Object Copying

As we all know, this copies an object in PHP: $obj2 = $obj1 Assuming $obj1 is an object (of a class). I want this never, ever to happen unless I want it to. All the time, I run into something where PHP made a copy of my object for X odd reason -- I pass an object to a function, I put it in an array, etc etc etc. Is there a way I can have PHP warn me if an object is copied, or put that in the class code somehow? Preferable a way to fix PHP not to copy the object, but the reference. I'd settle for a warning system though.