How do you get shared_ptr weak count?

Question

Is it possible to get the weak reference count to a shared_ptr? I know how I can get the shared_ptr use count using

std::shared_ptr::use_count

but I would like to know if there are any non-implementation specific ways to get the number of weak_count references?

There's none. At most, there might be a way many implementations happen to support. — Deduplicator, Aug 07 '14 at 16:19
What is the real problem you're trying to solve? (And also note the standard puts no performance constraints on `use_count` either `[20.7.2.2.5/8]`). — Mark B, Aug 07 '14 at 16:38
@MarkB: I am interested in this too; since there is no way to prevent someone else to create another reference concurrently... — Matthieu M., Aug 07 '14 at 16:42
Even if you could get to the weak reference count, it's unlikely to be useful because the value is implementation dependent. A library may choose to implement it as `weak_count = num_weak_refs + (use_count > 0)` or `weak_count = num_weak_refs + use_count` — Praetorian, Aug 07 '14 at 16:43

score 2 · Accepted Answer · answered Aug 07 '14 at 16:22

2

Not in C++11, and not in this draft of C++14.

answered Aug 07 '14 at 16:22

Mike Seymour

score -1 · Answer 2 · answered Aug 08 '14 at 15:17

-1

No, remember that weak_ptrs are just observers rather than an actual pointer to the object they are not designed to return their counts.

answered Aug 08 '14 at 15:17

2 Answers2