Is it possible to create a std :: vector <std :: unique_ptr <Bar>> construct using the fill constructor?

Question

I have a Foo class with a member variable of the type std::vector<std::unique_ptr<Bar>>that I would like to populate in the initialization list of the constructor of this class. Is it possible?

I was hoping that using a vector fill constructor would be possible, something like this

Foo::Foo(int n):
    vector<unique_ptr<Bar>> (n, unique_ptr<Bar> (new Bar))
{}

but I believe that this requires a copy constructor std::unique_ptr, which is deleted (as it should be) ( unique_ptr(const unique_ptr&) = delete).

Is there a better way to do this?

Answer 1

Since it is not copied, move it!

Hard coded solution:

#include <memory>
#include <vector>
#include <iterator>
class Bar{};
class Foo{
    public:
    Foo():bars(get_bars()) {}
    std::vector<std::unique_ptr<Bar>> bars;

    private:
    std::vector<std::unique_ptr<Bar>> get_bars(){
        std::unique_ptr<Bar> inilizer_list_temp[]={std::make_unique<Bar>(),std::make_unique<Bar>(),std::make_unique<Bar>()};
        return  std::vector<std::unique_ptr<Bar>>{std::make_move_iterator(std::begin(inilizer_list_temp)),std::make_move_iterator(std::end(inilizer_list_temp))};
    }
};
int main()
{
    Foo foo;
}

Live Demo

:

#include <memory>
#include <vector>
#include <iterator>
#include <iostream>
class Bar{
    public:
    int a=5;
    };
class Foo{
    public:
    Foo():bars(get_bars(10)) {}
    std::vector<std::unique_ptr<Bar>> bars;

    private:
    std::vector<std::unique_ptr<Bar>> get_bars(int n){
        std::vector<std::unique_ptr<Bar>> inilizer_list_temp;
        inilizer_list_temp.reserve(n);
        for(size_t i=0;i<n;++i){
            inilizer_list_temp.emplace_back(std::make_unique<Bar>());
        }
        return inilizer_list_temp;
    }
};
int main()
{
 Foo foo;
 for(auto const& item:foo.bars){
     std::cout << item->a;
 }
}

Live Demo

. - move-only?

EDIT:

++ 11 std:: make_uniuqe:

template<typename T, typename ...Args>
std::unique_ptr<T> make_unique( Args&& ...args )
{
    return std::unique_ptr<T>( new T( std::forward<Args>(args)... ) );
}