21.7.2 Replicated Base Classes (cont.)

TeachingAssistant* can always be converted to an Employee*, then to a Person*
Without virtual inheritance, a TeachingAssistant* can not be converted directly to a Person*:
TeachingAssistant* fred = new TeachingAssistant(); Student* s = fred; // Legal, because TeachingAssistant is-a Student Person* p1 = s; Employee* e = fred; Person* p2 = e; Person* p3 = fred; // Legal if virtual inheritance used, otherwise error