[Vala] new async gio vapi

[lariamat <interflug1 gmx net>]

Hi all
I wonder how the latest changes to the gio vapi have to be used in a
program. I have no experience with the other async stuff. How can I
connect that to a callback that would handle the GLib.AsyncResult like
in
http://live.gnome.org/Vala/GIOSamples#head-164983820b65aa689b970b193fec6ddc7368179e
? 

Excerpt from the patch: 
- public void read_line_async (int io_priority, GLib.Cancellable?
cancellable, GLib.AsyncReadyCallback callback);
- public unowned string read_line_finish (GLib.AsyncResult _result, out
size_t length) throws GLib.Error;
+ public async unowned string read_line_async (int io_priority,
GLib.Cancellable? cancellable, out size_t length) throws GLib.Error;
+ public unowned string read_line_finish (GLib.AsyncResult _result, out
unowned size_t length) throws GLib.Error;

Thanks for any help!
Regards