function parent($new = null, $return_entity = false)
    {
        if (isset($new)){
            if ($new instanceof Entity){
                $this->_parent = $new;
                $new = $new->uri();
            }else{
                $this->_parent = null; // for reloading
            }
            if ($new != $this->_attributes['parent']){
                $this->change('parent', $new);
                $this->change('order', Entity::MAX_ORDER);
                $this->change('uri', $new.'/'.$this->_attributes['name']);
            }
        }
        if ($return_entity){
            if (!isset($this->_parent)){
                if (isset($this->_attributes['parent'])){
                    $this->_parent = Data::read($this->_attributes['parent']);
                }else{
                    $this->_parent = false;
                }
            }
            return $this->_parent;
        }
        return $this->_attributes['parent'];
    }