Question

In ActionScript 3, there are some classes that will represent a value rather than the class itself. It’s hard to explain properly what I mean, so take this example:

var str:String = "something";
var mc:MovieClip = new MovieClip();

trace(str); // something
trace(mc); // [object MovieClip]

You’ll notice that the first trace outputs a value, rather than [object String]. Ontop of this, I can still make use of methods of String, like this:

var ar:Array = str.split('s');

Even though in a way you could almost read the above as:

"something".split('s');

I have a class AvLevelData that has some methods that deal with level data (which is essentially a String). At the moment there is a property data:String which represents the core level data.

The question I have is – can I replicate the behaviour of String in that when I trace or assign an instance of AvLevelData, the result is actually the String data.

For example, at the moment I need to go:

var levelData:AvLevelData = new AvLevelData();
trace(levelData.data);

To get the data. I instead want to be able to simply do the following:

var levelData:AvLevelData = new AvLevelData();
trace(levelData); // some level data string

Is this possible?

Answer 1

If you wan’t your object to trace out your own fabricated string then you must implement a toString() function on your AvLevelData class.

In your example above, the MovieClip trace outputs: [Object MovieClip]; this comes from the default toString() implementation for Object (found on Object.prototype) . Note, you cannot override toString() as it only exists on the prototype of Object (remnants of the AS2/Javascript world), all you need to do is provide your own implementation with the same name. For instance:

public function toString():String {
   return "MyCustomObjectString";
}