On Fri, Apr 23, 2010 at 09:36:18 +0200, Michael Wild wrote:
> Another thing where I'm not sure how to best solve it: The basic C-type I'm
> using is a typedef to a pointer whose base-type is implementation dependent
> (i.e. unknown). E.g. like this:
>
> typedef struct unknown_type* Thing;
>
> Now, in my small test cases, I used the following for the binding:
>
> [SimpleType]
> [CCode (cname = "Thing", cheader_filename = "thing.h", free_function =
> "free")]
> struct Thing {
> [CCode (cname = "create_thing")]
> private static int create_imp(Thing* self, int a, int b, double c);
> [CCode (cname = "create_thing_wrapper")]
> public static Thing create(int a, int b, double c) {
> Thing self;
> int stat = create_imp(&self, a, b, c);
> return self;
> }
>
> [CCode (cname = "print_thing")]
> public void print();
> }
>
> This compiles and runs, but Vala now (quite understandably) thinks that
> Thing is a value-type and doesn't call free() on it. AFAIK for this to
> happen I'd need to change Thing to be a of compact class type, but then
> everything else would break because Vala starts passing the object around
> as a pointer (i.e. resulting in unknonw_type**, where unknown_type* is
> expected).
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.
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.
You may also need to set the [CCode(copy_function=...)] or explicitly tell
vala that it can't be copied via [CCode(has_copy_function=false)].
On a side note, structs normally have destroy_function rather than
free_function, but I am not sure there is a difference.
--
Jan 'Bulb' Hudec <[email protected]>
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