Re: [Vala] Need help to make binding for typedef'd pointer struct

[Jonas Kulla <nyocurio gmail com>]

2012/10/3 Ahmad Syukri bin Abdollah <syockit gmail com>

> Greetings!
>
> Not long ago, someone made a binding for GMP
> (https://mail.gnome.org/archives/vala-list/2011-August/msg00048.html)
> and posted it on the wiki, but it seems to have been lost.
> I'm attempting to write a new one, but came across some design
> difficulties.
>
> In the original API, the custom number types are structs. To use them,
> they are allocated, initialized, and passed to API functions via its
> pointer.
>
>   {snip: C example}
>   /* declare var using mpz_t, which is typedef'd to the length-1 array
> of the struct */
>   mpz_t num1, num2;
>   /* initialize */
>   mpz_init_set_ui(num1, 1495);
>   mpz_init_set_si(num2, -30);
>   /* do operations */
>   mpz_add(num2, num1, num2);
>
> I managed to conjure a simple binding using struct to interface the
> original struct, since you can't typedef a pointer struct in Vala.
> But then the usage will look like this:
>
> {snip: Vala exampe}
> mpz_t num1, num2;
> mpz.init_set_ui(out num1, 1495);
> mpz.init_set_ui(out num2, 1495);
> mpz_add(&num2, &num1, &num2);
> // or maybe: mpz_add(out num2, out num1, out num2);
>
> If possible I'd like to avoid having to use ref/out/&. A compact class
> seems to be a good substitute, since they are passed by reference by
> default.
> The problem is, class needs a "new" function, which doesn't exist in
> the API (because the types designed as objects).
> Can I define what the new function does without having to include an
> extra header file?
>
> Regards,
> A. Syukri

Hi!

I think I had a similar problem to yours when writing a vapi for the
popular minizip utilities.
What they did was typedef a void pointer to an opaque type, which was
passed by value,
and it seems to me from the C code you provided that it's the same case
here as well(?).
Anyway, what I did was simply declare the type as a [SimpleType] struct (no
pun intended).
This solution isn't perfect, but it worked for me.

 - Jonas