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

Question

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 uniq

Answer 1

What kind of ID? Are you looking for an atomically increasing int? If a string is fine, what about:

static string s_id()
{
   return typeid(Foo).name();
}

If it needs to be an int, but not automatically increasing, you could hash that for a 128-bit integer unlikely to have collisions (though likely a larger number than you need)