sub new {
    my $class = shift;
    return undef if ref $class;

    my ($first, $second) = @_;

    my $self = sub {
        my $var = shift;
        my ($mode, $newval) = @_;

        if ($var == 0) {
            return $mode ? $first = $newval : $first;
        } elsif ($var == 1) {
            return $mode ? $second = $newval : $second;
        }
        return undef;
    };
    bless $self, $class;

    return $self;
}