Modify SignalBase.value.

  If a signal contains a data deriving from Vector or Matrix, cast content into
  Matrix or Vector using plug machinery.

src/signal-base-py.cc

@@ -152,21 +152,57 @@ namespace dynamicgraph {
 	SignalBase<int>* signal = (SignalBase<int>*)pointer;
 
 	try {
-	  /* Temptative for specific signal type. */
-	  Signal<dynamicgraph::Vector,int> * sigvec
-	    = dynamic_cast< Signal<dynamicgraph::Vector,int>* >( signal );
-	  if( NULL!= sigvec )
-	    {
+	  { // --- VECTOR SIGNALS -----------------
+	    // Two cases: the signal embeds directly a vector, or embeds
+	    // an object deriving from vector.In the first case,
+	    // the signal is directly cast into sig<vector>.
+	    // In the second case, the derived object can be access as a vector
+	    // using the signal-ptr<vector> type.
+	    Signal<dynamicgraph::Vector,int> * sigvec
+	      = dynamic_cast< Signal<dynamicgraph::Vector,int>* >( signal );
+	    if( NULL!= sigvec ) {
 	      return vectorToPython( sigvec->accessCopy() );
 	    }
 
-	  Signal<dynamicgraph::Matrix,int> * sigmat
-	    = dynamic_cast< Signal<dynamicgraph::Matrix,int>* >( signal );
-	  if( NULL!= sigmat )
-	    {
+	    // Extraction of object derinving from vector: plug signal into
+	    // a vector signal and get the value from the signal-ptr instead
+	    // of the original vector.
+	    SignalPtr<dynamicgraph::Vector,int> sigptr(NULL,"vector-caster");
+	    try {
+	      sigptr.plug(signal);
+	      return vectorToPython( sigptr.accessCopy() );
+	    }
+	    catch( dynamicgraph::ExceptionSignal& ex ) {
+	      if( ex.getCode() !=
+		  dynamicgraph::ExceptionSignal::PLUG_IMPOSSIBLE )
+		throw;
+	    }
+	  }
+
+	  { // --- MATRIX SIGNALS --------------------
+	    // Two cases: the signal embeds directly a matrix, or embeds
+	    // an object deriving from matrix.In the first case,
+	    // the signal is directly cast into sig<matrix>.
+	    // In the second case, the derived object can be access as a matrix
+	    // using the signal-ptr<matrix> type.
+	    Signal<dynamicgraph::Matrix,int> * sigmat
+	      = dynamic_cast< Signal<dynamicgraph::Matrix,int>* >( signal );
+	    if( NULL!= sigmat ) {
 	      return matrixToPython( sigmat->accessCopy() );
 	    }
 
+	    SignalPtr<dynamicgraph::Matrix,int> sigptr(NULL,"matrix-caster");
+	    try {
+	      sigptr.plug(signal);
+	      return matrixToPython( sigptr.accessCopy() );
+	    }
+	    catch( dynamicgraph::ExceptionSignal& ex ) {
+	      if( ex.getCode() !=
+		  dynamicgraph::ExceptionSignal::PLUG_IMPOSSIBLE )
+		throw;
+	    }
+	  }
+
 	  Signal<double,int> * sigdouble
 	    = dynamic_cast< Signal<double,int>* >( signal );
 	  if( NULL!= sigdouble )