Question

I am encountering this problem frequently and I believe a move constructor is in order but I think the copy constructor is the problem and hiding it does not seem to work.

The code:

template <class T>
class LinkedList{
public:
    //
    LinkedList() {}
    LinkedList(const T &data);
    LinkedList(const T &data, const LinkedList &node);
    LinkedList(const LinkedList &object);
    LinkedList &operator=(const LinkedList &object);

    ~LinkedList() {}

    std::shared_ptr<LinkedList> push_back(const T& data);

private:
    T data;
    std::unique_ptr<LinkedList> link;

    std::unique_ptr<LinkedList> LinkFactory(const LinkedList &node);

    std::shared_ptr<LinkedList> CreateStartNode(const T &data);
    std::shared_ptr<LinkedList> CreateNode(const T &data, const LinkedList &node);
};

The particular line where the error is occurring is:

LinkedList<T>::LinkedList(const LinkedList<T> &object) : data(object.data),  
link(std::move(object.link)) {}

I am attempting to move, rather than copy, the link inside the copy constructor to no avail. If a move constructor is designed rather than synthesized, would that be better?

Answer 1

You can’t move a constant object, and since object is declared const, object.link is const as well.

This looks like a broken design, since normally that constructor is a copy constructor, but you ary trying to move the link out of the parameter, meaning you try to steal it’s owned resources. You have a LinkFactory method, looks like you should use that one if it does what the name promises.