DatabasePDO.class.php

<?php

class DatabasePDO extends PDO {

   protected static $singleton = NULL;

   public static function singleton(){
      if(is_null(static::$singleton))
         static::$singleton = new static();

      return static::$singleton;
   }

   public function __construct() {
       // $db = new PDO("sqlite::memory");

       $connectionString = "mysql:host=". DB_HOST;

       if(defined('DB_PORT'))
           $connectionString .= ";port=". DB_PORT;

       $connectionString .= ";dbname=" . DB_DATABASE;
       $connectionString .= ";charset=utf8";

      parent::__construct($connectionString,DB_USERNAME,DB_PASSWORD);
      $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
   }
}