PHPカスタム関数のエラー処理方法

<?php
error_reporting(E_ALL);
function ErrHandler($errorno, $errorstr, $errorfile, $errorline)
{
  $display = true;
  $notify = false;
  $halt_script = false;
  $error_msg = "<br>The $errorno error is occurring at $errorline in
  $errorfile<br>";
  switch($errorno)
  {
   case E_USER_NOTICE:
   case E_NOTICE:
   $halt_script = false;
   $notify = true;
   $label = "<B>Notice</B>";
   break;
   case E_USER_WARNING:
   case E_WARNING:
   $halt_script = false;
   $notify = true;
   $label = "<b>Warning</b>";
   break;
   case E_USER_ERROR:
   case E_ERROR:
   $label = "<b>Fatal Error</b>";
   $notify=true;
   $halt_script = false;
   break;
   case E_PARSE:
   $label = "<b>Parse Error</b>";
   $notify=true;
   $halt_script = true;
   break;
   default:
   $label = "<b>Unknown Error</b>";
   break;
  }
  if($notify)
  {
   $msg = $label . $error_msg;
   echo $msg;
  }
  if($halt_script) exit -1;
}
$error_handler = set_error_handler("ErrHandler");
echo "<BR><H2>Using Custom Error Handler</h2><BR>";
trigger_error("<BR>Error caused by E_USER_NOTICE</BR>", E_USER_NOTICE);
trigger_error("<BR>Error caused by E_USER_WARNING</BR>", E_USER_WARNING);
trigger_error("<BR>Error caused by E_USER_ERROR</BR>", E_USER_ERROR);
trigger_error("<BR>Error caused by E_PARSE</BR>", E_PARSE);
?>