The ObjectPtr implementation is a little tough to explain, and is based on the structural sub-typing mechanism I designed for my Interfaces proposal last year, and David Abraham's clever implementation which he posted on comp.std.c++. It essentially creates static function tables at compile-time, and stores a pointer to them along side the pointer to the value.

The code is posted at http://www.ootl.org/ootl/ootl_objects.hpp.htm, and some tests can be found at http://www.ootl.org/ootl/tests/ootl_test_objects.hpp.htm. I've tested the code using Visual C++ 7.1 and GCC 3.4. You can download the OOTL library ( which is now very compact because I have removed all references to Boost) at www.ootl.org

For those interested in the OOTL::ObjectPtr implementation, I recommend taking a look at the BIL Interfaces Library by Jonathan Turkanis. You can use his library to accomplish pretty much the same thing as follows:

BOOST_IDL_BEGIN(IObject)
BOOST_IDL_END(IObject)
typedef boost::manual_ptr ObjectPtr;