C binding with D function

[bachmeier via Digitalmars-d-learn]

On Wednesday, 3 August 2016 at 15:24:56 UTC, llaine wrote:
> On Wednesday, 3 August 2016 at 15:14:24 UTC, Kagamin wrote:
>> On Wednesday, 3 August 2016 at 15:08:51 UTC, llaine wrote:
>>> So basically I have to create wrapper.c ?
>>
>> Yes, but you should write it in D. Runtime initialization is 
>> at https://dlang.org/phobos/core_runtime.html#.Runtime
>
> Okay I tried to do something like this
>
>
> import std.stdio;
> import core.runtime;
>
> extern(C)
> {
>
>   void foo(string str)
>   {
>     writeln(str);
>   }
>
> }
>
> void main(){
>   Runtime.initialize();
>   Runtime.terminate();
> }
>
> Am I doing it wrong ?
> Still getting a Segmentation fault

I have no way to test this, but translating the example to D, I 
get this:

import core.runtime;
import std.stdio;

extern(C) {
   example_init() {
     Runtime.initialize();
   }

   example_exit() {
     Runtime.terminate();
   }

   void foo(int x) {
     writeln(2*x);
   }
}

// No main
// compile as libffi-example.so

Then in Ruby:

module Example
     extend DL::Importable
     dlload "./libffi-example.so"
     extern "void example_init()"
     extern "void example_exit()"
     extern "void foo(int)"
end

Example.example_init
Example.foo(3)
Example.example_exit