On Tuesday, 29 October 2013 at 12:03:09 UTC, Rene Zwanenburg
wrote:
On Monday, 28 October 2013 at 19:40:26 UTC, Maxim Fomin wrote:
The fact that structs are movable and there is too few struct
runtime reflection makes them noncollectable. However, you can
wrap struct inside class, in such case struct dtor will be
called.
Yeah, if wrapping inside a class wouldn't work either we'd be
in a whole new world of hurt.
But what do you exactly mean by noncollectable? And what does
movability have to do with that? I think the memory will be
reclaimed without a problem, so new-ing a struct without
destructor would be fine. This doesn't leak:
struct S
{
int i;
}
void main()
{
while(true)
{
new S;
}
}
I would say it leaks because dtor (if defined) is not called,
although memory is reclaimed at some point. In my opinion struct
movability is a problem for heap struct collection because it is
hard to say judging to struct stack/heap pointer whether it
should be collected or not. If you look at output from previous
example,
ctor, 1
dtor, 7FFFF7ED8FF8, 1
ctor, 2
dtor, 7FFFFFFFDB30, 1
you will see that adressess are different and refer to stack, yet
object is in the heap. By the way, there is another issue - if
you have delegate inside struct method touching some field, than
invoking such delegate after returning from method may break
memory, because delegate references 'this' struct pointer, but it
may be changed across lifetime. I am not sure whether some
algorithm for solving heap struct collectibility can be made, but
I don't have any idea right now.
