [
qw( with requires excludes has before after around override )
],
as_is => [
qw( extends super inner augment ),
\&Carp::confess,
\&Scalar::Util::blessed,
],
);
sub init_meta {
shift;
my %args = @_;
my $role = $args{for_class};
unless ($role) {
require Moose;
Moose->throw_error("Cannot call init_meta without specifying a for_class");
}
my $metaclass = $args{metaclass} || "Moose::Meta::Role";
# make a subtype for each Moose class
role_type $role unless find_type_constraint($role);
# FIXME copy from Moose.pm
my $meta;
if ($role->can('meta')) {
$meta = $role->meta();
unless ( blessed($meta) && $meta->isa('Moose::Meta::Role') ) {
require Moose;
Moose->throw_error("You already have a &meta function, but it does not return a Moose::Meta::Role");
}
}
else {
$meta = $metaclass->initialize($role);
$meta->add_method(
'meta' => sub {
# re-initialize so it inherits properly
$metaclass->initialize( ref($_[0]) || $_[0] );
}
);
}
return $meta;
}
1;
__END__
=pod
=head1 NAME
Moose::Role - The Moose Role
=head1 SYNOPSIS
package Eq;
use Moose::Role; # automatically turns on strict and warnings
requires 'equal';
sub no_equal {
my ($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;
}
=head1 DESCRIPTION
The concept of roles is documented in L<Moose::Manual::Roles>. This document
serves as API documentation.
=head1 EXPORTED FUNCTIONS
Moose::Role currently supports all of the functions that L<Moose> exports, but
differs slightly in how some items are handled (see L</CAVEATS> below for
details).
Moose::Role also offers two role-specific keyword exports:
=over 4
=item B<requires (@method_names)>
Roles can require that certain methods are implemented by any class which
C<does> the role.
Note that attribute accessors also count as methods for the purposes
of satisfying the requirements of a role.
=item B<excludes (@role_names)>
Roles can C<exclude> other roles, in effect saying "I can never be combined
with these C<@role_names>". This is a feature which should not be used
lightly.
=back
=head2 B<unimport>
Moose::Role offers a way to remove the keywords it exports, through the
C<unimport> method. You simply have to say C<no Moose::Role> at the bottom of
your code for this to work.
=head2 B<< Moose::Role->init_meta(for_class => $role, metaclass => $metaclass) >>
The C<init_meta> method sets up the metaclass object for the role
specified by C<for_class>. It also injects a a C<meta> accessor into
the role so you can get at this object.
The default metaclass is L<Moose::Meta::Role>. You can specify an
alternate metaclass with the C<metaclass> parameter.
=head1 METACLASS
When you use Moose::Role, you can specify which metaclass to use:
use Moose::Role -metaclass => 'My::Meta::Role';
You can also 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 C<meta> object will have the specified traits
applied to it. See L<Moose/Metaclass and Trait Name Resolution> for more
details.
=head1 APPLYING ROLES
In addition to being applied to a class using the 'with' syntax (see
L<Moose::Manual::Roles>) and using the L<Moose::Util> 'apply_all_roles'
method, roles may also be applied to an instance of a class using
L<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 C< Class::MOP::Class::__ANON__::SERIAL::6 >, which means that doing a 'ref'
on your instance may not return what you expect. See L<Moose::Object> for 'DOES'.
Additional params may be added to the new instance by providing 'rebless_params'.
See L<Moose::Meta::Role::Application::ToInstance>.
=head1 CAVEATS
Role support has only a few caveats:
=over 4
=item *
Roles cannot use the C<extends> keyword; it will throw an exception for now.
The same is true of the C<augment> and C<inner> keywords (not sure those
really make sense for roles). All other Moose keywords will be I<deferred>
so that they can be applied to the consuming class.
=item *
Role composition does its best to B<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.
=back
=head1 BUGS
See L<Moose/BUGS> for details on reporting bugs.
=head1 AUTHOR
Stevan Little E<lt>stevan@iinteractive.comE<gt>
Christian Hansen E<lt>chansen@cpan.orgE<gt>
=head1 COPYRIGHT AND LICENSE
Copyright 2006-2010 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut