PHP 4 to 5 class issues involving static methods and $this

I have a class where I need to be able to use the methods as static methods as well as using them inside an initialized class. Here's an example of what I need to do: class my_class { var $elements = array(); // holds all of my elements function format_string($string) { // format the string... return $this->elements[] = $string; } function show_all() { return implode("\n", $this->elements); } } This worked fine in PHP 4. It silently ignored the $this->elements[] assignment in statically called methods and just returned my formatted string without any fuss. However, in PHP 5, I understand that I'm now required to declare the method format_string as public static if I want to just call my_class::format_string(), and if I want to use $elements inside a static method, it also requires being declared as static. I also understand that I can't use $this inside a statically called method. I've tried these things, but they don't seem to help. How can I rewrite my class for PHP 5 to emulate the functionality I had in PHP 4 in an error free way? -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/