in reply to A question of style
I generally only use the ampersand when I'm calling a subroutine via a reference. The rest of the time, I follow perlstyle and put parenthesis on user-defined subroutines, even when I pass an empty argument list.
Idiomatic Perl is good, but I haven't seen enough people using the &subname-passes-@_ behavior often enough to use it regularly.
Sometimes, I even use $sub_ref->(), but that's just silly.