The best practice would be to use traditionnal getters and setters, because of introspection or reflection. There is a way in PHP (exactly like in Java) to obtain the name of a method or of all methods. Such a thing would return "__get" in the first case and "getFirstField", "getSecondField" in the second (plus setters).
More on that: http://php.net/manual/en/book.reflection.php