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

Example 3-12. Tuner.as
}
}
}
//Stop Play
public function stopMe ( ):void
{
if (_goChannel != null)
{
_goChannel.stop ( );
}
}
class PrivateClass
{
public function PrivateClass ( )
{
trace ("PrivateClass called");
}
}
The first thing to note about this Singleton script is that it imports packages and
classes. Up to this point, all of the imports were done in the scripts that called the
Singleton class. However, whenever a method or property has a reference, including
abstract ones, to a class in a package, it needs to import that class. Likewise, you’ll
see that the class (DoMusic) that implements the Singleton class (Tuner) requires no
further import of the objects associated with the packages and classes already
imported in the Singleton class.
Because this application simply makes sure that only one MP3 file is played at any
time, the Singleton implementation is very simple. Example 3-13 shows the code for
this class:
Example 3-13. DoMusic.as
package
{
import flash.display.Sprite;
public class DoMusic extends Sprite {
public function DoMusic( ) {
var playOne:Tuner = Tuner.getInstance( );
//Use any MP3 file you have available
playOne.playMe("blues.mp3");
}
}
}
Save Example 3-13 as DoMusic.as in the same folder as Tuner.as. Open a Flash document
file, type DoMusic in the Class document window in the Properties panel, and
save it as Music.fla in the folder with the two ActionScript files. Finally, place any
When to Use the Singleton Pattern | 119