--- a/src/core/composite-trace-resolver.cc	Tue Aug 28 14:33:53 2007 +0200
+++ b/src/core/composite-trace-resolver.cc	Tue Aug 28 14:51:13 2007 +0200
@@ -374,7 +374,7 @@
 CompositeTraceResolverTest::TraceDouble (TraceContext const &context, double v)
 {
   TraceSourceTest source;
-  context.Get (source);
+  context.GetElement (source);
   if (source.IsDoubleA ())
     {
       m_gotDoubleA = true;

--- a/src/core/trace-context.cc	Tue Aug 28 14:33:53 2007 +0200
+++ b/src/core/trace-context.cc	Tue Aug 28 14:51:13 2007 +0200
@@ -358,25 +358,25 @@
     {
       ok = false;
     }
-  ctx.Get (v0);
+  ctx.GetElement (v0);
   ctx.AddElement (v1);
-  ctx.Get (v1);
-  ctx.Get (v0);
-  ctx.Get (v1);
+  ctx.GetElement (v1);
+  ctx.GetElement (v0);
+  ctx.GetElement (v1);
 
   TraceContext copy = ctx;
-  ctx.Get (v0);
-  ctx.Get (v1);
-  copy.Get (v0);
-  copy.Get (v1);
+  ctx.GetElement (v0);
+  ctx.GetElement (v1);
+  copy.GetElement (v0);
+  copy.GetElement (v1);
   copy.AddElement (v2);
-  copy.Get (v0);
-  copy.Get (v1);
-  copy.Get (v2);
+  copy.GetElement (v0);
+  copy.GetElement (v1);
+  copy.GetElement (v2);
   ctx.AddElement (v3);
-  ctx.Get (v0);
-  ctx.Get (v1);
-  ctx.Get (v3);
+  ctx.GetElement (v0);
+  ctx.GetElement (v1);
+  ctx.GetElement (v3);
 
   if (ctx.SafeGet (v2))
     {
@@ -387,13 +387,13 @@
       ok = false;
     }
   ctx.Union (copy);
-  ctx.Get (v2);
+  ctx.GetElement (v2);
   if (copy.SafeGet (v3))
     {
       ok = false;
     }
   copy.Union (ctx);
-  copy.Get (v3);  
+  copy.GetElement (v3);  
   
   return ok;
 }

--- a/src/core/trace-context.h	Tue Aug 28 14:33:53 2007 +0200
+++ b/src/core/trace-context.h	Tue Aug 28 14:51:13 2007 +0200
@@ -34,8 +34,10 @@
  *
  * Instances of this class are used to hold context
  * for each trace source. Each instance holds a list of
- * 'contexts'. Trace sinks can lookup these contexts
+ * TraceContextElement. Trace sinks can lookup these contexts
  * from this list with the ns3::TraceContext::Get method.
+ * They can also ask the TraceContext for the list of 
+ * TraceContextElements it contains with the PrintAvailable method.
  *
  * This class is implemented
  * using Copy On Write which means that copying unmodified
@@ -54,6 +56,9 @@
 
   /**
    * \param context add context to list of trace contexts.
+   *
+   * A copy of the input context is appended at the end of the list
+   * stored in this TraceContext.
    */
   template <typename T>
   void AddElement (T const &context);
@@ -63,7 +68,7 @@
    *
    * Perform the Union operation (in the sense of set theory) on the
    * two input lists of elements. This method is used in the
-   * ns3::CallbackTraceSourceSource class when multiple sinks are connected
+   * ns3::CallbackTraceSource class when multiple sinks are connected
    * to a single source to ensure that the source does not need
    * to store a single TraceContext instance per connected sink.
    * Instead, all sinks share the same TraceContext.
@@ -72,15 +77,35 @@
 
   /**
    * \param context context to get from this list of trace contexts.
-   *
-   * This method cannot fail. If the requested trace context is not
-   * stored in this TraceContext, then, the program will halt.
+   * \returns true if the requested trace context element was found 
+   *          in this TraceContext, false otherwise.
    */
   template <typename T>
-  void Get (T &context) const;
+  bool GetElement (T &context) const;
 
+  /**
+   * \param os a c++ STL output stream
+   *
+   * Iterate over the list of TraceContextElement stored in this
+   * TraceContext and invoke each of their Print method.
+   */
   void Print (std::ostream &os) const;
+  /**
+   * \param os a c++ STL output stream
+   * \param separator the separator inserted between each TraceContextElement typename.
+   *
+   * Print the typename of each TraceContextElement stored in this TraceContext.
+   */
   void PrintAvailable (std::ostream &os, std::string separator) const;
+  /**
+   * \param o another trace context
+   * \returns true if the input trace context contains exactly the same set of
+   *          TraceContextElement instances, false otherwise.
+   *
+   * This method does not test for equality: the content of each matching 
+   * TraceContextElement could be different. It merely checks that both
+   * trace contexts contain the same types of TraceContextElements.
+   */
   bool IsSimilar (const TraceContext &o) const;
 private:
   friend class TraceContextTest;
@@ -123,8 +148,8 @@
     }
 }
 template <typename T>
-void
-TraceContext::Get (T &context) const
+bool
+TraceContext::GetElement (T &context) const
 {
   TraceContextElement *parent;
   // if the following assignment fails, it is because the input
@@ -132,10 +157,7 @@
   parent = &context;
   uint8_t *data = (uint8_t *) &context;
   bool found = DoGet (T::GetUid (), data);
-  if (!found)
-    {
-      NS_FATAL_ERROR ("Type not stored in TraceContext");
-    }
+  return found;
 }
 template <typename T>
 bool

--- a/src/core/trace-resolver.h	Tue Aug 28 14:33:53 2007 +0200
+++ b/src/core/trace-resolver.h	Tue Aug 28 14:51:13 2007 +0200
@@ -35,10 +35,9 @@
  *        namespace resolution.
  * \ingroup tracing
  *
- * Subclasses must implement the two pure virtal methods defined in 
- * this base class:
- *  - ns3::TraceResolver::Connect
- *  - ns3::TraceResolver::Disconnect.
+ * Although users could conceivably implement their own trace resolver
+ * subclasses, doing so is complicated so, it is recommended to use
+ * the default implementation ns3::CompositeTraceResolver instead.
  */
 class TraceResolver
 {
@@ -88,6 +87,14 @@
     typedef std::vector<struct Source> SourceVector;
     SourceVector m_sources;
   };
+  /**
+   * \param path the path to the current recursive level.
+   * \param context the trace context associated to the current recursive level
+   * \param collection the collection in which to gather every trace source found.
+   *
+   * This method is invoked recursively until all trace sources have been
+   * stored in the output SourceCollection argument.
+   */
   virtual void CollectSources (std::string path, const TraceContext &context, 
                                SourceCollection *collection) = 0;
 protected:

--- a/src/internet-node/pcap-trace.cc	Tue Aug 28 14:33:53 2007 +0200
+++ b/src/internet-node/pcap-trace.cc	Tue Aug 28 14:51:13 2007 +0200
@@ -83,7 +83,7 @@
 PcapTrace::LogIp (TraceContext const &context, Packet const &p, uint32_t interfaceIndex)
 {
   NodeListIndex nodeIndex;
-  context.Get (nodeIndex);
+  context.GetElement (nodeIndex);
   PcapWriter *writer = GetStream (nodeIndex.Get (), interfaceIndex);
   writer->WritePacket (p);
 }