note 88082 added to function.set-exception-handler

Thanks to mastabog we know that throwing an exception within the exception handler will trigger a fatal error and a debugging nightmare. To avoid throwing an exception within there should be easy. However, if you use a custom error handler to convert errors to ErrorExceptions suddenly there are a multitude of new ways to accidentally throw exceptions within the exception handler. <?php function error_handler($code, $message, $file, $line) { if (0 == error_reporting()) { return; } throw new ErrorException($message, 0, $code, $file, $line); } function exception_handler($e) { // ... normal exception stuff goes here print $undefined; // This is the underlying problem } set_error_handler("error_handler"); set_exception_handler("exception_handler"); throw new Exception("Just invoking the exception handler"); ?> Output: Fatal error: Exception thrown without a stack frame in Unknown on line 0 The best way I have found to avoid this is to wrap up everything in the exception handler in a try/catch block. <?php function exception_handler($e) { try { // ... normal exception stuff goes here print $undefined; // This is the underlying problem } catch (Exception $e) { print get_class($e)." thrown within the exception handler. Message: ".$e->getMessage()." on line ".$e->getLine(); } } ?> Output: ErrorException thrown within the exception handler. Message: Undefined variable: undefined on line 14 This speeds up debugging and offers some scalability to any other exceptions accidentally thrown within the exception handler. Another solution is to restore the error handler at the beginning of the exception handler. While this is a silver bullet in terms of avoiding the ErrorExceptions, debugging messages then rely on the error_reporting() level and the display_errors directive. Why mention this? It might be preferable for production code since we care more about hiding errors from users than convenient debugging messages. ---- Server IP: 117.55.229.1 Probable Submitter: 130.194.81.30 ---- Manual Page -- http://www.php.net/manual/en/function.set-exception-handler.php Edit -- https://master.php.net/note/edit/88082 Del: integrated -- https://master.php.net/note/delete/88082/integrated Del: useless -- https://master.php.net/note/delete/88082/useless Del: bad code -- https://master.php.net/note/delete/88082/bad+code Del: spam -- https://master.php.net/note/delete/88082/spam Del: non-english -- https://master.php.net/note/delete/88082/non-english Del: in docs -- https://master.php.net/note/delete/88082/in+docs Del: other reasons-- https://master.php.net/note/delete/88082 Reject -- https://master.php.net/note/reject/88082 Search -- https://master.php.net/manage/user-notes.php