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() {
            $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);
        }
    }
?>