ActionScript 3.0 Design Patterns.pdf - VideoTutorials-bg.com

Example 1-18. Guitar.as (continued)
}
}
public function playInstrument(strum:String):void
{
trace("Playing my air "+ strum);
}
Looking at Example 1-19 and the Bongo class, at first you may think that the method
is built incorrectly. It’s wholly different from the Guitar class in its details, but the
method’s signature is identical.
Example 1-19. Bongo.as
package
{
import flash.media.Sound;
import flash.media.SoundChannel;
import flash.net.URLRequest;
}
public class Bongo implements BandFace
{
}
public function Bongo( ){}
private var sound:Sound;
private var playNow:SoundChannel;
private var doPlay:URLRequest;
public function playInstrument(strum:String):void
{
sound=new Sound( );
}
doPlay=new URLRequest(strum);
sound.load(doPlay);
playNow=sound.play( );
Remember, when working with interfaces, the number of methods in an interface
can be many or few, but as long as each implementation of the interface includes
every method in the interface and maintains the structure, everything works fine.
You may be wondering where the inheritance is. Given the fact that you must build
all the interface’s methods, it looks more like a customization than an inheritance.
However, the BandFace subclasses all inherit its interfaces. So essentially, the subclasses
inherit the interface but not the implementation.
Finally, to test the application, the MakeSound class, listed in Example 1-20, tests both
classes and their very different constructions of the single method from the BandFace
Inheritance | 29