package Automobile;
sub CarType {die "Ought to be overridden!"}
__END__
package Car;
our @ISA = qw[Automobile];
sub CarType {"STRING1"}
__END__
package Truck;
our @ISA = qw[Automobile];
sub CarType {"STRING2"}
__END__
package ParkingLot;
$x = $automobile->CarType;