Short answer:

• Empty parens mean "this function takes no arguments"
• No parens means that the arguments are not specified at all.

Unless you get into the whole morass that is parm specifications, just leave the parens off.

# Andy Lester  http://www.petdance.com  AIM:petdance
%_=split';','.; Perl ;@;st a;m;ker;p;not;o;hac;t;her;y;ju';
print map $_{$_}, split //,
'andy@petdance.com'