Flash CS3 Documentation

Learning ActionScript 2.0 in Adobe Flash > Classes > About working with custom classes in an application > About getter and setter methods

About getter and setter methods

Getter and setter methods are accessor methods, meaning that they are generally a public interface to change private class members. You use getter and setter methods to define a property. You access getter and setter methods as properties outside the class, even though you define them within the class as methods. Those properties outside the class can have a different name from the property name in the class.

There are some advantages to using getter and setter methods, such as the ability to let you create members with sophisticated functionality that you can access like properties. They also let you create read-only and write-only properties.

Even though getter and setter methods are useful, you should be careful not to overuse them because, among other issues, they can make code maintenance more difficult in certain situations. Also, they provide access to your class implementation, like public members. OOP practice discourages direct access to properties within a class.

When you write classes, you are always encouraged to make as many as possible of your instance variables private and add getter and setter methods accordingly. This is because there are several times when you may not want to let users change certain variables within your classes. For example, if you have a private static method that tracks the number of instances created for a specific class, you don't want a user to modify that counter using code. Only the constructor statement should increment that variable whenever it's called. In this situation, you might create a private instance variable and allow a getter method only for the counter variable, which means users are able to retrieve the current value only by using the getter method, and they won't be able to set new values using the setter method. Creating a getter without a setter is a simple way of making certain variables in your class read-only.

Flash CS3