Re: [Vala] Crazy Vala callback behavior

[Abderrahim Kitouni <a kitouni gmail com>]

Hello

                 في ح، 18-12-2011 عند 00:32 +0100 ، كتب Matthias Klumpp:
> Hi!
> This is a bit difficult to reproduce, so I'm not sure if this really is a bug.
> I am mixing Vala and C code. I implement an internal class in Vala,
> which defines the following callback:
>   public signal Results request_whatprovides (uint filters, uint
> provides, [CCode (array_length = false, array_null_terminated = true)]
> string[] search);

AFAIK, signals with return values aren't supported in Vala. Another
important thing you didn't mention is what is result (is it a class, a
struct). And since you're talking about a callback, maybe you meant
delegate instead of signal. Please explain what you want to do rather
than how you think you should do it, it's better for helping you.

> This callback is used to forward requests to a C library, which is
> itself loaded as GModule, but I don't think this matter. Anyway, I
> would expect that I need to implement a callback in C using these
> parameters:

I think you really mean a delegate, and if so, your callback should have
the arguments (guint filters, guint provides, gchar** search, gpointer
user_data), and return a Results* if Results is a reference type, and
have the arguments (guint filters, guint provides, gchar** search,
Results* result, gpointer user_data) if Results is a struct.

>  xy_request_whatprovides_cb (BackendProxy *sender,
>                               PkBitfield filters,
>                               PkProvidesEnum provides,
>                               gchar** search,
>                               gpointer user_data)

Why are you using different types for the arguments? You should probably
have bindings for the library that is used by both you app and the
loadable module.

HTH,
Abderrahim