Call function with part of variadic arguments

Question

Consider I have the following:

void bar(int a, int b)
{
}   

template
void foo(F function, Args... args>
{
    function(a         


        

Answer 1

Here is a solution that will work with anything std::invoke accepts, that invokes the overload with the fewest possible arguments.

template 
decltype(auto) invoke_front_impl(F&& f, Args&& args, std::index_sequence)
{
    if constexpr (std::is_invocable_v...>) {
        return std::invoke(std::forward(f), std::get(std::move(args))...);
    } else {
        return invoke_front_impl(
            std::forward(f),
            std::move(args),
            std::make_index_sequence());
    }
}

template 
decltype(auto) invoke_front(F&& f, Args&&... args)
{
    return invoke_front_impl(
        std::forward(f),
        std::forward_as_tuple(std::forward(args)...),
        std::make_index_sequence<0>());
}

Demo on Wandbox