RubyModule parentPackage, String sym) {
IRubyObject packageNameObj = parentPackage.fastGetInstanceVariable("@package_name");
if (packageNameObj == null) {
throw runtime.newArgumentError("invalid package module");
}
String packageName = packageNameObj.asJavaString();
final String name = sym.trim().intern();
if (name.length() == 0) {
throw runtime.newArgumentError("empty class or package name");
}
String fullName = packageName + name;