Have you ever looked at the returned value of the function flash.utils.getQualifiedClassName() and wondered why it includes :: between the package and the class name? For example, if you pass in a MouseEvent instance, you'll get the string value "flash.events::MouseEvent". The first time I tried it, I expected to receive "flash.events.MouseEvent" with a . because that's how you reference a packaged class in an import statement. I always thought the difference was a little strange, but I just shrugged and went about my business. Today, though, my mind must have been feeling a little extra clever than ususal because it suddenly dawned on me: you use :: as an operator in ActionScript 3 to access a namespace.
With one simple test, it became unquestionably clear that packages in ActionScript 3 are really an abstraction built on top of namespaces. Try running the following code using the Flex SDK or the Flash authoring tool:
namespace flash_events = "flash.events"; trace( flash_events::MouseEvent ); //output: [class MouseEvent]
No import needed!
I imagine this has ECMAScript 4 roots. In general, many of the OOP features of AS3, like class and package syntax, are considered syntactic sugar. How can AS3 developers benefit from this knowledge? I have no idea, but it's one of those discoveries that whispers, "someday, you may need me".
[...] that :: part of the fully-qualified class name? Shouldn’t it be . instead? Check out my post Packages are actually namespaces in ActionScript 3 to learn [...]
You can benefit from this, if you use Flex: Flex uses an namespace called mx_internal to hide stuff from the user. If you use the mx_internal namespace, you can access these hidden properties of Flex components. For example i love to use mx_internal::$addChild method – its for adding a non-Flex child to a Flex component. Since you add it directly, Flex wont do anything to this component.
Basically Adobe uses this namespace thing to hide functions in a class without making them private.
I think you misunderstood the point of this post, sydd. It wasn’t to introduce namespaces in their typical usage (like how Flex classes use mx_internal). Instead, it shows how a very core part of ActionScript 3, namely packages, is actually using namespaces behind the scenes. Many developers don’t realize that.
One more thing, sydd. Rather than calling $addChild(), you should use rawChildren.addChild(). It’s a fully supported public API that is designed for the same thing that you’re trying to do.