Exceptions and Inheritance
Various exception classes can be derived from a common base class, as we discussed in Section 16.3, when we created class DivideByZeroException as a derived class of class exception. If a catch handler catches a pointer or reference to an exception object of a base-class type, it also can catch a pointer or reference to all objects of classes publicly derived from that base classthis allows for polymorphic processing of related errors.
Error-Prevention Tip 16.5
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Using inheritance with exceptions enables an exception handler to catch related errors with concise notation. One approach is to catch each type of pointer or reference to a derived-class exception object individually, but a more concise approach is to catch pointers or references to base-class exception objects instead. Also, catching pointers or references to derived-class exception objects individually is error prone, especially if the programmer forgets to test explicitly for one or more of the derived-class pointer or reference types. |