Planned incompatible change in `dbus-send-signal'

[Michael Albinus]

Hi,

I'm preparing changes in dbus.el for inclusion in Emacs 24.2. One change
would be to support unicast signals as introduced in D-Bus 1.5, see
<http://dbus.freedesktop.org/doc/dbus-specification.html#message-bus-routing>.

As a consequence, the semantics of the `dbus-send-signal' argument
SERVICE would change. Until now, it is specified merely for orthogonal
reasons, and shall describe the D-Bus service name the signal is sent
from. All signals are broadcast signals.

After my intended change, a SERVICE value `nil' would mean a broadcast
signal, and a string value would mean the target service of a unicast
signal. That's an incompatible change.

Would it be OK to change it this way? I've searched over the net, and
I've found just one instance where `dbus-send-signal' is used (in
pida_emacs_dbus.el, see <http://pida.co.uk/browser/pida/resources/data>).
Would it be necessary to add a compatibility flag somewhere in dbus.el,
and (if yes) how?

Best regards, Michael.