Emulating a class destructor

Hi there!, I'm trying to emulate a class destructor, according to the PHP documentation I can emulate this by using a call to register_shutdown_function(), containing the function to be called upon shutdown. While this apparently works outside a class, I want to use it inside a class, in other words I want to have something like this: class cRoute{ function cRoute(){ //register the shutdown function in case people who use this class dont call the appropiate close methods. register_shutdown_function("cleanup()"); } function cleanup(){ //cleanup. trigger_error("Please call close() before the page ends, to prevent problems close() has been called automatically for you."); $this->close(); } function close(){ //close open sockets, etc. } } I have tried: register_shutdown_function("cleanup()"); register_shutdown_function("$this->cleanup()"); register_shutdown_function($this->cleanup()); register_shutdown_function("cDB::cleanup()"); They all return something like: Warning: Unable to call ()() - function does not exist in Unknown on line 0 If anyone has any ideas I'd appreciate the help. Thanks in advance!, Dw.