gistfile1.pl

package CD;
use Moose;
use MooseX::PassableBuilder;
use File::Slurp 'slurp';

has title => (
    is       => 'ro',
    isa      => 'Str',
    required => 1,
);

has artist => (
    is       => 'ro',
    isa      => 'Str',
    required => 1,
);

has artwork => (
    traits    => ['PassableBuilder'],
    is        => 'ro',
    isa       => 'Str',
    lazy      => 1,
    builder   => '_build_artwork',
    predicate => 'has_artwork',
);

sub _build_artwork {
    my $self     = shift;
    my $no_value = shift;

    my $title   = $self->title;
    my $artist  = $self->artist;

    my $file = "/music/$artist/$title.jpg";

    return $no_value if !-r $file;
    return slurp $file;
}