Visual Basic 2005 in a Nutshell, Third Edition

OOP Development in Visual Basic | 43

OOP

This is the Title of the Book, eMatter Edition

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

MyBase, MyClass, and Me

When working with derived classes, there are times when references to a member

may be somewhat ambiguous; a member name may exist in both the derived class

and the base class. Visual Basic provides special keywords to help alleviate this

ambiguity.

The

MyBase keyword provides a reference to the base class from within a derived

class. If you want to call a member of the base class from within a derived class,

you can use the syntax:

MyBase.MemberName

This will resolve any ambiguity if the derived class also has a member of the same

name. The

MyBase keyword can also be used to create an instance of the base class

through its constructor:

MyBase.New(...)

The MyBase keyword cannot be used to access Private members of the base class,

as they are inaccessible from derived classes.

If a class is derived from a chain of base and derived classes,

MyBase looks first to

the closet “parent” class in the chain for a matching member (including a

matching signature). If a match is not found, VB continues up the chain until the

root class, which is always System.Object.

The keywords

Me and MyClass both provide a reference to the local class (the class

in which the current code resides), but they exhibit slight differences. Consider a

class named ...