protected function databind ()
  {
    if (isset($this->bindings))
      foreach ($this->bindings as $attrName => $bindExp) {
        $value = $this->evalBinding ($bindExp);
        if (is_object ($value))
          $this->props->$attrName = $value;
        else $this->props->set ($attrName, $value);
      }
  }