cppWeak_ptrExample

#include <iostream>
#include <memory>

class Item
{
    std::string name;
    std::weak_ptr<Item> pair;
public:
    const int size{ 34 };
    Item(std::string nameP) : name{ nameP } { std::cout << "Item created for " << this << '\n'; }

    Item(const Item& it) = delete;
    Item& operator=(const Item& it) = delete;


    const std::string& getName()const { return name; };

    void print()const { std::cout << "Item # " << this << " named " << name << '\n'; }
    ~Item() { std::cout << "Item destroyed for " << this << '\n'; }

    const std::shared_ptr<Item> getPair()const { return pair.lock(); }

    friend bool addPair(std::shared_ptr<Item>& left, std::shared_ptr<Item>& right)
    {
        if (!left or !right)
        {
            return false;
        }

        left->pair = right;
        right->pair = left;

        std::cout << left->getName() << " paired with " << right->getName() << '\n';

        return true;
    }

    friend bool addFriend(std::shared_ptr<Item>& left, std::shared_ptr<Item>& right)
    {
        if (!left or !right)
        {
            return false;
        }

        left->pair = right;

        std::cout << right->getName() << " is friend of " << left->getName() << '\n';

        return true;
    }
};

void printItem(Item* it)
{
    it->print();
}


int main()
{
    std::shared_ptr<Item> it1{ std::make_shared<Item>("Item One") };//[One - 1]
    std::shared_ptr<Item> it2{ std::make_shared<Item>("Item Two") };//[Two - 1]

    addPair(it1, it2); // [One - 1] [Two - 1]
    //addFriend(it1, it2);

    std::cout << std::boolalpha << "One paired with Two: " << (it1 == it2->getPair()) << '\n'; // [One - 2] [Two - 1] -> [One - 1] [Two - 1]
    std::cout << std::boolalpha << "Two paired with One: " << (it2 == it1->getPair()) << '\n'; // [One - 1] [Two - 2] -> [One - 1] [Two - 1]

    auto it1Pair{ it1->getPair() }; //[Two - 2]
    auto it2Pair{ it2->getPair() }; //[One - 2]

    std::cout << "Item One pair is: " << it1Pair->getName() << '\n';
    std::cout << "Item two pair is: " << it2Pair->getName() << '\n';

    //it1->print();
    //it2->print();


    return 0;
}
// it2Pair - [One - 1]
// it1Pair - [Two - 1]
// it2 [Two - 0 x]
// it1 [One - 0 x]