c++ - 可変長initializer_list

Question

c++ で可変長の initializer_list を作成する可能性はありますか?

例として:

std::list<string>  mylist { somemagic (listSize, "default") };

または：

QList<MyClass>     anotherList { somemagic (listSize, {MyClassInitializerHere} ) };

Answer 1

以下を使用できます: ( https://ideone.com/eQstbh )

#include <initializer_list>

#if 1 // Not in C++11 // make_index_sequence
#include <cstdint>

template <std::size_t...> struct index_sequence {};

template <std::size_t N, std::size_t... Is>
struct make_index_sequence : make_index_sequence<N - 1, N - 1, Is...> {};

template <std::size_t... Is>
struct make_index_sequence<0u, Is...> : index_sequence<Is...> {};

#endif // make_index_sequence

namespace detail
{
    template <std::size_t... Is, typename T>
    std::initializer_list<T> make_initializer_list(const T& t, index_sequence<Is...>)
    {
        return { (static_cast<void>(Is), t)... };
    }
}


template <std::size_t N, typename T>
std::initializer_list<T> make_initializer_list(const T& t)
{
    return detail::make_initializer_list(t, make_index_sequence<N>());
}