public function __construct($name = null, $title = null, $value = null)
 {
     parent::__construct(self::$_TAGNAME, $name, $title, $value);
     $this->_params['type'] = self::$_TYPE;
     $this->add_class(self::$_CLASS);
     $this->get_container()->add_class(self::$_CONTAINER_CLASS);
     $this->set_clear_button(self::$_DEFAULT_CLEAR_BUTTON);
     $this->_date_mask = String::get('date_mask');
     if (!$this->_date_mask) {
         $this->_date_mask = self::$_DEFAULT_DATE_MASK;
     }
     $this->_date_mask = self::_prepare_format($this->_date_mask);
     $this->_date_format = String::get('date_format');
     if (!$this->_date_format) {
         $this->_date_format = self::$_DEFAULT_DATE_FORMAT;
     }
     $this->_date_format = self::_prepare_format($this->_date_format);
     if (self::$_DEFAULT_VALUE_NOW && !$value) {
         $this->set_value(Date::now());
     }
 }