$city = "San Francisco";
$state = "CA";
$event = "SIGGRAPH";
$location_vars = array("city", "state");
// compatible: compact("event", "nothing_here", $location_vars);
$result = Vars::compact(get_defined_vars(), "event", "nothing_here", $location_vars);
print_r($result);
/*
Array
(
[event] => SIGGRAPH
[city] => San Francisco
[state] => CA
)
*/