IS 1181 IS 118 Introduction to Development Tools Chapter 7

IS 1182 Things to Cover Exception Handling  Exception Handling Concepts  Structures Try, throw, catch  The Exception Class  User Defined Exceptions  Exceptions in Bob’s Auto Parts  Other Error handling

IS 1183 Exception Handling Concepts Execute code inside of a TRY block  Try { // code to execute }  Within this code there needs to be a throw throw new Exception (‘message’, code)  And outside the code a catch catch (typehint exception)

IS 1184 Concepts - continued So:  <?php try { // some code throw new Exception(‘A terrible error has occurred’, 42); } catch (Exception $e) { echo ‘Exception ‘. $e->getCode(). ‘; ‘. $e->getMessage(0.’ in ‘. $e->getFile(). ‘ on line ‘.$e->getline(). ‘,br />’; } ?>

IS 1185 Exception class Built-in class to help called Exception  Takes two parameters – message and code getCode() getMessage() getFile() getLine() getTrace() getTraceAsString() _toString()

IS 1186 User Defined Exceptions Extend the base class Exception and add your own  <?php  class fileOpenException extends Exception  {  function __toString()  {  return 'fileOpenException '. $this->getCode() . ': '. $this->getMessage().' '.' in ' . $this->getFile(). ' on line '. $this->getLine() . ' ';  }

IS 1187 User Defined Continued  class fileWriteException extends Exception  {  function __toString()  {  return 'fileWriteException '. $this->getCode() . ': '. $this->getMessage().' '.' in ' . $this->getFile(). ' on line '. $this->getLine() . ' ';  }

IS 1188 User Defined - 3  class fileLockException extends Exception  {  function __toString()  {  return 'fileLockException '. $this->getCode() . ': '. $this->getMessage().' '.' in ' . $this->getFile(). ' on line '. $this->getLine() . ' ';  }  ?>

IS 1189 Bob’s Auto Parts <?php class fileOpenException extends Exception { function __toString() { return 'fileOpenException '. $this->getCode(). ': '. $this->getMessage().' '.' in '. $this->getFile(). ' on line '. $this->getLine(). ' '; }

IS Bob’s Auto Parts - 2 class fileWriteException extends Exception { function __toString() { return 'fileWriteException '. $this->getCode(). ': '. $this->getMessage().' '.' in '. $this->getFile(). ' on line '. $this->getLine(). ' '; }

IS Bob’s Auto Parts - 3 class fileLockException extends Exception { function __toString() { return 'fileLockException '. $this->getCode(). ': '. $this->getMessage().' '.' in '. $this->getFile(). ' on line '. $this->getLine(). ' '; } ?>

IS Where does this go? // open file for appending try { if (!($fp 'ab'))) throw new fileOpenException(); if (!flock($fp, LOCK_EX)) throw new fileLockException(); if (!fwrite($fp, $outputstring, strlen($outputstring))) throw new fileWriteException(); flock($fp, LOCK_UN); fclose($fp); echo ' Order written. '; }

IS Where does it go - 2 catch (fileOpenException $foe) { echo ' Orders file could not be opened. '.'Please contact our webmaster for help. '; } catch (Exception $e) { echo ' Your order could not be processed at this time. '.'Please try again later. '; }

IS Other Error Handling Chapter 25 discusses DEBUGGING  This is outside the scope of this course  BUT, it would be good to look at it