I am not sure, but I think that Nr::CE::->setAWArgs(\@PK::NWKK::AA); here is equivalent to Nr::CE->setAWArgs(\@PK::NWKK::AA);. This is because an identifier followed by a double colon followed by nothing is usually equivalent to just the identifier as a bareword (without the double colon) except that it works under strict but warns if a package with the same name doesn't exist.