def get_pspec name
      pspec = GObject::GParamSpecPtr.new
      argument_class = Vips::ArgumentClassPtr.new
      argument_instance = Vips::ArgumentInstancePtr.new

      result = Vips::vips_object_get_argument self, name,
          pspec, argument_class, argument_instance
      return nil if result != 0

      pspec
    end
def get_pspec name
      pspec = GObject::GParamSpecPtr.new
      argument_class = Vips::ArgumentClassPtr.new
      argument_instance = Vips::ArgumentInstancePtr.new

      result = Vips::vips_object_get_argument self, name,
          pspec, argument_class, argument_instance
      return nil if result != 0

      pspec
    end
return a pspec, or nil ... nil wil leave a message in the error log
 which you must clear