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Debugging in local enviroment [basic]

In previous post I've described some very basic debugging methods for already released products - while we are on topic of debugging, lets have a look at some popular and easy methods for fixing errors in local environment. Of course everything comes down to what we want to do with our application, but there will be always room for those universal tricks:

1. Execution speed time.
Skipping past the fact you should build your application also considering slower computers, speed measuring is a great way to test algorithms, especially if we know how much time they need beforehand. For more prominent results it's usually a good idea to add a loop:

public static function measureProcessTime(fun:Function, repeat:int = 10):Number {
	var time:Number = getTimer();
	for(var i:int = 0; i < repeat; i++) {
	return getTimer() - time;
Note that local functions are especially useful here as Flash allows their creation pretty much everywhere, allowing us to test any part of the code by simply enclosing it in the following way:
var someVar:Number = 0;
someVar = 1;
function debug() {
	var otherVar:Number = 10;
	someVar += otherVar;

2. Loop traversing.
This is another neat neat way to test algorithms. Basically the idea here is to display one single point in a loop, but with ability to move that point around. Example implementation:

private static var DEBUG_COUNT:int = 0;
private static var DEBUG_STEP:int = 0;
public static function nextStep():void {
public static function prevStep():void {
public static function resetDebug():void {
public static function countDebug():Boolean {
Functions nextStep and prevStep are meant to be connect to the arrow keys, allowing us to traverse the loop. The resetDebug function should be called before the loop we want to test. Finally the countDebug function which will return true when our loop reaches the selected step. Although it doesn't seem like much, loop traversing can be incomparable debugging tool. Good example of this is a line drawing algorithm:
(Use the up and down arrow keys to move around the loop)

3. Graphics overlay.
I think no one will disagree it's easier to see data in graphic representation rather than list of variables, which is why every application should always have some kind of way to draw (using Graphics class) information above every other object. This can be easily done by holding the main application in a "container" MovieClip, while having a single Sprite one step above it, which will be empty but accessible from anywhere in the application:
public static debug:Sprite;
public function DocumentClass() {
	var main:MyApplication = new MyApplication();

	var debug:Sprite = new Sprite();
Now we just need to write to start drawing over everything else. Personally I like to use it as a way to check hit-boxes of objects on the screen:

Confirm the image code:confirm image