var className:String = 'com.firstrowria.SampleClass';
var classReference:Class = Class(getDefinitionByName(className));
var classInstance:Object = new classReference();
var functionName = 'sampleFunction';
var functionName2 = 'sampleFunctionWithParameter';
classInstance[event.functionName]();
classInstance[event.functionName2]('this is my string parameter');