Question

I think virtual alone is generally sufficient.

Is there another reason to make it pure virtual than to force derived classes to implement their own destructor? I mean if you allocate something in your class’ constructor you should impement your own destructor – if your class is derived or not.

Doesn’t count as answer as I already know: If you want your class abstract and it has no pure virtual functions – leave it to the destructor.

Some more uses?

Answer 1

If you want your class abstract and it
has no pure virtual functions – leave
it to the destructor.

Actually, I don’t think there’s more. All the pure virtual destructor does, is make the whole class abstract. You have to provide the implementation for the pure virtual destructor as well as for a non-pure virtual destructor, the destructors of the derived classes are virtual with virtual destructor alone, etc.

Basically, if a class has already some pure virtual functions, its behaviour would be equivalent with virtual and pure-virtual destructor.