Try, catch tanker

PHP kode 

 $config = parse_ini('myinifile.ini');
 try {
     $db = new DatabaseMySQL($hostname, $username, $password, $database);
     $db->query('SELECT:* FROM do_error');
     
 } catch (Exception $e) {
     if($config['display_error']) {
         echo $e->getMessage();
     } else {
         echo 'Der er sket en fejl. Webmaster er underrettet';
     }
 }

PHP kode 

 <?php
 
 class DatabaseMySQL
 {
     private $activeConnection = 0;
     private $connections = array();
     private $lastQuery;
     private $messsages = array();
     
     public function __construct($hostname, $username, $password, $database)
     {
         $this->newConnection($hostname, $username, $password, $database);
     }
     
     public function __destruct()
     {
         $countConnections = sizeof($this->connections);
         
         for($i = 0; $i <= $countConnections; $i++)
         {
             @mysql_close($this->connections[$i]);
         }
     }
     
     public function closeConnection()
     {
         @mysql_close($this->connections[$this->activeConnection]);
     }
     
     public function executeQuery($queryString)
     {
         try
         {
             if(!$query = @mysql_query($queryString, $this->connections[$this->activeConnection])
             {
                 throw new Exception("The query couldn't be executed. Try again later.");
             }
             else
             {
                 $this->lastQuery = $query;
             }            
         }
         catch(Exception $e)
         {
             $this->newMsg($e->getMessage());
         }
     }
     
     public function newConnection($hostname, $username, $password, $database)
     {
         try
         {
             $this->connections[] = @mysql_connect($hostname, $username, $password);
             $thisConnection = $this->connections[count($this->connections) - 1];
             
             if($thisConnection)
             {
                 $selectDatabase = @mysql_select_db($database, $thisConnection);
                 
                 if(!$selectDatabase)
                 {
                     throw new Exception("There couldn't be established a connection to the database.");
                 }
             }
             else
             {
                 throw new Exception("There couldn't be established a connection to the DBMS.");
             }
             
             $connection_id = count($this->connections) - 1;
             
             return $connection_id;
         }
         catch(Exception $e)
         {
             $this->newMsg($e->getMessage());
         }
     }
     
     public function secureString($input)
     {
         if(get_magic_quotes_gpc())
         {
             $input = stripslashes($input);
         }
         return @mysql_real_escape_string($input);
     }
     
     public function setActiveConnection($new)
     {
         $this->activeConnection = $new;
     }
     
     private function newMsg($msg)
     {
         $this->messsages[] = $msg;
     }
 }
 
 ?>

PHP kode 

 try {
     $db = new DatabaseMySQL($hostname, $username, $password, $database);
     $db->query('SELECT:* FROM do_error');
     
 } catch (Exception $e) {
     echo $e->getMessage();
 }

Jeg ser umiddelbart et problem i at executeQuery() ikke kaster en exception. Problemet er at den kode der kalder executeQuery() skal huske at tjekke $messages for at se om udførslen gik godt. Hvis man glemmer denne stump kode, vil den kaldende kode fortsætte uvidende om at noget gik galt, hvilket i de fleste tilfælde ikke er tilsigtet.

Jeg ville lade klassen kaste en exception, og så måtte det være op til den kaldende kode at håndtere den og vælge om fejlen skal vises på skærmen, sendes i en e-mail, gemmes i en logfil eller noget helt andet.