How to get current recursion level in a PHP function

If you are just looking to avoid hitting PHP's 100 level recursion limit then

count(debug_backtrace()); 

should be sufficient. Otherwise you've no choice to pass a depth argument, though the precrement operator makes it somewhat cleaner as seen in the example below.

function recursable ( $depth = 0 ) {
  if ($depth > 3) {
    debug_print_backtrace();
    return true;
  } else {
    return recursable( ++$depth );
  }
}