--- In flexcoders@yahoogroups.com, "bnsmeets" wrote:
>
> Hi all,
>
> I'm wondering if it is possible to 'hack' some sort of downcasting into AS3.
> The context is, that I am using a generated webservice proxy from Flex 3, and
> want to be able to add custom (extra) properties to the generated
> valueobjects without having to adjust the code that parses the wsdl result
> into objects.
>
> So e.g. the webservice generates the class:
>
> class A
> {
> property A;
> property B;
> }
>
> I have my own class that is:
>
> class B extends A
> {
> property C;
> }
>
> When i call the generated webservice "get all A's", it will return an array
> of "A" objects, what I am looking for is to convert that list into "B"
> objects. So the values of the properties that exist in the "A" counterpart,
> filled for a new "B" instance, with an empty "C" property.
Instead of having B extend A, instead have both A and B implement Interface I.
Then use the Decorator pattern (there's a current feature on this on InsideRIA
http://www.insideria.com/2009/10/decorator-design-pattern.html if you don't
have the book AS3 Design Patterns) to have B "wrap" an A and "reflect" the
properties that I requires it to have.
So
package {
public interface I {
function get prop1():String;
function set prop1(s:String):void;
function get prop2():String;
function set prop2(s:String):void;
}
}
package {
public class A implements I {
private var _prop1:String;
private var _prop2:String;
public function get prop1():String {
return _prop1;
}
public function set prop1(s:String):void {
_prop1=s;
}
public function get prop2():String {
return _prop2;
}
public function set prop2(s:String):void {
_prop2=s;
}
}
}
package {
public class B implements I {
private var _a:A;
private var _c:String;
public function B(a:A) {
_a=a;
}
public function get prop1():String {
return _a.prop1;
}
public function set prop1(s:String):void {
a.prop1=s;
}
public function get prop2():String {
return a.prop2;
}
public function set prop2(s:String):void {
a.prop2=s;
}
public function get c():String {
return _c;
}
public function set c(s:String):void {
_c=s;
}
}
}
Now, any code that needs type information, you'll be looking for I, not A,
because a B is not an A, it "contains" an A. For more on Interfaces, check out
http://www.insideria.com/2009/10/interfaces-and-dynamic-class-i.html or
http://flexdiary.blogspot.com/2009/01/example-of-casting-contets-of-swfloader.html
.
HTH;
Amy
