code: public static void addObjectExtractor (Digester dig, String type, String base,
          String methodName)
      {
          String prefix = base + "/" + type + "/object";
          dig.addObjectCreate(prefix, ObjectInfo.class);
          dig.addRule(prefix, new SetPropertyFieldsRule());
          dig.addSetNext(prefix, methodName, ObjectInfo.class.getName());
      }
docs: Adds a set of rules to <code>dig</code> to create an Object info from the element at
  base/type/object and calls <code>methodName</code> on the object on dig's stack.