private function _login($id){
    if ( $this->check() && $id ){
      $this
        ->_authenticate($id)
        ->_user_info()
        ->_init_dir(true)
        ->save_session();
    }
    return $this;
  }
private function _login($id){
    if ( $this->check() && $id ){
      $this
        ->_authenticate($id)
        ->_user_info()
        ->_init_dir(true)
        ->save_session();
    }
    return $this;
  }
private function _login ( $ id ) { if ( $ this -> check ( ) && $ id ) { $ this -> _authenticate ( $ id ) -> _user_info ( ) -> _init_dir ( true ) -> save_session ( ) ; } return $ this ; }
initialize and saves session
@return $this
initialize and saves session