QMap and std::unique_ptr

Question

I am trying to prevent naked pointers, to prevent memory leaking etc. I also want to map int to INuiSensor*. Since I am also using Qt I tried to use QMap<int, std::unique_ptr<INuiSensor>> to do this, but the source code of QMap makes this impossible:

template <class Key, class T>
Q_INLINE_TEMPLATE typename QMap<Key, T>::iterator QMap<Key, T>::insert(const Key &akey, const T &avalue)
{
    detach();
    Node *n = d->root();
    Node *y = d->end();
    Node *last = 0;
    bool  left = true;
    while (n) {
        y = n;
        if (!qMapLessThanKey(n->key, akey)) {
            last = n;
            left = true;
            n = n->leftNode();
        } else {
            left = false;
            n = n->rightNode();
        }
    }
    if (last && !qMapLessThanKey(akey, last->key)) {
        last->value = avalue;
        return iterator(last);
    }
    Node *z = d->createNode(akey, avalue, y, left);
    return iterator(z);
}

The line:

last->value = avalue;

Is the one that creates the problem: you cannot use the =operator directly on a unique_ptr. So now I am puzzeled on what to do next. Is it possible to use QMap and unique_ptr in some other way? Is the whole idea of using QMap and unique_ptr stupid for some reason? What can I do to prevent using naked pointers while still using a QMap?

Answer 1

using Qt container, you should use Qt smart pointers implementation. More about the different implementations in this thread.

What C++ Smart Pointer Implementations are available?

as mentionned, you could go with QSharedPointer.

Answer 2

Of course this isn't going to work, you have created a unique pointer and then you try to copy it into a QMap.

Use a QSharedPointer. When all references to the INuiSensor* instance have been deleted, the instance will be deleted.