VB.NET Language in a Nutshell, Second Edition

Changes in Object-Orientation

As you may know, Visual Basic has implemented some features of object-oriented programming since Version 4. However, in terms of object-orientation, the step from Version 6 to VB.NET is very significant. Indeed, some people did not consider VB 6 (or earlier versions) to be a truly object-oriented programming language. Whatever your thoughts may have been on this matter, it seems clear that VB.NET is an object-oriented programming language by any reasonable definition of that term.

Here are the main changes in the direction of object-orientation. We discuss these issues in detail in Chapter 4.

Inheritance

VB.NET supports object-oriented inheritance (but not multiple inheritance). This means that a class can derive from another (base) class, thereby inheriting all of the properties, methods, and events of the base class. Since forms are also classes, inheritance applies to forms as well. This allows new forms to be created based on existing forms. We discuss inheritance in detail in Chapter 4.

Overloading

VB.NET supports a language feature known as function overloading. The idea is simple and yet quite useful. We can use the same name for different functions (or subroutines), as long as the functions can be distinguished by their argument signature. The argument signature of a function (or subroutine) is the sequence of data types of the arguments of the function. Thus, in order for two functions to have the same argument signature, they must have the ...