$state = 'foo'; 
$running = 1;
while($running) {
   if ($state eq 'foo') {
        # do stuff
        $nextstate = 'bar';
   }
   elsif ($state eq 'bar') {
        # do stuff 
        $nextstate = 'baz';
   }
   elsif ($state eq 'baz') {
        # do stuff
        $running = 0;
   }
   $state = $nextstate;
}