How to extend system classes

[birnerseff]

Hi,

just an example: I am using lots of arrays in my code, and so repeat the stanza

somearray[somearray.length-1]

all over the place.

Now, I could do something like

public dynamic class MyArray extends Array

{    public function get last():*

     {    return this[this.length-1];

     }

}

and replace all instances of new Array() by new MyArray().

This would allow to use

somearray.last

However, this would lose the shortcut [], and the "last" accessor would not be available on arrays set up by system code (say as part of data

collections)

There are similar examples for static functions that I would like to add to some classes. I could, of course, collect them into a class MathUtil or 'GeomUtil,

but I would prefer to relate them to, say Point or Vector3D

I have seen "prototype chain" etc mentioned, would that help?

[kglad]

create a static method:

package {

    public class A {

        public static function last(a:Array):*{

            return a[a.length-1];

        }

    }

}

[birnerseff]

Hi,

well that would give me

A.last(myarray)

instead of the desired

myarray.last

Probably even that makes code somewhat more readable

[Guest]

>>However, this would lose the shortcut [], and the "last" accessor would not be available on arrays set up by system code (say as part of data collections)

I would say not an issue to both of those. When do you really use []? I never use it... and who cares about arrays set up by system code? This solves your issue... but while I don't see your first solution as a problem, I would use kglads way - and do actually. I have an array utilities class and make use of it exactly like that: A.last(myarray) and I do think it makes the code more readable as well. Just my .02

[birnerseff]

Hi,

well, I really prefer [] over new Array() and {} over new Object() ....

I have one class that is declared

public dynamic class something extends Array

For the moment I have added

public function get lastsomething():*

to it. I found that telling plain arrays and this special construct apart (in code just a few weeks old) was not that easy, so I will probably use distinctive member names more often