On 07/24/2019 05:35 PM, Ben Ogles wrote:
> Is there a way to use a C header that contains a struct declaration but
> no definition?
>
> For example, the C header may contain:
>
> typedef struct some_type_s some_type;
>
> Which is only fully defined in the implementing C file:
>
> struct some_type_s { ... };
And that type is traded as pointer to some_type on the C API, right?
Usually there is a factory method that returns a pointer to a
dynamically allocated object.
> I am trying to wrap the header in D:
>
> extern(C)
> {
> struct some_type_s;
> alias some_type = some_type_s;
> }
>
> And then use it in another D file:
>
> some_type s;
>
> But dmd does not know the size of the struct so it can't compile. Is
> there a work around to this other than moving the struct definition into
> the C header file?
Indeed. The only option is to use some_type* on the D API as well:
extern(C) {
struct S;
S* C_API_allocate();
void C_API(const(S) *);
}
// D API
void foo(S* s) {
C_API(s);
}
void main() {
auto s = C_API_allocate();
foo(s);
}
Note: That program fails to link because C API functions are missing
definitions.
You can wrap the pointer i a D struct and dispatch member function calls
to the C API.
Ali
