Still confused about vars in OOP

programming flash
1

Hello All,

As my exams are nearly over (just 2 weeks ^^ ) I decided as a break between revision I would look back to AS3 and OOP and once again I have Confused myself =[

All I Want To Do Is:

Access a variable from another class. To my very inexperienced mind this sounds simple…

Here is my example classes.

ActionScript Code:
[LEFT][COLOR=#808080]*//Document Class*[/COLOR]

package [COLOR=#000000]{[/COLOR]
[COLOR=#0000FF]import[/COLOR] flash.[COLOR=#000080]display[/COLOR].*;
[COLOR=#0000FF]import[/COLOR] com.[COLOR=#0000FF]xml[/COLOR].[COLOR=#000080]xmlLoad[/COLOR];

[COLOR=#0000FF]public[/COLOR] [COLOR=#000000]**class**[/COLOR] main [COLOR=#0000FF]extends[/COLOR] [COLOR=#0000FF]MovieClip[/COLOR] [COLOR=#000000]{[/COLOR]

    [COLOR=#0000FF]public[/COLOR] [COLOR=#000000]**var**[/COLOR] _targetURL = [COLOR=#FF0000]"Musicinfo.xml"[/COLOR];[COLOR=#808080]*//This is the var that i want to share*[/COLOR]
    [COLOR=#000000]**var**[/COLOR] getXML:xmlLoad = [COLOR=#000000]**new**[/COLOR] xmlLoad[COLOR=#000000]([/COLOR][COLOR=#000000])[/COLOR];   

     [COLOR=#0000FF]public[/COLOR] [COLOR=#000000]**function**[/COLOR] main[COLOR=#000000]([/COLOR][COLOR=#000000])[/COLOR] [COLOR=#000000]{[/COLOR]
    [COLOR=#808080]*// Do stuff with the xml here*[/COLOR]
    [COLOR=#000000]}[/COLOR]
[COLOR=#000000]}[/COLOR]

[COLOR=#000000]}[/COLOR]

[COLOR=#808080]//xml Loader class[/COLOR]
package com.[COLOR=#0000FF]xml[/COLOR][COLOR=#000000]{[/COLOR]
[COLOR=#0000FF]import[/COLOR] flash.[COLOR=#000080]events[/COLOR].;
[COLOR=#0000FF]import[/COLOR] flash.[COLOR=#000080]net[/COLOR].;
[COLOR=#0000FF]import[/COLOR] flash.[COLOR=#0000FF]xml[/COLOR].*;

[COLOR=#0000FF]public[/COLOR] [COLOR=#000000]**class**[/COLOR] xmlLoad [COLOR=#000000]{[/COLOR]
    [COLOR=#0000FF]public[/COLOR] [COLOR=#000000]**function**[/COLOR] xmlLoad[COLOR=#000000]([/COLOR][COLOR=#000000])[/COLOR] [COLOR=#000000]{[/COLOR]
        [COLOR=#000000]**var**[/COLOR] fileURL = _targetURL[COLOR=#000000]([/COLOR][COLOR=#000000])[/COLOR]; [COLOR=#808080]*//This is the var from the Document Class*[/COLOR]
        [COLOR=#0000FF]trace[/COLOR][COLOR=#000000]([/COLOR]fileURL[COLOR=#000000])[/COLOR];
        [COLOR=#000000]**var**[/COLOR] xmlFile:URLRequest = [COLOR=#000000]**new**[/COLOR] URLRequest[COLOR=#000000]([/COLOR]fileURL[COLOR=#000000])[/COLOR];
        [COLOR=#000000]**var**[/COLOR] _loader:URLLoader = [COLOR=#000000]**new**[/COLOR] URLLoader[COLOR=#000000]([/COLOR]xmlFile[COLOR=#000000])[/COLOR];
        _loader.[COLOR=#000080]addEventListener[/COLOR][COLOR=#000000]([/COLOR]Event.[COLOR=#000080]COMPLETE[/COLOR], makeXML, [COLOR=#000000]**false**[/COLOR], [COLOR=#000080]0[/COLOR], [COLOR=#000000]**true**[/COLOR][COLOR=#000000])[/COLOR];
        [COLOR=#000000]**function**[/COLOR] makeXML[COLOR=#000000]([/COLOR]evt:Event[COLOR=#000000])[/COLOR] [COLOR=#000000]{[/COLOR]
            [COLOR=#0000FF]trace[/COLOR][COLOR=#000000]([/COLOR]evt.[COLOR=#0000FF]target[/COLOR].[COLOR=#0000FF]data[/COLOR][COLOR=#000000])[/COLOR];
        [COLOR=#000000]}[/COLOR]
    [COLOR=#000000]}[/COLOR]
[COLOR=#000000]}[/COLOR]

[COLOR=#000000]}[/COLOR]
[/LEFT]

Now I do think that i could make that variable in the xmlLoad class but I just simply want to know if sharing vars like that could be done and a working example would go down very nicely too xD

I though useing a get function would work but it didn’t

Thanks if you can help me understand this

2

_targetURL is a property of the class ‘main’ in the code you posted, so your xmlLoad class would have to have an instance of ‘main’ to access it.

//Document Class
package {
	import flash.display.*;
	import com.xml.xmlLoad;

	public class main extends MovieClip {

		public var _targetURL = "Musicinfo.xml";//This is the var that i want to share
		var getXMLmlLoad;
	
		public function main() {
			getXMLmlLoad = new xmlLoad(this);
			// Do stuff with the xml here
		}
	}
}

//xml Loader class
package com.xml{
	import flash.events.*;
	import flash.net.*;
	import flash.xml.*;
	
	public class xmlLoad {
		public function xmlLoad(documentClass:main) {
			var fileURL = main._targetURL; //This is the var from the Document Class
			trace(fileURL);
			var xmlFile:URLRequest = new URLRequest(fileURL);
			var _loader:URLLoader = new URLLoader(xmlFile);
			_loader.addEventListener(Event.COMPLETE, makeXML, false, 0, true);
			function makeXML(evt:Event) {
				trace(evt.target.data);
			}
		}
	}
}
3

im not going to write it for you but what you need to do is asign getters and setters, heres a quick ex…

var _myVar:int
public function get myVar():int
{
return _myVar
}
public function set myVar(newValue:int):void
{
_myVar = newValue
}

then you can use myVar across any class
hope that helps:thumb2:

4

[quote=GrndMasterFlash;2337526]im not going to write it for you but what you need to do is asign getters and setters, heres a quick ex…

var _myVar:int
public function get myVar():int
{
return _myVar
}
public function set myVar(newValue:int):void
{
_myVar = newValue
}

then you can use myVar across any class
hope that helps:thumb2:[/quote]

That’s not really the case. Getters and setters are helpful tools, but they don’t explicitly have anything to do with accessing your variables across classes. They should be used to ensure proper encapsulation in many cases, but that wasn’t the question.

Krilnon’s example is more accurate, given the question.

5

Krilnon,

What exactly do you mean by:

xmlLoad class would have to have an instance of ‘main’ to access it.

And also what exactly does this do?

[COLOR=#0000FF]public[/COLOR] [COLOR=#000000]function[/COLOR] xmlLoadCOLOR=#000000[/COLOR] [COLOR=#0000FF][/COLOR][COLOR=#000000][/COLOR]

As I have no understanding of what the code Is meant to do I simply tried to copy and paste it into CS3 but then got a error (1119: Access of possibly undefined property _targetURL through a reference with static type Class.) on this line.

var fileURL:String = main._targetURL;

Sorry i didn’t get it first time ='[

6

Hey Nikomax,

Krilnon included a parameter to pass the document class to the xmlLoad class. I think he meant the line to be:


var fileURL:String = documentClass._targetURL;

… but I could be wrong. Give that a shot instead.

7

Wooo it worked =D Thank you guys!

Just to clarify though, where the instance of the document class was passed like this [xmlLoad(documentClass:main)] can any other classes be referenced the same way?

Thanks for the help!!
<3

8

Okay, well, he actually just added that in there as a parameter, the syntax isn’t strict. It could have said:


public function xmlLoader(fooBarRabbit:*):void
//....
var fileURL:String = fooBarRabbit._targetURL;

and it still would have worked. What he did is pass the parent class as a parameter.

9

Ah yes, that was my mistake. :trout: Thanks for correcting it. :slight_smile: