0.3 Inheritance - the big picture

Table of contents

• Preface
  • General
  • Viewing tip
    • Figures
    • Listings
  • Supplemental material
• General background information
  • Single and multiple inheritance
  • The ISA relationship
• Preview
• Discussion and sample code
  • The file named Skins01.mxml
  • The file named Driver.as
  • The file named FancyButton.as
• Run the program
• Resources
• Complete program listings
• Miscellaneous

Preface

General

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

The three main characteristics of an object-oriented program

Object-oriented programs exhibit three main characteristics:

• Encapsulation
• Inheritance
• Polymorphism

I explained encapsulation from a big-picture viewpoint in the previous lesson. (See Baldwin's ActionScript programming website .) In this lesson and the next, I will explain and illustrate inheritance and polymorphism from a big-picture viewpoint.Following that, I will get down in the weeds and start explaining in detail how to use ActionScript for object-oriented programming (OOP) .

Several ways to create and launch ActionScript programs

There are several ways to create and launch programs written in the ActionScript programming language. Most of the lessons in this series willuse Adobe Flex as the launch pad for the sample 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 study that lesson before embarking on the lessons in this series.

Some understanding of Flex MXML will be required

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

Will emphasize ActionScript code

It is often possible to use either ActionScript code or Flex MXML code to achieve the same result. 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 suitable alternative.

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 . Images used as skins for the buttons.
• Figure 2 . Program output at startup.
• Figure 3 . Mouse pointer hovering over the rightmost button.
• Figure 4 . Mouse pointer pressed on the rightmost button.
• Figure 5 . Mouse pointer hovering over the leftmost button.
• Figure 6 . Mouse pointer pressed on the leftmost button.
• Figure 7 . Skins01 project file structure.