Professional Visual Basic® 2008

Chapter 3. Object-Oriented Programming

Visual Basic is a fully object-oriented language. Chapter 2 covered the basics of creating classes and objects, including the creation of methods, properties, events, operators, and instance variables. You have seen the basic building blocks for abstraction, encapsulation, and polymorphism — concepts discussed in more detail at the end of this chapter. The final major techniques you need to understand are inheritance and the use of multiple interfaces.

Inheritance is the idea that you can create a class that reuses methods, properties, events, and variables from another class. You can create a class with some basic functionality, and then use that class as a base from which to create other, more detailed, classes. All these derived classes will have the same common functionality as that base class, along with new, enhanced, or even completely changed functionality.

This chapter covers the syntax that supports inheritance within Visual Basic. This includes creating the base classes from which other classes can be derived, as well as creating those derived classes.

Visual Basic also supports a related concept: multiple interfaces. As shown in Chapter 2, all objects have a native or default interface, which is defined by the public methods, properties, and events declared in the class. In the .NET environment, an object can have other interfaces in addition to this native interface — in other words, .NET objects can have multiple interfaces.

These ...