C style callbacks fix for member callbacks

[IntegratedDimensions]

On Sunday, 20 May 2018 at 08:40:57 UTC, MGW wrote:
> On Saturday, 19 May 2018 at 23:52:58 UTC, IntegratedDimensions 
> wrote:
>> I have a member callback that I want to use as a C callback.
>>
>
> http://www.agner.org/optimize/calling_conventions.pdf
>
> https://www.youtube.com/watch?v=xhDS377mAc4

Sorry, I can't understand Russian(wish I could!). It also does 
not seem applicable for my problem. Although It is a useful idea 
here(using D in C++).

alias callback = extern(C) int function(const(void) a, void *b, 
uint c, void* context);

Where context acts as this.

I would like to assign a D method to this callback.

class
{
    callback c;
    /*extern(C) static*/ int foo(const(void) a, void *b, uint c, 
void* context);
    this() { c = cast(callback)&foo; }
}