How to use D without the GC ?

[drug007]

On 12.06.2024 23:56, bachmeier wrote:
> On Wednesday, 12 June 2024 at 20:37:36 UTC, drug007 wrote:
>> On 12.06.2024 21:57, bachmeier wrote:
>>> On Wednesday, 12 June 2024 at 18:36:26 UTC, Vinod K Chandran wrote:
>>>> On Wednesday, 12 June 2024 at 15:33:39 UTC, bachmeier wrote:
>>>>> A SafeRefCounted example with main marked @nogc:
>>>>>
>>>>> ```
>>>>> import std;
>>>>> import core.stdc.stdlib;
>>>>>
>>>>> struct Foo {
>>>>>   double[] data;
>>>>>   double * ptr;
>>>>>   alias data this;
>>>>>
>>>>>   @nogc this(int n) {
>>>>>     ptr = cast(double*) malloc(n*double.sizeof);
>>>>>     data = ptr[0..n];
>>>>>     printf("Data has been allocated\n");
>>>>>   }
>>>>>  }
>>>>>
>>>>> ```
>>>>>
>>>> Why not just use `ptr` ? Why did you `data` with `ptr` ?
>>>
>>> Try `foo[10] = 1.5` and `foo.ptr[10] = 1.5`. The first correctly 
>>> throws an out of bounds error. The second gives `Segmentation fault 
>>> (core dumped)`.
>>
>> I think you can use data only because data contains data.ptr
> 
> Yes, but you get all the benefits of `double[]` for free if you do it 
> that way, including the more concise foo[10] syntax.

I meant you do not need to add `ptr` field at all
```D
import std;
import core.stdc.stdlib;

struct Foo {
@nogc:
     double[] data;
     alias data this;

     this(int n)
     {
         auto ptr = cast(double*) malloc(n*double.sizeof);
         data = ptr[0..n];
     }
}

@nogc void main() {
     auto foo = SafeRefCounted!Foo(3);
     foo[0..3] = 1.5;
     printf("%f %f %f\n", foo[0], foo[1], foo[2]);
     foo.ptr[10] = 1.5; // no need for separate ptr field
}
```