Better Casting Through ActionScript 3

In ActionScript 2, you could cast an object to a type by using:

ClassName(ObjectToCast)

This syntax is somewhat different than what you have in other languages. Usually in C-like languages you'll use something like this:

(ClassName)ObjectToCast

It doesn't seem a lot different, does it? But there is a problem with the way casting is done in ActionScript 2. ActionScript 2 also contains global creation functions for native data types-that look identical to typecasting syntax. The example I would continuously encounter was when I had a method that returned an object that I knew was an array. Let's look at an example. For the sake of argument say I have a method called getObject() that returns any object type-and I want to return an array from it. According to ActionScript 2 typecasting, I should be able to do something like this:

var MyObject:Array;
MyObject = Array(getObject());

But since global native data type functions take precedence, this doesn't actually cast the object from the getObject() method to an array-instead it creates a brand new array. You might be thinking this doesn't sound too bad-you're creating a new array of the returned array. Unfortunately, the new array you're creating isn't a replica of the array being returned from getObject()-its a new array with the array being returned from getObject() as the first element. Bleh! There is no good way to get around this in ActionScript 2-basically you're stuck.

In ActionScript 3, there is an easy way to solve this problem. ActionScript 3 does support the ActionScript 2 method of typecasting (with the slight difference that type exceptions are now thrown instead of the variable you're casting being set to null if a cast failure occurs) but it also introduces a new typecasting mechanism using the as keyword. You're basically saying "treat my object as this type".

To solve the problem related above, you can do this:

var MyObject:Array;
MyObject = getObject() as Array;