Cleanup

exam/classes/Database/Database.php

@@ -3,17 +3,28 @@
 namespace Khofmann\Database;
 
 use PDO;
-use Config\Config;
+use Khofmann\Config\Config;
+use Exception;
 
 class Database extends PDO
 {
   private static array $instances = [];
 
-  protected function __construct(string $dsn, string $username = null, string $password = null, array $options = null)
+  private function __construct(string $dsn, string $username = null, string $password = null, array $options = null)
   {
     parent::__construct($dsn, $username, $password, $options);
   }
 
+  private function __clone()
+  {
+    throw new Exception("Cannot clone a singleton.");
+  }
+
+  private function __wakeup()
+  {
+    throw new Exception("Cannot unserialize a singleton.");
+  }
+
   public static function getInstance(): Database
   {
     $cls = static::class;