All base classes should have a virtual destructor . If the class should be abstract (you want to prevent instantiating it) but it doesn’t happen to have any other pure virtual functions, a common technique to make the destructor pure virtual:
// file b.h
class B {
public: /*…other stuff…*/
virtual ~B() = 0; // pure virtual dtor
};
Of course, any derived class’ destructor must call the base class’ destructor, and so the destructor must still be defined (even if it’s empty):
// file b.cpp
B::~B() { /* possibly empty */ }
If this definition were not supplied, you could still derive classes from B but they could never be instantiated, which isn’t particularly useful.
June 11, 2010
C++