Question

If I set up a function that accepts a callback:

function loadSomething(path:String, callback:Function):void;

And that callback should accept a given type, for example a String to represent some loaded information:

function onLoaded(response:String):void;

// Load some data into onLoaded.
loadSomething("test.php", onLoaded);

Is it possible to assess the function that will be used for callback and ensure that it has both a given amount of arguments and that the argument accepts the correct type? e.g.

function broken(arg:Sprite):void;

// This should throw an error.
loadSomething("test.php", broken);

Answer 1

I don’t think you should bother doing this kind of check as it would create an uncessary overhead. You can simply throw the exception when you do the callback:

try {
    doCallback(response);
} catch(e:*) {
    trace('Incompatible callback');
}

If you really want to do the check, you might be able to do it using reflection. Just call describeType(callback) from flash.utils and parse the XML.