diff -r 2324032b8f90 examples/wifi-ap.cc
--- a/examples/wifi-ap.cc	Thu Mar 20 10:25:59 2008 -0700
+++ b/examples/wifi-ap.cc	Thu Mar 20 18:50:47 2008 +0000
@@ -47,32 +47,32 @@ using namespace ns3;
 using namespace ns3;
 
 void
-DevTxTrace (std::string context, Ptr<const Packet> p, Mac48Address address)
+DevTxTrace (Config::Path context, Ptr<const Packet> p, Mac48Address address)
 {
   std::cout << " TX to=" << address << " p: " << *p << std::endl;
 }
 void
-DevRxTrace (std::string context, Ptr<const Packet> p, Mac48Address address)
+DevRxTrace (Config::Path context, Ptr<const Packet> p, Mac48Address address)
 {
   std::cout << " RX from=" << address << " p: " << *p << std::endl;
 }
 void
-PhyRxOkTrace (std::string context, Ptr<const Packet> packet, double snr, WifiMode mode, enum WifiPreamble preamble)
+PhyRxOkTrace (Config::Path context, Ptr<const Packet> packet, double snr, WifiMode mode, enum WifiPreamble preamble)
 {
   std::cout << "PHYRXOK mode=" << mode << " snr=" << snr << " " << *packet << std::endl;
 }
 void
-PhyRxErrorTrace (std::string context, Ptr<const Packet> packet, double snr)
+PhyRxErrorTrace (Config::Path context, Ptr<const Packet> packet, double snr)
 {
   std::cout << "PHYRXERROR snr=" << snr << " " << *packet << std::endl;
 }
 void
-PhyTxTrace (std::string context, Ptr<const Packet> packet, WifiMode mode, WifiPreamble preamble, uint8_t txPower)
+PhyTxTrace (Config::Path context, Ptr<const Packet> packet, WifiMode mode, WifiPreamble preamble, uint8_t txPower)
 {
   std::cout << "PHYTX mode=" << mode << " " << *packet << std::endl;
 }
 void
-PhyStateTrace (std::string context, Time start, Time duration, enum WifiPhy::State state)
+PhyStateTrace (Config::Path context, Time start, Time duration, enum WifiPhy::State state)
 {
   std::cout << " state=";
   switch (state) {
diff -r 2324032b8f90 src/core/config.cc
--- a/src/core/config.cc	Thu Mar 20 10:25:59 2008 -0700
+++ b/src/core/config.cc	Thu Mar 20 18:50:47 2008 +0000
@@ -469,6 +469,44 @@ void UnregisterRootNamespaceObject (Ptr<
   Singleton<ConfigImpl>::Get ()->UnregisterRootNamespaceObject (obj);
 }
 
+std::string Path::GetComponentString (uint32_t componentIndex) const
+{
+  NS_ASSERT (m_path [0] == '/');
+  std::string::size_type componentStart = 1;
+  uint32_t currentComponent = 0;
+  for (std::string::size_type pos = 1;; pos++)
+    {
+      char c = m_path [pos];
+      if (c == '/')
+        {
+          if (currentComponent == componentIndex)
+            {
+              return m_path.substr (componentStart, pos - componentStart);
+            }
+          pos++;
+          componentStart = pos;
+          currentComponent++;
+        }
+      else if (c == '\0')
+        {
+          if (currentComponent == componentIndex)
+            {
+              return m_path.substr (componentStart, pos - componentStart);
+            }
+        }
+    }
+  return std::string ();
+}
+
+uint32_t Path::GetComponentUint32 (uint32_t componentIndex) const
+{
+  std::istringstream iss;
+  iss.str (GetComponentString (componentIndex));
+  uint32_t result;
+  iss >> result;
+  return result;
+}
+
 } // namespace Config
 
 } // namespace ns3
diff -r 2324032b8f90 src/core/config.h
--- a/src/core/config.h	Thu Mar 20 10:25:59 2008 -0700
+++ b/src/core/config.h	Thu Mar 20 18:50:47 2008 +0000
@@ -118,6 +118,31 @@ void RegisterRootNamespaceObject (Ptr<Ob
  */
 void UnregisterRootNamespaceObject (Ptr<Object> obj);
 
+
+class Path
+{
+public:
+  Path (std::string path) : m_path (path) {}
+  std::string GetComponentString (uint32_t componentIndex) const;
+  uint32_t GetComponentUint32 (uint32_t componentIndex) const;
+
+  friend inline bool operator != (const Path &pathA, const Path &pathB);
+  friend inline bool operator < (const Path &pathA, const Path &pathB);
+
+private:
+  std::string m_path;
+};
+
+inline bool operator != (const Path &pathA, const Path &pathB)
+{
+  return pathA.m_path != pathB.m_path;
+}
+
+inline bool operator < (const Path &pathA, const Path &pathB)
+{
+  return pathA.m_path < pathB.m_path;
+}
+
 } // namespace Config
 
 } // namespace ns3
diff -r 2324032b8f90 src/core/traced-callback.h
--- a/src/core/traced-callback.h	Thu Mar 20 10:25:59 2008 -0700
+++ b/src/core/traced-callback.h	Thu Mar 20 18:50:47 2008 +0000
@@ -24,6 +24,7 @@
 
 #include <list>
 #include "callback.h"
+#include "config.h"
 
 namespace ns3 {
 
@@ -80,9 +81,9 @@ void
 void 
 TracedCallback<T1,T2,T3,T4>::Connect (const CallbackBase & callback, std::string path)
 {
-  Callback<void,std::string,T1,T2,T3,T4> cb;
+  Callback<void,Config::Path,T1,T2,T3,T4> cb;
   cb.Assign (callback);
-  Callback<void,T1,T2,T3,T4> realCb = cb.Bind (path);
+  Callback<void,T1,T2,T3,T4> realCb = cb.Bind (Config::Path (path));
   m_callbackList.push_back (realCb);
 }
 template<typename T1, typename T2, 
@@ -108,9 +109,9 @@ void
 void 
 TracedCallback<T1,T2,T3,T4>::Disconnect (const CallbackBase & callback, std::string path)
 {
-  Callback<void,std::string,T1,T2,T3,T4> cb;
+  Callback<void,Config::Path,T1,T2,T3,T4> cb;
   cb.Assign (callback);
-  Callback<void,T1,T2,T3,T4> realCb = cb.Bind (path);
+  Callback<void,T1,T2,T3,T4> realCb = cb.Bind (Config::Path (path));
   DisconnectWithoutContext (realCb);
 }
 template<typename T1, typename T2,