Gotcha with ActionScript ‘const’

ActionScript (like JavaScript) lets you access object properties using two different notations. Consider the following class

class A
{
     public const CONSTANT:int = 34;
}

var a:A = new A();

The CONSTANT property of object a can be referred using the following two formats:

• a.CONSTANT
• a["CONSTANT"]

Since CONSTANT is declared using const, it cannot be assigned a new value later on. So the following code doesn’t compile (as expected):

a.CONSTANT = 23;

However, the following code compiles and only throws an exception at run-time:

a["CONSTANT"] = 23;

Beware of this behavior of ActionScript when using const in your code!