HP Integrity NonStop J-Series - Manual (Page 284)

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©Copyright 1996 Rogue Wave Software
Redefinition of Virtual Functions
If you subclass off an existing class and override a virtual function, make sure that the overriding
function has exactly the same signature as the overridden function. This includes any const
modifiers!
This problem arises particularly when creating new RWCollectable classes. For example:
class MyObject : public RWCollectable {
public:
RWBoolean isEqual(); // No "const" !
};
The compiler will treat this definition of isEqual() as completely independent of the isEqual() in
the base class
RWCollectable, because it is missing a const modifier. Hence, if called through a
pointer:
MyObject obj;
RWCollectable* c = &obj;
c->isEqual(); // RWCollectable::isEqual() will get called!