without memory management and object ownership
I think a useful complement to the pointer types in boost.smart_ptr would be something I've referred to as passive_ptr<>. It's passive in the sense that it doesn't imply object ownership and therefore doesn't involve itself in object lifetime management. The problem I am interested in solving is the case where you see bare pointers (i.e. non-smart pointers) being used in code and you're not sure whether there's a good reason that they're not one of the smart pointers (or auto_ptr<>, which I normally use in cases where I really want scoped_ptr<>, but I need to transfer ownership out of it). Also, it's helpful to easily know that it's not a bug that the pointer isn't deleted. In other words, a passive_ptr<> class wouldn't add any functionality over a bare pointer, but it would enable users to communicate semantic intent. Perhaps that covers some of what you're targeting with valid_ptr<>? As for ensuring validity, I don't see how this is possible without getting involved in lifetime management. Matt