C++ template returning tuple with typename-values

Question

In my journey to implement a template-based linked-list which works with key/value-pairs I want to implement a "popHead()"-method. However, I can't get it to compile.

/**
 * Removes the first element in the list and returns it.
 * @return first element, nullptr if list is empty
 */
std::tuple<K, V> popHead() {
    auto tmp = head;
    if (tmp) {
        if (tmp->next) {
            head = tmp->next;
        } else {
            head = nullptr;
        }
        return new std::tuple(tmp->key, tmp->value);
    }

    return nullptr;
};

This doesn't work because a type-specified is expected. Ok so it doesn't know what kind of type the values contained by the tuple should have.. however.. this doesn't work either:

return new std::tuple<K, V>(tmp->key, tmp->value);

How do I return a tuple with types <K, V>?

Answer 1

Maybe

return {tmp->key, tmp->value};

?

Or, maybe, you want return a pointer to a std::tuple<K, V> ?

In this case

return new std::tuple<K, V>(tmp->key, tmp->value);

should work but you have to modify the return type

std::tuple<K, V> * popHead()
// --------------^ *pointer* to tuple