User Guide

class 203
class
Availability
Flash Player 6.
Usage
[dynamic] class className [ extends superClass ]
[ implements interfaceName [, interfaceName... ] ]
{
// class definition here
}
Note: To use this keyword, you must specify ActionScript 2.0 and Flash Player 6 or later in the Flash
tab of your FLA file’s Publish Settings dialog box. This keyword is supported only when used in
external script files—not in scripts written in the Actions panel.
Parameters
className
The fully qualified name of the class.
superClass The name of the class that className extends (inherits from). This parameter is
optional.
interfaceName The name of the interface whose methods className must implement. This
parameter is optional.
Description
Statement; defines a custom class, which lets you instantiate objects that share methods and
properties that you define. For example, if you are developing an invoice-tracking system, you
could create an invoice class that defines all the methods and properties that each invoice should
have. You would then use the
new invoice() command to create invoice objects.
The name of the class must match the name of the external file that contains the class. The name
of the external file must be the name of the class with the file extension .as appended. For
example, if you name a class Student, the file that defines the class must be named Student.as.
If a class is within a package, the class declaration must use the fully qualified class name of the
form base.sub1.sub2.MyClass (for more information, see “Using packages” in Using ActionScript
in Flash). Also, the class’s AS file must be stored within the path in a directory structure that
reflects the package structure, such as base/sub1/sub2/MyClass.as (for more information, see
“Understanding the classpath” in Using ActionsScript in Flash). If a class definition is of the form
“class MyClass,” it is in the default package and the MyClass.as file should be in the top level of
some directory in the path.
For this reason, it’s good practice to plan your directory structure before you begin creating
classes. Otherwise, if you decide to move class files after you create them, you have to modify the
class declaration statements to reflect their new location.
You cannot nest class definitions; that is, you cannot define additional classes within a
class definition.
CHAPTER 2
ActionScript Language Reference