Visual Basic 2005 in a Nutshell, Third Edition

Changes in Object Orientation | 701

What’s New

2002

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

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, events, and other types of the base class. Since .NET

forms are classes, inheritance applies to them as well. This allows new forms to be

created based on existing control-laden forms.

Overloading

VB.NET supports a language feature known as function overloading. Within a

class, a single method can include multiple argument signature variations. That is,

the number and data type of each method argument can vary between the

different versions, despite the method having the same name in each version. The

following declarations are valid in the same class.

Public Overloads Sub OpenFile( )

' ----- Prompt user for file to open, and open it.

End Sub

Public Overloads Sub OpenFile(ByVal fileToOpen As String)

' ----- Open the specified file.

End Sub

Object Creation

VB 6 supports a form of object creation called implicit object creation. If an object

variable is declared using the

New keyword, as in:

Dim obj As New SomeClass

then the object is created the first time it is used in code. More specifically, the

object variable is initially given the value

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