Re: [Vala] Questions about structs: printing, copying, ArrayList<StructType?>

[bsquared <bwcode4u gmail com>]

On Tue, Aug 23, 2011 at 10:43 AM, Evan Nemerson <evan coeus-group com> wrote:
> On Mon, 2011-08-22 at 08:36 -0700, bsquared wrote:
> > I ran into a couple of issues regarding structs.
> >
> > 1. When using a struct from a pkg, as opposed to one of my creation,
> > an error is raised in the c code when attempting to access the
> > "built-in" to_string() method for an element.
> >
> >                   Context.State state = ctx.get_state();
> >                   print (state.to_string());
> >
> > /.../Source/vala/pulse-device-chooser/src/main.t c:160:47: error:
> > ‘PA_CONTEXT_TYPE_STATE’ undeclared (first use in this function)
>
> Looks like a missing CCode annotation in the VAPI. Depending on whether
> Context.State has a GType
>
> [CCode (type_id = "pa_context_state_get_type ()")]
>
> or
>
> [CCode (has_type_id = false)]
>
> > 2. What is the correct method to copy a struct?  Attempting to copy
> > struct by assignment to variable, or Memory.copy causes "undefined
> > reference to `pulse_audio_sink_info_copy'" errors in c code.
>
> There is no generic way to copy a struct. It depends on the library.
> There may even be no way to copy, in which case you would likely need to
> make judicious use of the "unowned" keyword.
>
> > where i & si are type PulseAudio.SinkInfo
> >
> >                 context.get_sink_info_by_index (index, (context, i, eol) => {
> >                         Memory.copy(&i, &si, sizeof(SinkInfo));
> >                         si = i;
> >                 });
> >
> >
> >
> > 3. Attempting to box struct from pkg in an ArrayList causes an error
> > in c code similar to question 1.
> > Gee.ArrayList<SinkInfo?> sink_info = new Gee.ArrayList<SinkInfo?>();
> >
> > main.c:643:31: error: ‘PULSE_AUDIO_TYPE_SINK_INFO’ undeclared (first
> > use in this function)
>
> The solution is the same as above... either specify the correct type id
> or set has_type_id = false for SinkInfo.

Thanks.  This bug was reported on freedesktop.  I added your comment there.
https://bugs.freedesktop.org/show_bug.cgi?id=40290


-- 
Regards,
-Brian