package Super::Class;
use constant FOO_IDX => NEXT_IDX(); # 0
use constant BAR_IDX => NEXT_IDX(); # 1
use constant BAZ_IDX => NEXT_IDX(); # 2

package Other::Sub::Class;
# need to wrap in BEGIN blocks so SUPER:: works in the use at
# compile time.
BEGIN {our @ISA = qw(Super::Class)};

use constant DIFFERENT_IDX => __PACKAGE__>SUPER::NEXT_IDX();
#now at 3, DIFFERENT THAN LAST TIME

package Sub::Class;
BEGIN {our @ISA = qw(Super::Class)};

use constant OTHER_IDX => __PACKAGE__>SUPER::NEXT_IDX();
#now at 4, DIFFERENT THAN LAST TIME!