Object Function-call handling in PHP5

This is a toughy I've been working over for a bit. I was wondering if there is a way to cause objects to have certain behaviors when builtin functions are called, or maybe a way of setting, for example, a "primary" string which is used whenever a function requiring a string calls it. IE: Class myString { Public $Value; Function __construct($Value) { $this->Value = $Value; } } $MyString = new myString("Hello World"); Print($MyString); //Wondering if I can get this to return "Hello World" Printing is probably a weak example because you could just use Print($MyString->Value); but there are reasons why I would want it this way.