192 lines
3.9 KiB
Plaintext
192 lines
3.9 KiB
Plaintext
# PODNAME: Moose::Cookbook::Roles::ApplicationToInstance
|
|
# ABSTRACT: Applying a role to an object instance
|
|
|
|
__END__
|
|
|
|
=pod
|
|
|
|
=encoding UTF-8
|
|
|
|
=head1 NAME
|
|
|
|
Moose::Cookbook::Roles::ApplicationToInstance - Applying a role to an object instance
|
|
|
|
=head1 VERSION
|
|
|
|
version 2.2207
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
package MyApp::Role::Job::Manager;
|
|
|
|
use List::Util qw( first );
|
|
|
|
use Moose::Role;
|
|
|
|
has 'employees' => (
|
|
is => 'rw',
|
|
isa => 'ArrayRef[Employee]',
|
|
);
|
|
|
|
sub assign_work {
|
|
my $self = shift;
|
|
my $work = shift;
|
|
|
|
my $employee = first { !$_->has_work } @{ $self->employees };
|
|
|
|
die 'All my employees have work to do!' unless $employee;
|
|
|
|
$employee->work($work);
|
|
}
|
|
|
|
package main;
|
|
|
|
my $lisa = Employee->new( name => 'Lisa' );
|
|
MyApp::Role::Job::Manager->meta->apply($lisa);
|
|
|
|
my $homer = Employee->new( name => 'Homer' );
|
|
my $bart = Employee->new( name => 'Bart' );
|
|
my $marge = Employee->new( name => 'Marge' );
|
|
|
|
$lisa->employees( [ $homer, $bart, $marge ] );
|
|
$lisa->assign_work('mow the lawn');
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
In this recipe, we show how a role can be applied to an object. In
|
|
this specific case, we are giving an employee managerial
|
|
responsibilities.
|
|
|
|
Applying a role to an object is simple. The L<Moose::Meta::Role>
|
|
object provides an C<apply> method. This method will do the right
|
|
thing when given an object instance.
|
|
|
|
MyApp::Role::Job::Manager->meta->apply($lisa);
|
|
|
|
We could also use the C<apply_all_roles> function from L<Moose::Util>.
|
|
|
|
apply_all_roles( $person, MyApp::Role::Job::Manager->meta );
|
|
|
|
The main advantage of using C<apply_all_roles> is that it can be used
|
|
to apply more than one role at a time.
|
|
|
|
We could also pass parameters to the role we're applying:
|
|
|
|
MyApp::Role::Job::Manager->meta->apply(
|
|
$lisa,
|
|
-alias => { assign_work => 'get_off_your_lazy_behind' },
|
|
);
|
|
|
|
We saw examples of how method exclusion and alias working in
|
|
L<Moose::Cookbook::Roles::Restartable_AdvancedComposition>.
|
|
|
|
=begin testing-SETUP
|
|
|
|
{
|
|
# Not in the recipe, but needed for writing tests.
|
|
package Employee;
|
|
|
|
use Moose;
|
|
|
|
has 'name' => (
|
|
is => 'ro',
|
|
isa => 'Str',
|
|
required => 1,
|
|
);
|
|
|
|
has 'work' => (
|
|
is => 'rw',
|
|
isa => 'Str',
|
|
predicate => 'has_work',
|
|
);
|
|
}
|
|
|
|
=end testing-SETUP
|
|
|
|
=head1 CONCLUSION
|
|
|
|
Applying a role to an object instance is a useful tool for adding
|
|
behavior to existing objects. In our example, it is effective used to
|
|
model a promotion.
|
|
|
|
It can also be useful as a sort of controlled monkey-patching for
|
|
existing code, particularly non-Moose code. For example, you could
|
|
create a debugging role and apply it to an object at runtime.
|
|
|
|
=begin testing
|
|
|
|
{
|
|
my $lisa = Employee->new( name => 'Lisa' );
|
|
MyApp::Role::Job::Manager->meta->apply($lisa);
|
|
|
|
my $homer = Employee->new( name => 'Homer' );
|
|
my $bart = Employee->new( name => 'Bart' );
|
|
my $marge = Employee->new( name => 'Marge' );
|
|
|
|
$lisa->employees( [ $homer, $bart, $marge ] );
|
|
$lisa->assign_work('mow the lawn');
|
|
|
|
ok( $lisa->does('MyApp::Role::Job::Manager'),
|
|
'lisa now does the manager role' );
|
|
|
|
is( $homer->work, 'mow the lawn',
|
|
'homer was assigned a task by lisa' );
|
|
}
|
|
|
|
=end testing
|
|
|
|
=head1 AUTHORS
|
|
|
|
=over 4
|
|
|
|
=item *
|
|
|
|
Stevan Little <stevan@cpan.org>
|
|
|
|
=item *
|
|
|
|
Dave Rolsky <autarch@urth.org>
|
|
|
|
=item *
|
|
|
|
Jesse Luehrs <doy@cpan.org>
|
|
|
|
=item *
|
|
|
|
Shawn M Moore <sartak@cpan.org>
|
|
|
|
=item *
|
|
|
|
יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>
|
|
|
|
=item *
|
|
|
|
Karen Etheridge <ether@cpan.org>
|
|
|
|
=item *
|
|
|
|
Florian Ragwitz <rafl@debian.org>
|
|
|
|
=item *
|
|
|
|
Hans Dieter Pearcey <hdp@cpan.org>
|
|
|
|
=item *
|
|
|
|
Chris Prather <chris@prather.org>
|
|
|
|
=item *
|
|
|
|
Matt S Trout <mstrout@cpan.org>
|
|
|
|
=back
|
|
|
|
=head1 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.
|
|
|
|
=cut
|