function set_conf( $confname ){
		$this->confname = $confname;
		$this->confdir = PLUG_HOST_DIR.'/'.$confname;
		if( ! PLUGTool::check_dir($this->confdir) ){
			throw new PLUGException('bad conf');
		}
		// parse default plug conf using external parser
		$confpath = $this->confdir.'/PLUG.conf.php';
		$this->conf_vars = array();
		$this->conf_consts = array ();
		$this->load_conf( $confpath );
	}