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

Example 4-21. Generic concrete decoration
package
{
//Generic—NOT implemented
public class GoodEvil extends Decorator
{
private var components:Component;
public function GoodEvil(components:Component)
{
this.components=components;
}
override public function getSoul( ):String
{
return components.getSoul( ) + "|GoodEvil";
}
override public function good( ):Number
{
return +/-00 + components.good( );
}
override public function evil( ):Number
{
return +/-00 + components.evil( );
}
}
}
If you break down Example 4-21, the first part looks exactly like the previous examples.
A Component instance, components, is instantiated, and the constructor function
wraps the components object in itself:
var components:Component;
public function GoodEvil(components:Component)
{
this.components=components;
}
Next, the script re-implements the getter function, getSoul( ), to return both the current
value of the concrete component’s decorations plus its own decoration value.
Again, this is what previous examples have done.
override public function getSoul( ):String
{
return components.getSoul( ) + "|GoodEvil";
}
The next two functions add or subtract numeric values using the good( ) and evil( )
methods. Each good adds to a good and subtracts from an evil, and vice versa for a
vice—adds to evil and subtracts from good. So depending on the concrete decorator,
you add or subtract from each of the two return values, and add that to the current
value of the concrete component.
override public function good( ):Number
{
return +/-00 + components.good( );
152 | Chapter 4: Decorator Pattern