--- a/src/core/object-factory.cc	Mon Mar 03 19:01:25 2008 +0100
+++ b/src/core/object-factory.cc	Mon Mar 03 19:33:28 2008 +0100
@@ -47,4 +47,16 @@
   return object;
 }
 
+std::ostream & operator << (std::ostream &os, const ObjectFactory &factory)
+{
+  return os;
+}
+std::istream & operator >> (std::istream &is, ObjectFactory &factory)
+{
+  return is;
+}
+
+
+VALUE_HELPER_CPP (ObjectFactory);
+
 } // namespace ns3