0.1 What is oop and why should i care?

Table of contents

• Preface
  • General
  • Viewing tip
    • Figures
    • Listings
  • Supplemental material
• What is object-oriented programming (OOP)?
• Why should I care?
• General background information
• A slightly more technical description of OOP
  • Encapsulation example
  • Inheritance example
  • Polymorphism example
• Object-oriented programming vocabulary
• Sample code
  • A simple class named MyClass
  • A custom component - NumericTextAreaA
• Resources
• Miscellaneous

Preface

General

This tutorial lesson is part of a continuing series of lessons dedicated to object-oriented programming (OOP) with ActionScript.

There are several ways to create and launch programs written in the ActionScript programming language. Many of the lessons in this series willuse Adobe Flex as the launch pad for ActionScript programs. An earlier lesson titled The Default Application Container provided information on how to get started programming with Adobe's Flex Builder 3. (See Baldwin's Flex programming website .) You should read that lesson before embarking on the lessons in this series.

One of the complicating factors

One of the complicating factors in using Adobe Flex as the launch pad for ActionScript programs is the difficulty of understanding the relationships thatexist between Flex and ActionScript. I recommend that you study the following lessons on Baldwin's Flex programming website that address that topic:

• 114 Integrating ActionScript and Flex
• 116 Defining Custom MXML Components
• 118 Defining Custom ActionScript Components
• 120 Creating Online Tests using Custom ActionScript Components

I recommend that you also study all of the other lessons on Baldwin's Flex programming website in parallel with your study of these ActionScript lessons. Eventually youwill probably need to understand both technologies and the relationships that exist between them in order to become a successful ActionScript programmer.

Another complicating factor

Another complicating factor is knowing whether to use ActionScript code or Flex MXML code to achieve a particular objective. In many cases, eitherwill do the job.

Insofar as this series of lessons is concerned, the emphasis will be on ActionScript code even in those cases where Flex MXML code may be a suitablealternative.

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the figures andlistings while you are reading about them.

Figures

• Figure 1 . Guideline for OOP.
• Figure 2 . Two objects of the class named MyClass.
• Figure 3 . An object ofthe class named NumericTextAreaA.

Listings

• Listing 1 . Class file named MyClass.as.
• Listing 2 . Flex file named SimpleClass01.mxml.
• Listing 3 . The filenamed NumericTextArea01.mxml.
• Listing 4 . The classdefinition for NumericTextAreaA.