Re: [Vala] How to properly define struct in manually written VAPI?

[Ben <iofelben gmail com>]

FYI, Vala already has binding for json-glib 
http://valadoc.org/#!api=json-glib-1.0/Json
It has nice features like deserialization with GObject properties

On Wed, Mar 2, 2016 at 5:19 AM, marcin saepia net <marcin saepia net> 
wrote:
> Hello,
>
> I need to write VAPI for jansson JSON library. I have already started 
> (
> https://github.com/akheron/jansson/pull/273) and generally speaking it
> works fine but I have an issue with covering one struct.
>
> In C code there's the following struct:
>
>
> #define JSON_ERROR_TEXT_LENGTH    160
> #define JSON_ERROR_SOURCE_LENGTH   80
>
> typedef struct {
>     int line;
>     int column;
>     int position;
>     char source[JSON_ERROR_SOURCE_LENGTH];
>     char text[JSON_ERROR_TEXT_LENGTH];
> } json_error_t;
>
>
> it is an output parameter to function that should have the following 
> syntax
> in Vala:
>
> loads(string input, LoadFlags flags, out Error error)
>
> I struggle to properly define it in VAPI. When I define it like this:
>
>   [CCode (cname = "json_error_t",  has_type_id = false)]
>   public struct Error {
>     public string text;
>     public string source;
>     public int line;
>     public int column;
>     public size_t position;
>   }
>
> it complains about missing copy function during C compilation phase
>
> when I add
>
>   [CCode (cname = "json_error_t", has_copy_function = false, 
> has_type_id =
> false)]
>   public struct Error {
>     public string text;
>     public string source;
>     public int line;
>     public int column;
>     public size_t position;
>   }
>
> it then throws
>
> api/auth/oauth2.c:939:2: error: array type 'char [160]' is not 
> assignable
>         _g_free0 ((*dest).text);
>         ^         ~~~~~~~~~~~~
> api/auth/oauth2.c:51:28: note: expanded from macro '_g_free0'
> api/auth/oauth2.c:940:15: error: array type 'char [160]' is not 
> assignable
>         (*dest).text = _tmp1_;
>         ~~~~~~~~~~~~ ^
> api/auth/oauth2.c:943:2: error: array type 'char [80]' is not 
> assignable
>         _g_free0 ((*dest).source);
>         ^         ~~~~~~~~~~~~~~
>
>
> How to define it properly? Underlying API does not provide any 
> destroy/copy
> functions.
>
> I also tried to convert it to the compact class but then Vala Compiler
> creates pointer-to-pointer for underlying C code for the parameter 
> which is
> improper.
>
> Thanks,
>
> Marcin
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