Enable automatic downcasting to registered classes for pointers, references, and smart pointers

[SVN r16673]

test/polymorphism.cpp

@@ -3,7 +3,14 @@
 // copyright notice appears in all copies. This software is provided
 // "as is" without express or implied warranty, and with no claim as
 // to its suitability for any purpose.
-#include <boost/python.hpp>
+#include <boost/python/module.hpp>
+#include <boost/python/class.hpp>
+#include <boost/python/return_value_policy.hpp>
+#include <boost/python/manage_new_object.hpp>
+#include <boost/python/reference_existing_object.hpp>
+#include <boost/python/call_method.hpp>
+#include <boost/python/def.hpp>
+#include <boost/utility.hpp>
 
 using namespace boost::python;
 
@@ -40,6 +47,11 @@ struct B : A
     virtual std::string f() { return "B::f()"; }
 };
 
+struct C : A
+{
+    virtual std::string f() { return "C::f()"; }
+};
+
 A& getBCppObj ()
 {
     static B b;
@@ -48,6 +60,25 @@ A& getBCppObj ()
 
 std::string call_f(A& a) { return a.f(); }
 
+A* factory(unsigned choice)
+{
+    switch (choice % 3)
+    {
+    case 0: return new A;
+        break;
+    case 1: return new B;
+        break;
+    default: return new C;
+        break;
+    }
+}
+
+C& getCCppObj ()
+{
+    static C c;
+    return c;
+}
+
 BOOST_PYTHON_MODULE_INIT(polymorphism_ext)
 {
     class_<A,boost::noncopyable,ACallback>("A")
@@ -56,6 +87,14 @@ BOOST_PYTHON_MODULE_INIT(polymorphism_ext)
     
     def("getBCppObj", getBCppObj, return_value_policy<reference_existing_object>());
 
+    class_<C,bases<A>,boost::noncopyable>("C")
+        .def("f", &C::f)
+        ;
+    
+    def("getCCppObj", getCCppObj, return_value_policy<reference_existing_object>());
+
+    def("factory", factory, return_value_policy<manage_new_object>());
+
     def("call_f", call_f);
 }