Eh, no, that's not the only change. The big, fundamental change is that you are taking subs that are intended to be called as class methods, (Class -> subname), but call them as object methods ($obj = bless $ref, Class; $obj -> subname). Big difference. A difference that's about to be introduce around the point you copied and pasted from perlboot. The fact you don't quote the second argument to bless cause the strict error; the fact you call a class method as an object method gives you the funny animal name.