Re: [Vala] Generating bindings for non-GLib/GObject based API

[Jan Hudec <bulb ucw cz>]

On Sun, Apr 25, 2010 at 11:46:17 +0200, Michael Wild wrote:
> On 23. Apr, 2010, at 22:29 , Jan Hudec wrote:
> > Actually I believe
> >
> >    [Compact]
> >    [CCode (cname = "void", ...)]
> >    class Thing ...
> >
> > should work. It will give you void * passed around, so it's some kind of
> > pointer and C implicitly casts to and from void *, so no errors and no
> > warnings.
>
> I don't think that I'd like that one particularly... I'd rather prefer to
> use a Vala wrapper class then.
>
> > You can also just make it
> >
> >    [Compact]
> >    [CCode (cname = "struct unknown_type", ...)]
> >    class Thing ...
> >
> > with the real value for "unknown_type" from the library header. That will
> > make the code more type-safe on the C side, but vala will check the types
> > enough and it would be relying on something not officially documented.
>
> Unfortunately that's impossible. The official standard states that there is
> a opaque type Thing, but nothing more. Every implementor is free to do as
> he pleases... Some even typedef it to an integer handle.

The void case would be OK if you knew it is always a pointer. But if it's
a handle of any type, than you'll have to make it a "[SimpleType] struct"
(SimpleType means it's passed by value).

Than you can try whether setting a copy_function and destroy_function on
a simple type will do what you need and otherwise you'll just have to wrap
it in a normal vala object.

-- 
                                                 Jan 'Bulb' Hudec <bulb ucw cz>