Improve cpp11_function_objects test for python

Examples/test-suite/cpp11_function_objects.i

@@ -3,25 +3,31 @@
    Function objects are objects which overload the operator() function.
    The std::function does not provide any seamless support in the target languages yet.
 */
-%module cpp11_function_objects
+%module(directors="1") cpp11_function_objects
 
 %rename(__call__) Test::operator();
 
+%feature("director") Test;
+
 %inline %{
-struct Test {
+class Test {
+public:
   int value;
   
-  void operator()(int x, int y) {
+  virtual void operator()(int x, int y) {
     value=x+y;
   }
   Test() : value(0) {}
-} test;
+  ~Test() {}
+};
+
+Test test;
 
 #include <functional>
 std::function<void ( int, int )> pF = test;
 
-int testit1(Test new_test, int a, int b) {
-  pF = new_test;
+int testit1(Test &new_test, int a, int b) {
+  pF = std::ref(new_test);
   pF(a, b);
   return new_test.value;
 }