Deleting downcast not invoking destructor - any idea?

OK, here is the prob.

I create a class, A, and B as a derived class thereof.

When I use

A* classAPointerThatIsActuallyB = new B;

then the constructors for A and B are called.

When I call a virtual from A that B overrides, the B function is called. Basic polymorphism there.

But, when I

delete classAPointerThatIsActuallyB;

Only the destructor for A is called. Any ideas on how would I go about making sure that anything done by B::B() is properly undone by B::~B(), without modifying class A?

declare ~A and ~B as virtual function.

Remember : if any derive is needed, declare the destructor as virtual function.

Is there any way to do this without changing A? if my pointer knows that it is a B, is there any way to tell that to delete?

hmm...

then, RTTI can help you. But it is slow and complex.
Example:

Code:

---

if(typeid(B) == typeid(*p))
    delete dynamic_cast<B*>p;
else
    delete p;

---

Compile this code with VC6, you must use /g option, or you'll receive an warn and your program will run to crash.