[pulseaudio-discuss] [Vala] Issues will vala and pulse vapi

Al Thomas astavale at yahoo.co.uk
Sun Nov 22 16:56:00 PST 2015

> From: Evan Nemerson <evan at coeus-group.com>

> Sent: Sunday, 22 November 2015, 3:54
> Subject: Re: [Vala] Issues will vala and pulse vapi
> On Sat, 2015-11-21 at 20:48 -0600, Aaron Paden wrote:
>>  Right, the code compiles, but the linker fails because of the
>>  unresolved symbols. I didn't think of this before, but the minimal
>>  example is pretty simple:
>>  void main() {
>>    PulseAudio.SourceInfo info;
>>  }
> If you don't provide a destroy_function CCode annotation but Vala
> determines that it is necessary to call one, it will default to
> lower_case_cprefix_destroy, which is why it is generating a call to
> pulse_audio_source_info_destroy.

Hmm, just found this in the Legacy Bindings documentation (
https://wiki.gnome.org/Projects/Vala/LegacyBindings#Structs ):

"It's important to note that if a struct doesn't have a destroy function specified, Vala will generate one given there are any fields in the struct which look like they need to be deallocated, which may or may not behave correctly depending on the context. An empty destroy_function will keep the generated code correct and prevent Vala from generating a destructor."

So in the VAPI try:
[CCode (cname="pa_sink_info", destroy_function = "", has_type_id=false)]
public struct SinkInfo {

If that works then I think we can say the Legacy Bindings
document has some real nuggets in there, it just needs a bit more
re-organisation to make this information more easily found.
At the moment this information is under recognizing Vala
semantics in C code and not the details of memory management.


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