Essential C# 2.0

Chapter 7. Interfaces Polymorphism is available not only via inheritance (as discussed in the previous chapter), but also via interfaces. Unlike abstract classes, interfaces cannot include any implementation. Like abstract classes, however, ...

Introducing Interfaces Beginner Topic: Why Interfaces? Implemented interfaces are like appliances with wall plugs. The wall plug is the interface that appliances support in order to receive AC power. An appliance can use that power in cou...

Polymorphism through Interfaces Consider another example (see Listing 7.2): IListable defines the members a class needs to support in order for the ConsoleListControl class to display it. As such, any class that implements IListable will have the ...

Interface Implementation Declaring a class to implement an interface is similar to deriving from a base class in that the implemented interfaces appear in a comma-separated list along with the base class (order is not significant). The only differ...

Casting between the Implementing Class and Its Interfaces Just as with a derived class and a base type, casting from an object to its implemented interface is an implicit cast. No cast operator is required because an instance of the implementing c...

Multiple Interface Inheritance Just as classes can implement multiple interfaces, interfaces can inherit from multiple interfaces, and the syntax is consistent with class derivation and implementation, as shown in Listing 7.9. Listing 7.9. Multip...

Implementing Multiple Inheritance via Interfaces As Listing 7.3 demonstrated, a single class can implement any number of interfaces in addition to deriving from a single class. This feature provides a possible enhancement to work around the lack o...

Versioning When creating a new version of a component or application that other developers have programmed against, you should not change interfaces. Because interfaces define a contract between the implementing class and the class using the inter...

Interfaces Compared with Classes Interfaces introduce another category of data types. (They are one of the few categories of types that don't extend System.Object.) Unlike classes, however, interfaces can never be instantiated. An interface instan...

Summary Interfaces are a critical extension of object-oriented programming. Their value was accentuated during the days of Component Object Model (COM) programming, when interfaces defined the API between components and were critical to the versio...