Pushing the boundaries

…couldn’t be any simpler!

native function

Posted by vijayram on January 31, 2007

Ok, this is a cool modifier. While I was looking through the notes on ActionScript 3.0, I did notice a reserved keyword called “native”. I had worked with native implementation in JAVA(JNI), so this really got me excited.Why?!

The reason being, the use of native functions indicates that the method is implemented externally. In a DLL maybe? ;). So, there maybe possiblities to call native windowsAPI from the swf…hmmm. Using this abstract modifier means that the method implementation is not provided in the class.Because an external method declaration provides no actual implementation, there is no method body; the method declaration simply ends with a semicolon and there are no braces ({ }) following the signature.

native function functionName();
class className {
native function methodName();

So I started rummaging through the Flash Player code, and voila they use native functions as a part of implementation. What this means is that the native functions available to the Virtual Machine is called for through this function call using ActionScript.

//pseudo-final – no user class can extend Class
public dynamic class Class
// {DontEnum,DontDelete,ReadOnly}
public native final function get prototype()

// Class.length = 1 per ES3
// E262 {ReadOnly, DontDelete, DontEnum }
public static const length:int = 1;

The above is the actual code for a top level Class construct in the Virtual Machine which is available on tamarin.
Ok, the next obvious step, can I call for it from my code and override it if possible?!

Sadly not!!!! It turns out that Flash Player uses this internally and I cannot use it in my code as explained here.


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