How to refer to different sized static arrays

[Ali Çehreli]

On 2/8/20 12:22 AM, Adnan wrote:
> Just a foreword, this is for learning purposes, hence I am not using the 
> dynamic array or Array!T.
> 
> I have a structure that maintains a heap allocated sized array inside.
> 
> struct LifoStack(T) {
>    T[?] data;
> }
> 
> This `data` is manually resized and copied. Thus the size itself is not 
> a compile time constant. What should go inside `?` in the the type 
> signature of data?

You just leave the parentheses empty:

   T[] data;

T[] is internally two things, the equivalent of the following:

    size_t length;
    T * ptr;

> Also, how can I create runtime-determined sized fixed array in the heap?

To have fixed-size array, you have to somehow spell the size out at 
compile time. The closest thing that comes to mind... does not make 
sense... :)

T[N] makeStaticArray(T, size_t N)() {
   T[N] result;
   return result;
}

void main() {
   auto arr = makeStaticArray!(int, 42)(); // <-- Must say 42
}

See std.array.staticArray, which is much more useful:

   https://dlang.org/phobos/std_array.html#staticArray

But, really, if the size is known at run time, it's a dynamic array. :)

Ali