Passing myself, a struct, as a C callback context

[lobo via Digitalmars-d-learn]

On Monday, 30 March 2015 at 02:53:36 UTC, Paul O'Neil wrote:
> I'm registering a callback with some C code.  The simplified 
> story is
> here, but the actual code is on GitHub [1] at the end if you 
> care.
>
> The call looks something like this.
>
> void register(void(*fp)(void*), void* context);
>
> I have a class that holds state for the callback and registers 
> itself:
>
> final class Klass
> {
>     void method()
>     {
>         register(callback_function, &this);
>     }
> }
>
> As of dmd 2.067, doing "&this" is deprecated.  Is there an 
> idiomatic way
> to do this?
>
> [0] Actual code is at
> https://github.com/todayman/dubik/blob/master/source/vibe/core/drivers/rx.d#L177
> .  The msg object eventually gets passed to the registration 
> function.
>
> Thanks,

This is only deprecated for class not struct. This code below 
works fine:

---
import std.stdio;

extern(C) void f2(void* ins) {
     auto s = cast(S*)(ins);
     writefln("f2():%s", s);
     writefln("f2():%s", *s);
}

void f1(void* ins) {
     auto s = cast(S*)(ins);
     writefln("f1():%s", s);
     writefln("f1():%s", *s);
}

struct S { // <<-- change to "class" to get deprecated message
     int value = 10;
     void f() {
         f1(&this);
         f2(&this);
     }

}

void main()
{
     auto s = S();
     s.f();
}
---

bye,
lobo