[C++-sig] type traits

[Piotr Jaroszyński]

Hello,

I thought (and saw) that boost.python is using type traits to figure out the 
real type of polymorphic pointers/references and hence I am really surprised 
that with the following code it doesn't happen:

#include <boost/python.hpp>

namespace bp = boost::python;
 
struct Base
{
};
 
struct Derived :
    Base
{
};
 
const boost::shared_ptr<Base>
get_derived()
{
    static boost::shared_ptr<Base> foo(boost::shared_ptr<Derived>(new 
Derived()));
    return foo;
}
 
BOOST_PYTHON_MODULE(type_magic)
{
    bp::class_<Base>("Base", bp::no_init);
    bp::register_ptr_to_python<boost::shared_ptr<Base> >();
    bp::class_<Derived, bp::bases<Base> >("Derived", bp::no_init);
    bp::def("get_derived", &get_derived);
}

in python get_derived gives me:
<type_magic.Base object at 0x2adb9e8ba848>

For the "saw" part, I have working code, which does exactly what I expected 
(getting a Derived object in python) and I can't really find a difference 
between it and this basic testcase, but I am probably just missing something. 
Any clues what that could be?

-- 
Best Regards,
Piotr Jaroszyński