Visual Basic 2005 in a Nutshell, Third Edition

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Chapter 3: Introduction to Object-Oriented Programming

This is the Title of the Book, eMatter Edition

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

Dog-specific versions of those members can be added to the Dog class. Any Dog

object that calls these methods will use the Dog-specific versions; any general Pet

object will use the default Pet-specific versions. If your code is currently treating a

Dog object as a more generic Pet object, it will still use the Dog-specific versions,

since the object is still a Dog.

Sound confusing? Welcome to polymorphism. Fortunately, the Visual Basic

compiler figures out all of these relationships for you; you just need to write your

code to enable the class-specific actions you require.

Overloading

Sometimes it is useful to have more than one way of performing the same action

in a single class. For instance, if your Dog class has a TakeForWalk action, you

might require several ways of taking this action to mimic real-world actions. For

instance, you might want to call TakeForWalk with a time duration (“30

minutes”) for a generic time-based walk, or call it with instructions for a specific

path-based exercise plan. You would need one version of this action that takes a

number (time-based) and one that takes a path plan (path-based), perhaps sent as

a string.

When a class includes multiple versions of the same member that differ by their

argument ...