package Person;
    use Carp;
    our $AUTOLOAD;  # it's a package global

    my %fields = (
        name        => undef,
        age         => undef,
        peers       => undef,
    );

    sub new {
        my $class = shift;
        my $self  = {
            _permitted => \%fields,
            %fields,
        };
        bless $self, $class;
        return $self;
    }