=pod
=begin testing-SETUP
BEGIN {
eval 'use Test::Output;';
if ($@) {
diag 'Test::Output is required for this test';
ok(1);
exit 0;
}
}
=end testing-SETUP
=head1 NAME
Moose::Cookbook::Extending::Recipe2 - Providing a role for the base object class
=head1 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;
after 'BUILDALL' => sub {
my $self = shift;
warn "Made a new " . ( ref $self ) . " object\n";
};
=head1 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 L<Moose::Exporter> and
L<Moose::Util::MetaRole>, we ensure that when a module does C<S<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 C<import> method in the C<MooseX::Debugging> package. Since we
are not actually exporting anything, we do not pass C<setup_import_methods>
any parameters related to exports, but we need to have an C<import> method to
ensure that our C<init_meta> method is called. The C<init_meta> is created by
C<setup_import_methods> for us, since we passed the C<base_class_roles>
parameter. The generated C<init_meta> will in turn call
L<Moose::Util::MetaRole::apply_base_class_roles|Moose::Util::MetaRole/apply_base_class_roles>.
=head1 AUTHOR
Dave Rolsky E<lt>autarch@urth.orgE<gt>
=head1 COPYRIGHT AND LICENSE
Copyright 2009 by Infinity Interactive, Inc.
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=begin testing
{
package Debugged;
use Moose;
MooseX::Debugging->import;
}
stderr_is(
sub { Debugged->new },
"Made a new Debugged object\n",
'got expected output from debugging role'
);
=end testing
=cut