On Monday, 17 April 2023 at 18:34:19 UTC, DLearner wrote:
Requirement is to write some D code (which avoids the GC), that
will be called from C.
So simple approach seemed to be to write D code under -betterC
restrictions.
However, also need variable length arrays - but D Dynamic
Arrays not allowed under -betterC.
[...]
Any ideas how to implement variable length arrays under
-betterC?
You need a struct with operator overloads and libc realloc(),
(very) basically
```d
struct Array(T)
{
private:
struct Payload
{
T* ptr;
size_t length;
}
Payload p;
public:
size_t length() {
return p.length;
}
void length(size_t v) {
import core.stdc.stdlib;
p.ptr = cast(T*) realloc(p.ptr, v * T.sizeof);
}
ref T opIndex(size_t i) {
return p.ptr[i];
}
}
void main()
{
Array!int a;
}
```
but you'll have to implement
- ctors
- concat assign
- slice assign
- copy construction
- value type elem alignment
- default elem construction
- default elem destruction
- etc.
to make that usable in on trivial cases.
Maybe try to find an already existing one;
https://github.com/gilzoide/betterclist
https://github.com/aferust/dvector
(maybe more in https://code.dlang.org/search?q=betterc)
