On Thursday, 13 August 2020 at 20:11:50 UTC, Steven Schveighoffer
wrote:
On 8/13/20 4:04 PM, Andre Pany wrote:
Hi,
in the specification
https://dlang.org/spec/interfaceToC.html#storage_allocation
there is this paragraph:
"Leaving a pointer to it on the stack (as a parameter or
automatic variable), as the garbage collector will scan the
stack."
I have some trouble to understand what does this mean. Given
this example:
```
import std;
void main()
{
int* i;
sample(&i);
writeln(*i);
}
extern(C) export void sample(int** i)
{
*i = new int();
**i = 42;
}
```
Int variable is created on the heap. How do I leave a pointer
on the stack?
(In the real coding, sample function will be called from
Delphi)
The garbage collector scans all of the stack as if it were an
array of pointers. So if you have a pointer to it anywhere on
the stack, it won't be collected.
However, it only scans threads that the runtime knows about.
-Steve
If I understand it right, this paragraph doesn't help in my real
scenario where sample (Dll) is called from a delphi executable.
It is another runtime (delphi). But on the other side, as D GC
only runs if something new should be allocated on D side, I can
safely assume that the Delphi caller can access the heap
variables? Of course as long as it doesn't store the references
and use it later...
Kind regards
Andre
