Dynamic methods are virtual methods with a slightly different dispatch mechanism. Because dynamic methods don't have entries in the object's virtual method table, they can reduce the amount of memory that objects consume. However, dispatching dynamic methods is somewhat slower than dispatching regular virtual methods. If a method is called frequently, or if its execution is time-critical, you should probably declare it as virtual rather than dynamic. 

Objects must store the addresses of their dynamic methods. But instead of receiving entries in the virtual method table, dynamic methods are listed separately. The dynamic method list contains entries only for methods introduced or overridden by a particular class. (The virtual method table, in contrast, includes all of the object's virtual methods, both inherited and introduced.) Inherited dynamic methods are dispatched by searching each ancestor's dynamic method list, working backwards through the inheritance tree. 

To make a method dynamic, add the directive dynamic after the method declaration.