Unique class type Id that is safe and holds across library boundaries

I would appreciate any help as C++ is not my primary language.

I have a template class that is derived in multiple libraries. I am trying to figure out a way to uniquely assign an id int to each derived class. I need to be able to do it from a static method though, ie.

template < class DERIVED >
class Foo
{
public:
    static int s_id()
    {
        // return id unique for DERIVED
    }
    // ...
};