[Vala] How do I call functions which have a "ref" variable as one of their argument

["Jaap A. Haitsma" <jaap haitsma org>]

Hi,

I've wanted to restart working on my vala branch of cheese. In the
meantime vala has received quite some changes. Therefore it does not
compile anymore. The main problem I have are "ref" variables. For
example with the text_extents method of Cairo

                TextExtents extents;
                text_extents ("hello", ref extents);

This does not compile because the compiler says.
"use of possibly unassigned local variable `extents' text_extents
("hello", ref extents);"

What should I do here or is it a bug in text_extents?

or also this code

                RawError dbus_error;
                
                dbus_error.init ();
                var hal = new Hal.Context ();

                if (hal == null)
                        throw new WebcamError.FAILED ("Error getting HAL context");

                if (!hal.set_dbus_connection (RawBus.get (BusType.SYSTEM, ref dbus_error)))
                        throw new WebcamError.FAILED ("Error setting dbus connection:
%s".printf (dbus_error.message));

complains about the fact that dbus_error is unassigned.

Any help will be highly appreciated

Thanks

Jaap