How to construct non-copyable object in vector of tuples?

Question

I have a non-copyable class A that I want to move into a vector of tuples (see code below). I understand why the code below is not working, but I'm wondering if there is a clever way to make it work without changing the implementation of my class. Any help is greatly appreciated. Thanks :)

#include <iostream>
#include <vector>
#include <tuple>

class A {
    public:
    int val1;
    int val2;

    A(int v1, int v2): val1(v1), val2(v2) {}

    // make non-copyable
    A(const A &other) = delete;
    A &operator=(const A &other) = delete;
};

int main() {
    std::vector<std::tuple<int, int, A>> my_as;

    my_as.emplace_back(4, 3, A(4, 2)); // Error, how to fix this?

    return 0;
}

I take it you are against or can't make `A` moveable? – NathanOliver May 02 '23 at 03:01 — NathanOliver, May 02 '23 at 03:01

score 0 · Accepted Answer · answered May 02 '23 at 02:56

One possible way to solve this may be to use unique pointers like this.


#include <iostream>
#include <vector>
#include <tuple>
#include <memory>

class A {
    public:
    int val1;
    int val2;

    A(int v1, int v2): val1(v1), val2(v2) {}

    // make non-copyable
    A(const A &other) = delete;
    A &operator=(const A &other) = delete;
};

int main() {
    std::vector<std::tuple<int, int, std::unique_ptr<A>>> my_as;

    my_as.emplace_back(4, 3, std::make_unique<A>(4, 2));
    return 0;
}

This also allows the vector to grow, which is a nice feature. — NathanOliver, May 02 '23 at 02:58

How to construct non-copyable object in vector of tuples?

1 Answers1