Question

I’m new to Actionscript programming. I’m trying to figure out what is the best way to return multiple variables, each having a different data type, from a function. For example, if a function needs to return variable aa ( a string) and variable bb (a number).

The function I’m using just crunches a lot of math, and doesn’t relate to an object in a GUI. One method I got from a Google search used an Object, but as (I think) this requires me to create a class, I wondered if there was a simpler way. Since an array can hold elements of different data types, perhaps this is a simpler approach (?).

Here’s an example mxml and AS3 file taken from “Flash Builder 4 and Flex 4 Bible” by David Gassner.

file: Calculator.mxml

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
  xmlns:s="library://ns.adobe.com/flex/spark" 
  xmlns:mx="library://ns.adobe.com/flex/mx" 
  xmlns:components="components.*">
  <fx:Script source="calculator.as"/>
  <s:Panel title="Calculator" horizontalCenter="0" top="20">
    <s:layout>
      <s:VerticalLayout horizontalAlign="center"/>
    </s:layout>
    <mx:Form>
      <components:ButtonTile id="input" 
        select="selectHandler(event)" 
        calculate="calculateHandler(event)"/>
      <mx:FormItem label="Entry:">
        <s:TextInput text="{currentInput}" editable="false" width="80"/>
      </mx:FormItem>
      <mx:FormItem label="Total:">
        <s:TextInput text="{currentResult}" editable="false" width="80"/>
      </mx:FormItem>   
    </mx:Form>

file: calculator.as

//ActionScript code for Calculator.mxml
[Bindable]
private var currentResult:Number=0;
[Bindable]
private var currentInput:String="";

private function calculateHandler(event:Event):void
{
  currentResult += Number(currentInput);
  currentInput="";
}
private function selectHandler(event:TextEvent):void
{
  currentInput += event.text;
}

Could someone illustrate how to modify one of the functions in calculator.as, just as an example how to return two values, where one is a number and the other a string? Is there an obvious best-way to do this, or, what would be the pros/cons of different approaches? Thanks in advance!

Answer 1

You could just simply return an Object which is dynamic and thus lets you define values on the fly, like this:

return {something: "string", another: 18};

Or:

var obj:Object = {};

obj.something = "string";
obj.another = 18;

return obj;

But in my opinion this is really poor practice (especially if your function is to return the same sets of information with new values).

I’d take this route:

You can create your own class that holds various properties. From there you can return an instance of this object with the properties defined as you wish.

Example:
This would be in an external file called CollisionData.as

package
{
    public class CollisionData
    {
        public var x:Number = 0;       // X coordinate of the collision
        public var y:Number = 0;       // Y coordinate of the collision
        public var angle:Number = 0;   // Collision angle
    }
}

And your function could be:

function calculate():CollisionData
{
    var col:CollisionData = new CollisionData();

    // determine collision details
    col.x = 115;
    col.y = 62;
    col.angle = 0.345;

    return col;
}

Then you can create your own collision data based off the result:

var myCollision:CollisionData = calculate();

And fetch the details:

trace(
    myCollision.x,
    myCollision.y,
    myCollision.angle
);