1. OLE servers and clients communicate with system libraries using virtual function tables, or VTBLs. 2. Some programming languages provide explicit language support for protocols or interfaces ( pure virtual functions . 3. The message-handling macros replaced the virtual function mechanism provided by C + +. 4. Virtual functions are resolved'late '.5. A class containing a pure virtual function is called an " abstract class ". 6. This mechanism avoided saturating the OO virtual function system with one function for each window message. 7. But instead, because it has a different signature, it creates a second virtual function . 8. The " fix " function accesses the function to be fixed as a virtual function . 9. Pure virtual functions can also be used where the method declarations are being used to define an Java programming language. 10. To elaborate on the above example, consider a base class with "'no virtual functions " '.
