well 'use base qw(Exporter)' means that you inherit the functionality of exporter. In short you are writing another Exporter. Also the published syntax is 'use base LIST' where LIST is a list of strings; so technically 'use base (Exporter)' is not correct and I don't use it (it works if the bareword can be interpreted as a string which means you did not 'use strict;' naughty you! ;)

'use Exporter' means that you will let users of your module "import" some symbols in their namespace. Best practices imply that your module is not OO (or should not be...).

hth --stephan