Provides a handy way to cast a pointer to a pointer to a class object while checking to see if the cast is legal.
DYNAMIC_DOWNCAST(class, pointer )
- The name of a class.
- A pointer to be cast to a pointer to an object of type class.
The macro will cast the pointer parameter to a pointer to an object of the class parameter's type.
If the object referenced by the pointer is a "kind of" the identified class, the macro returns the appropriate pointer. If it is not a legal cast, the macro returns NULL.