Passing std::array as arguments of template variadic function

Question

I am trying to learn about variadic templates in C++11. I have a class which is basically a wrapper around a std::array. I want to be able to pass function obje

Answer 1

Given the well-known indices infrastructure:

namespace detail
{
    template
    struct seq { };

    template
    struct gen_seq : gen_seq { };

    template
    struct gen_seq<0, Is...> : seq { };
}

You could redefine your class template this way:

template
struct Container {
    template
    Container(Ts&&... vs) : data{{std::forward(vs)...}} {
        static_assert(sizeof...(Ts)==N,"Not enough args supplied!");
    }

    template
    void doOperation(F&& func)
    {
        doOperation(std::forward(func), detail::gen_seq());
    }

    template
    void doOperation(F&& func, detail::seq)
    {
        (std::forward(func))(data[Is]...);
    }

    std::array data;
};

Here is a live example.

Notice, that you do not need to construct an std::function object in main(): the std::function can be implicitly constructed from the lambda. However, you do not even need to use std::function at all here, possibly incurring in an unnecessary run-time overhead.

In the solution above, I just let the type of the callable object to be a template parameter that can be deduced by the compiler.