if(function_exists($request)) {
/** one, two are given args */
call_user_func_array($request, array("one", "two"));
}
elseif(class_exists($request)) {
/** Call the class */
$foo = new foo();
/** Call the method bar from class foo with arguments three and four */
call_user_func_array(array($foo, "bar"), array("three", "four"));
}