dbus_message_new_signal parameter description

[Thiago Macieira]

On Monday, 2 de January de 2012 18.08.13, Bogdan Lotko wrote:
> Thanks for the answer,
> 
> Please see my comment below
> 
> On 1/2/2012 17:15, Mike Gorse wrote:
> > Signals are broadcasts and don't specify a destination--when you send
> > a signal, you aren't concerned with the foreign objects that are
> > listening for it.
> 
> Yes, I know this. Exactly this is the reason why I think that the signal
> is emitted  "for"  foreign (listening) objects that expose according
> interface and not "from" an interface.

That's not correct. The interface of the signal is a property of the sender, 
not of the receiver. In fact, the receiver doesn't even have to have an object 
associated, so no interfaces actually exist.

> As I already wrote, my object that emits (broadcasts) signals also
> exposes its own interface (nothing to do with signals sent), so the
> phrase  "the interface the signal is emitted from" is somehow misleading
> for me.

Please rethink, because it's quite important.

If a signal is emitted from object $OBJECT_PATH with interface $IFACE and name 
$MEMBER, then if you were to introspect $OBJECT_PATH, you should find $IFACE 
and the member $MEMBER inside as a signal. That is:

    <interface name="$IFACE">
        <signal name="$MEMBER">
            <!-- parameters, if any -->
        </signal>
    </interface>

So the interface is the interface the signal is emitted *from*.
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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