I presume you got an error with use vars because you had:
use vars (@ISA @EXPORT @EXPORT_OK);
instead of:
use vars qw(@ISA @EXPORT @EXPORT_OK);
In the former, you are referring to variables that you have not declared yet. In the latter, you have a list of strings, each one of which happens to be the name of a variable. Examples in the documentation show the proper way to use vars: vars, strict
Aha! You were on the right track with your post. There was something wrong with my qw, but I hadn't omitted it, I had accidentally put commas between the names,like so: