MACROMEDIA FLEX-FLEX ACTIONSCRIPT LANGUAGE, Reference

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180 Chapter 5: ActionScript Core Language Elements
interface
Availability
Flash Player 6.
Usage
interface InterfaceName [extends InterfaceName ] {}
Description
Keyword; defines an interface. An interface is similar to a class, with the following
important differences:
•
Interfaces contain only declarations of methods, not their implementation. That is, every class
that implements an interface must provide an implementation for each method declared in
the interface.
•
Only public members are allowed in an interface definition; instance and class members are
not permitted.
•
The
get
and
set
statements are not allowed in interface definitions.
FFor more information, see “Creating and using interfaces” on page 58 .
Example
The following example shows several ways to define and implement interfaces:
(in top-level package .as files Ia, B, C, Ib, D, Ic, E)
// filename Ia.as
interface Ia
{
function k():Number; // method declaration only
function n(x:Number):Number; // without implementation
}
// filename B.as
class B implements Ia
{
function k():Number {return 25;}
function n(x:Number):Number {return x+5;}
}
// script file
var mvar:B = new B();
trace(mvar.k()); // 25
trace(mvar.n(7)); // 12
// filename c.as
class C implements Ia
{
function k():Number {return 25;}
} // error: class must implement all interface methods
// filename Ib.as
interface Ib
{
CHAPTER 5
ActionScript Core Language Elements