Chapter Summary

C++ is used to solve a wide range of problems—from those solvable in a few hours’ time to those that take years of development by large teams. Some features in C++ are most applicable in the context of large-scale problems: exception handling, namespaces, and multiple or virtual inheritance.

Exception handling lets us separate the error-detection part of the program from the error-handling part. When an exception is thrown, the current executing function is suspended and a search is started to find the nearest matching catch clause. Local variables defined inside functions that are exited while searching for a catch clause are destroyed as part of handling the exception.

Namespaces are a mechanism for managing large, complicated applications built from code produced by independent suppliers. A namespace is a scope in which objects, types, functions, templates, and other namespaces may be defined. The standard library is defined inside the namespace named std.

Conceptually, multiple inheritance is a simple notion: A derived class may inherit from more than one direct base class. The derived object consists of the derived part and a base part contributed by each of its base classes. Although conceptually simple, the details can be more complicated. In particular, inheriting from multiple base classes introduces new possibilities for name collisions and resulting ambiguous references to names from the base part of an object.

When a class inherits directly from more than one base class, it is possible that those classes may themselves share another base class. In such cases, the intermediate classes can opt to make their inheritance virtual, which states a willingness to share their virtual base class with other classes in the hierarchy that inherit virtually from that same base class. In this way there is only one copy of the shared virtual base in a subsequently derived class.