Re: [Vala] calling delegate from async

[pHilipp Zabel <philipp zabel gmail com>]

On Sat, Oct 24, 2009 at 4:44 PM, pHilipp Zabel <philipp zabel gmail com> wrote:
> On Sat, Oct 24, 2009 at 12:59 PM, Jan Hudec <bulb ucw cz> wrote:
> > On Fri, Oct 23, 2009 at 15:31:53 +0200, pHilipp Zabel wrote:
> > > Hi,
> > >
> > > I'd like to call a delegate function from an async function, like this:
> > >
> > > class AsyncDelegate {
> > >         delegate void TestFunc ();
> > >
> > >         void test_func () {
> > >                 print ("delegate\n");
> > >         }
> > >
> > >         async void test_async (TestFunc f) {
> >
> > Can you try it with
> >
> >    async void test_async (owned TestFunc f) {
> >
> > ?
>
> Thanks, but that doesn't work either.
> I filed a bug, details at https://bugzilla.gnome.org/show_bug.cgi?id=599487
>
> The first problem is that the AsyncDelegateTestFunc delegate typedef
> in the generated code appears only after the struct
> _AsyncDelegateTestAsyncData, in which it is referenced.
>
> The second problem is that the struct _AsyncDelegateTestAsyncData is
> missing a GDestroyNotify f_target_destroy_notify member, even after I
> add the owned keyword as you suggest.

With Jürg's help I came up with a patch
(http://bugzilla-attachments.gnome.org/attachment.cgi?id=146187) that
fixes both problems.

I still get the critical error message, though:

** (valac:1106): CRITICAL **: vala_data_type_get_value_owned: assertion `self
!= NULL' failed

Any idea where this is coming from?

> > >                 print ("async enter\n");
> > >                 Idle.add (test_async.callback);
> > >                 yield;
> > >                 f ();
> > >                 print ("async leave\n");
> > >         }
> > >
> > >         static int main (string[] args) {
> > >                 var loop = new GLib.MainLoop (null, false);
> > >                 var app = new AsyncDelegate ();
> > >
> > >                 app.test_async.begin (app.test_func);
> > >                 print ("loop\n");
> > >                 loop.run ();
> > >
> > >                 return 0;
> > >         }
> > > }
> > >
> > > But Vala 0.7.7 doesn't like that at all:
> > >
> > > ** (valac:7627): CRITICAL **: vala_data_type_get_value_owned:
> > > assertion `self != NULL' failed
> > > /home/ph5/vala/async-delegate/async-delegate.vala.c:44: error:
> > > expected specifier-qualifier-list before Б─≤AsyncDelegateTestFuncБ─≥
> > > [...]
> > > Compilation failed: 1 error(s), 0 warning(s)
> >
> > It can't work with unowned delegate (add 'owned' as mentioned above), because
> > vala can't guarantee the invocant will be valid by the time the async
> > function gets to call it.
> >
> > However, vala should report an understandable error, so filing a bug would be
> > appropriate.
>
> I see. I filed a second bug for the error messages:
> https://bugzilla.gnome.org/show_bug.cgi?id=599488

And for this one I've got a patch proposal, too:
http://bugzilla-attachments.gnome.org/attachment.cgi?id=146188

regards
Philipp