is_ref?

Is there a way to check whether a given variable is a reference in php? I.e. $foo="hi"; $bar=&$foo; if (is_ref($bar)) echo "ref"; Corollary question: What happens to references after a cycle of being stored in and retrieved from the $_SESSION? Do I get copies now, or do I still have a reference? Also, does PHP have the notion of class variables as in Java? I.e. a shared variable between all objects of a given class? It appears that we only have what would be called 'instance variables' in Java. Is this correct? Thanks Alok