Actionscript Cookbook

12.2. Creating an Instance of a Class

Problem

You want to access the properties and methods of a class to achieve a particular goal, but those properties and methods are specific to a particular object (i.e., an instance of the class).

Solution

Create a instance of the class using the new operator and the constructor function for the class of interest. Then access the properties and methods of the instance, as returned by the constructor function.

Discussion

Many ActionScript classes must be instantiated before you can use them. This means that you must create an object that is based on the blueprint defined by the class. For example, the Array class defines the blueprint for all arrays. All arrays have the same kinds of properties and methods; however, each array instance is an individual object that merely inherits the common properties and methods from the class. It is important that each instance be individualized so that when you request the value for arrayA.length, you retrieve the length of arrayA and not the length of some other array, such as arrayB.

To create an instance of a class, you typically use the new operator with the appropriate constructor function for the class. The constructor function takes the same name as the class itself and is followed by the function operator (that is, parentheses). For example, the following creates a new generic instance of the Object class:

myObject = new Object(  );

Note that the new statement returns an instance of the class, which ...