Chapter 3: About Actionscript - MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH Manual

CHAPTER 3
About ActionScript
The object-oriented programming (OOP) features in ActionScript 2.0 are based on the
ECMAScript 4 Draft Proposal currently in development by ECMA TC39-TG1 (see
www.mozilla.org/js/language/es4/index.html). Because the ECMA-4 proposal is not yet a
standard, and because it is still changing, ActionScript 2.0 is loosely based on this
specification.
ActionScript 2.0 supports all the standard elements of the ActionScript language; it lets you
write scripts that more closely adhere to standards used in other object-oriented languages,
such as Java. ActionScript 2.0 should be of interest primarily to intermediate or advanced
Flash developers who are building applications that require the implementation of classes and
subclasses. ActionScript 2.0 also lets you declare the object type of a variable when you create
it (see "About assigning data types and strict data typing" on page
significantly improved compiler errors (see
Key facts about ActionScript 2.0 include the following points:
Scripts that use ActionScript 2.0 to define classes or interfaces must be stored as external
script files, with a single class defined in each script; that is, classes and interfaces cannot
be defined in the Actions panel.
You can import individual class files implicitly (by storing them in a location specified by
global or document-specific search paths and then using them in a script) or explicitly (by
using the command); you can import packages (collections of class files in a
import
directory) by using wildcards.
Applications developed with ActionScript 2.0 are supported by Flash Player 6 and later.
The default publish setting for new files created in Flash 8 is ActionScript 2.0. If you
plan to modify an existing FLA file with ActionScript 1.0 to use ActionScript 2.0
syntax, ensure that the FLA file specifies ActionScript 2.0 in its publish settings. If it
does not, your file will compile incorrectly, although Flash will not necessarily
generate compiler errors.
For more information on using ActionScript 2.0 to write object-oriented programs in Flash,
see Chapter 7, "Classes," on page
Appendix A, "Error Messages," on page
225.
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