Hi !
http://dpaste.dzfl.pl/53d9a59e

How i can enforce that ~A will be called after ~B ?

I'm writing 3D engine and it's critical to me.

Thanks for yours aid !

Please, don't advise to call b.destroy.

Temtaime:

> How i can enforce that ~A will be called after ~B ?
> I'm writing 3D engine and it's critical to me.

The GC doesn't give such guarantees. So you need something manual, or to use RAII, or scope(exit), or some other idea like creating an array of objects to be destroyed, etc.

Bye,
bearophile

In this specific case, you can force a collection at the end of main()


void main() {
	auto b = new B;
	a = new A;

	import core.memory;
	GC.collect();
}

The gc runs automatically at the end of the program, but at that point, both b and a are gone, so the gc just gets to it as soon as it can. Manually calling collect after you're done with b but before the program ends (so a is still in use) it should do it in order.

But, generally, if you want to rely on destructors at all, you have to use structs, or at least destroy(). They might never run with classes and the order is undefined - it all depends on when and if the GC ever actually grabs it.

Thought a struct at module scope might never run its destructor at all...

On 11/29/2013 08:58 AM, Adam D. Ruppe wrote:

> In this specific case, you can force a collection at the end of main()
>
>
> void main() {
>      auto b = new B;
>      a = new A;
>
>      import core.memory;
>      GC.collect();
> }

Note that the OP requires the unusualy destruction order: b first.

In any case, these objects can be destroyed without destroy anyway.

    mixin("dest" ~ /* :p */ "roy(a);");

Ali

On Friday, 29 November 2013 at 16:48:58 UTC, Temtaime wrote:
> Hi !
> http://dpaste.dzfl.pl/53d9a59e
>
> How i can enforce that ~A will be called after ~B ?
>
> I'm writing 3D engine and it's critical to me.
>
> Thanks for yours aid !

It is impossible to do this directly given current gc implementation, but you can do something like that:

class A
{
   bool reset;
   void delegate dtor();
   ~this()
   {
      if (!reset)
         dtor();
   }
}

class B
{
   A a;
   bool run;
   ~this() { if (!run) a.reset = true; run = true; }
}

A a = new A;
B b = new B;
b.a = a;
b.a.dtor = & b.__dtor;

I see.
Thanks for all for yours replies !

> class A
> {
>    bool reset;
>    void delegate dtor();
>    ~this()
>    {
>       if (!reset)
>          dtor();
>    }
> }
>
> class B
> {
>    A a;
>    bool run;
>    ~this() { if (!run) a.reset = true; run = true; }
> }
>
> A a = new A;
> B b = new B;
> b.a = a;
> b.a.dtor = & b.__dtor;

relying on to "bool reset" it's no good idea.

In this case a manual memory management - good choice.