AS 3.0 Coming From 2.0 - Article 3

Lesson 7: Speed Through Types

First thing first, what on earth is typing? Well, I'm not talking about entering keystrokes on a keyboard. I'm talking about giving variables a defined type. By type, I mean defining whether it's a String, or a Number, or any other different type of object. ActionScript does not require you to give variables a type, so you may ask "Why would we do it then?" Speed. When you make an untyped variable (any variable that you do not specifically give a type) Flash doesn't really define what it is, and has to treat it as if it could be any type. This slows things down a lot. If you tell Flash what it is, then Flash can do what it needs to do with it, and be on it's merry way to the next line of code much faster.

1. // this is an untyped variable:
2. var slowVar = "myString";
3. // by telling Flash that it is a String, it can handle it much faster, this is a typed variable:
4. var fastVar:String = "myString";

1. // this is an untyped function:
2. function slowFunc()
3. {
4.     return 100;
5. }
6. // by telling Flash that it returns a Number, it can go faster, this is a typed return for a function:
7. function fastFunc():Number
8. {
9.     return 100;
10. }
11. //You can also define that the function will not have a return value using "void":
12. function fastFuncWithoutReturn():void
13. {
14.     // lines of code...
15. }

1. // colors should be uint:
2. var red:uint = 0xFF0000;
3. // most loops should use int, since it is usually only whole number math it will be faster:
4. for (var i:int = 0; i < 50; i++)
5. {
6.     doSomethingWith(i);
7. }
8. // Most normal math should use Number:
9. function half(numIn:Number):Number
10. {
11.     var numOut:Number = numIn / 2;
12.     return numOut;
13. }