public function __isset($property = null)
	{
		if (!property_exists(__CLASS__, $property) || $property{0} == '_')
		{
			if (empty($property))
			{
				$property = '(null)';
			}

			$this->_error("Cannot access property " . __CLASS__ . "::$" . $property, E_USER_ERROR);
			die();
		}

		return isset($this->$property);
	}