Visual Basic 6 supports some type of inheritance and polymorphism by implementing classes (or interfaces). These classes (or interfaces) declare and expose several members that have to be implemented in the classes that are applied from the interface.
Actually, the interface is a normal class with or without implementation that implicitly has an interface which is exposed to other classes.
The keyword Implements indicates that the class should implement all the exposed members contained in the class indicated right after the keyword.
…“Class 2 Implements Class 1”
The declared members in the implementing class should have a prefix with the name of the implemented class to indicate the implementing members. They must have the same signature (name, arguments and types) as the ones from the interface.
Upgrading Interfaces in Groups of Projects
The upgrading of multiple projects follows the same rules explained in all the others sections. The reason why this section is included is to mention that the VBUC provides support for interface upgrading to multiple projects. The only thing to be considered is the PreProcessing Phase, which gets and saves much information between projects in order to resolve all the important issue during upgrading. One of these issues is the interface upgrading, which uses the preprocessing info to generate the interfaces and implementing classes as expected.