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shared_ptr is a reference counting smart pointer in the Boost library.
The problem with reference counting is that it cannot dispose of cycles. I am wondering how one would go about solving this in C++.
Please no suggestions like: "don't make cycles", or "use a weak_ptr".
Edit
I don't like suggestions that say to just use a weak_ptr because obviously if you know you will create a cycle, then you wouldn't have a problem. You also cannot know you will have a cycle in compile time if you generate shared_ptrs during runtime.
So please, self delete answers that use weak_ptr in them because I specifically asked not to have those kind of answers...
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In short: Use unique_ptr when you want a single pointer to an object that will be reclaimed when that single pointer is destroyed. Use shared_ptr when you want multiple pointers to the same resource.
So, we should use shared_ptr when we want to assign one raw pointer to multiple owners. // referring to the same managed object. When to use shared_ptr? Use shared_ptr if you want to share ownership of a resource.
The smart pointer has an internal counter which is decreased each time that a std::shared_ptr , pointing to the same resource, goes out of scope – this technique is called reference counting. When the last shared pointer is destroyed, the counter goes to zero, and the memory is deallocated.
The shared reference counter counts the number of owners. Copying a std::shared_ptr increases the reference count by one. Destroying a std::shared_ptr decreases the reference count by one. If the reference count becomes zero, the resource will automatically be released.
shared_ptr represents ownership relation. While weak_ptr represents awareness. Having several objects owning each other means you have problems with architecture, which is solved by changing one or more own's into aware of's (that is, weak_ptr's).
I don't get why suggesting weak_ptr is considered useless.
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