How to check if sender of message still exists?

[Ryan Lortie]

hi,

Just a few more clarifications on what Simon said.

On Thu, 2011-06-09 at 11:41 +0100, Simon McVittie wrote: 
> If you're listening for the NameOwnerChanged signal you will see the ownership
> of the plugin's unique name change from itself to the empty string:
> 
>     NameOwnerChanged(":1.407", ":1.407", "")

It's best to do this using the 'arg0' signal matching parameter.  This
prevents you from receiving *all* NameOwnerChanged signals needlessly.

Also, be sure to verify that the name actually exists *after* you
subscribe to the NameOwnerChanged signal.  You can do this with the
NameHasOwner call.  If you don't do this, it's possible to subject
yourself to a race whereby the client exits immediately after sending a
message and you subscribe to NameOwnerChanged after it is already gone.

> See the D-Bus Specification for more about NameOwnerChanged, or (for instance)
> tp_dbus_daemon_watch_name_owner() in telepathy-glib for example.code.

In GDBus, g_bus_watch_name().

In general, you are advised to attempt to use one of these high-level
facilities as provided by a D-Bus client library instead of rolling your
own.  It's very easy to make a couple of common mistakes when
implementing this pattern, and the authors of these libraries have spent
more time understanding the problem than you probably care to.

Cheers