D Bindings for C Opaque Pointers

[Kyle Ingraham]

On Thursday, 3 December 2020 at 00:58:20 UTC, Paul Backus wrote:
> On Thursday, 3 December 2020 at 00:30:06 UTC, Kyle Ingraham 
> wrote:
>>
>> // EDSDKTypes.h
>> typedef struct __EdsObject* EdsBaseRef;
>> typedef EdsBaseRef EdsCameraListRef;
>> //
>>
> [...]
>>
>> // edsdk.d
>> struct EdsBaseRef;
>> alias EdsBaseRef EdsCameraListRef;
>
> You've dropped a level of indirection here. In the C header, 
> EdsBaseRef is a pointer, but in your D code, it is an opaque 
> struct.
>
> The correct way to translate these C declarations into D is:
>
> struct __EdsObject;
> alias EdsBaseRef = __EdsObject*;
> alias EdsCameraListRef = EdsBaseRef;
>
> Note that unlike C, D does not allow us to refer to an 
> incomplete type without first declaring it.

That did it. The binding works without issue now. Thanks a ton 
for the direction.

I'll keep that distinction between C and D in mind as I go 
forward.

It's been night and day between D and C++. I struggled for a 
while getting this work going in C++ but was firmly blocked by 
CMake. D and dub have been champs for ease of use.