Dynamic UrlMapping using request parameters

Might be old news to some, but I just found you can assign closures to the action and controller values in URL mappings, e.g.

"/update/$controller/$target" {
   action = {
      "update" + params.target[0].toUpperCase() + params.target.substring(1);
   }
}

Great for mapping restful style urls to meaningful action names, e.g.

"/update/patient/speciality" => PatientController.updateSpeciality