function &_addAttachmentPart(&$obj, $value)
    {
        $params['eol']          = $this->_build_params['eol'];
        $params['filename']     = $value['name'];
        $params['encoding']     = $value['encoding'];
        $params['content_type'] = $value['c_type'];
        $params['body_file']    = $value['body_file'];
        $params['disposition']  = isset($value['disposition']) ? 
                                  $value['disposition'] : 'attachment';

        // content charset
        if (!empty($value['charset'])) {
            $params['charset'] = $value['charset'];
        }
        // headers charset (filename, description)
        if (!empty($value['headers_charset'])) {
            $params['headers_charset'] = $value['headers_charset'];
        }
        if (!empty($value['language'])) {
            $params['language'] = $value['language'];
        }
        if (!empty($value['location'])) {
            $params['location'] = $value['location'];
        }
        if (!empty($value['name_encoding'])) {
            $params['name_encoding'] = $value['name_encoding'];
        }
        if (!empty($value['filename_encoding'])) {
            $params['filename_encoding'] = $value['filename_encoding'];
        }
        if (!empty($value['description'])) {
            $params['description'] = $value['description'];
        }
        if (is_array($value['add_headers'])) {
            $params['headers'] = $value['add_headers'];
        }

        $ret = $obj->addSubpart($value['body'], $params);
        return $ret;
    }