Extracting command line options directly into data members: each field marked with an @External annotation automatically becomes a command line option. Extracting the options values from the command line arguments, i.e., the "String[] args" parameter to main, into the field(s), requires a single method invocation: Introspector.extract(args, o1, o2, ...) where o1,o2, ... are the objects in which the fields annotated with @External.