Use weak pointers with shared objects
Strictly speaking, std::weak_ptr is not a smart pointer. Rather, it's an observer that operates in cooperation with shared_ptr. A weak_ptr object does not hold a pointer on its own.
There are circumstances where shared_ptr objects may create dangling pointers or race conditions, which could lead to memory leaks or other problems. The solution is to use weak_ptr objects with shared_ptr.
How to do it…
In this recipe, we examine the use of std::weak_ptr with std::shared_ptr, using a demonstration class that prints when its constructors and destructor are called.
- We start with the same class we've used to demonstrate
shared_ptrandunique_ptr:struct Thing { Â Â Â Â string_view thname{ "unk" }; Â Â Â Â Thing() { Â Â Â Â Â Â Â Â cout << format("default ctor: {}\n", thname); Â Â Â Â } Â Â Â Â Thing...
