Storing functions with arguments as String

I need to store a function with arguments in one string.

Without arguments, you can simply do sth. like that:

functionName:String = "hello";

this[functionName]()

function hello():void{

   "Hello, World";

}

But as soon as you introduce arguments it`s getting tricky.

I came up with this:

function getArgsFromFunction(_function: String): Array {

    var argstart: int = _function.indexOf("(");

    var argend: int = _function.indexOf(")");

    var argstring: String = _function.substr(argstart + 1, argend - argstart - 1);

    var args: Array = argstring.split(",");

    return args;

}

function getNameFromFunction(_function: String): String {

    var nameEnd: int = _function.indexOf("(");

    var nameString: String = _function.substr(0, nameEnd);

    return nameString;

}

var f:String = "showMessage(A,B)";

function showMessage(_args: Array): void {

    trace(_args);

}

var _funct: Function = this[getNameFromFunction(f)];

_funct.call(this, getArgsFromFunction(f));

but its not very versatile, not very robust, and seems unnecessarily complicated.

Anyone know a quicker way to get this done?