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Object-oriented Programming
Designing Objects: Inheritance, Polymorphism, and Delegation : Interface hierarchies and inheritance

Interface hierarchies and inheritance

You can define an interface by inheriting the member prototypes from other interfaces as well as by defining member prototypes directly. Any class instance that implements the interface must implement the members of all super interfaces in the interface hierarchy as well as its own members. In addition, the class instance can be referenced as any of the super interface types as well as the interface type that inherits them. This provides an additional dimension to enable access to any object that implements the interface. The following sections detail how an interface hierarchy can be built, including limitations and guidelines for using it.
* Multiple interfaces in a hierarchy
* Duplicate members in a hierarchy
* Using interface hierarchies