User Guide

Classes 109
public class BitmapData {}
}
Class attributes
ActionScript 3.0 allows you to modify class definitions using one of the following four
attributes:
For each of these attributes, except for
internal, you must explicitly include the attribute to
get the associated behavior. For example, if you do not include the
dynamic attribute when
defining a class, you will not be able to add properties to a class instance at run time. You
explicitly assign an attribute by placing it at the beginning of the class definition, as the
following code demonstrates:
dynamic class Shape {}
Notice that the list does not include an attribute named abstract. This is because abstract
classes are not supported in ActionScript 3.0. Notice also that the list does not include
attributes named
private and protected. These attributes have meaning only inside a class
definition, and cannot be applied to classes themselves. If you do not want a class to be
publicly visible outside a package, place the class inside a package and mark the class with the
internal attribute. Alternatively, you can omit both the internal and public attributes,
and the compiler will automatically add the
internal attribute for you. If you do not want a
class to be visible outside the source file in which it is defined, place the class at the bottom of
your source file below the closing curly brace of the package definition.
Attribute Definition
dynamic
Allow properties to be added to instances at run time.
final
Must not be extended by another class.
internal (default) Visible to references inside the current package.
public
Visible to references everywhere.