Re: Why doesn't dbus-handle-event catch all errors?

[Michael Albinus <michael.albinus@gmx.de>]

Daniel Colascione <dancol@dancol.org> writes:

>> You're free to write a handler which returns any error as dbus error, if
>> your program logic requires this.
>
> The only reasonable implementation of a dbus handler is one that
> transforms lisp errors to dbus errors, so why not do that
> automatically in dbus.el? Silently swallowing lisp errors is the less
> common case, and if a program needs to do that, it can wrap its logic
> in ignore-errors inside the handler.

There is the special error type `dbus-error'. Any handler could catch
lisp errors and transform them into something which is understandable to
another process. You do not want to send "(wrong-type-argument listp
42)" or something like this to another process, which isn't aware of Lisp.

Your handler shall include something like

(defun my-dbus-method-handler (&rest args)
  (condition-case err
      (...)
    (error (signal 'dbus-error (list "Something went wrong, please try it again")))))

Best regards, Michael.