Apply a function to each arguments abusing C++17 upcoming fold expressions and operator coma (compiling with Clang 3.6 and above)

ForEachArgs.hxx

#include <initializer_list>

// The original version, by Eric Niebler and Sean Parent. Abusing brace initialization to make a liste expansion.
// Would work with any variadic initializable construct, such as array types (T[])

template<class Fn, class ... Args>
constexpr Fn for_each_args(Fn f, Args&& ... args)
{
    using expander = std::initializer_list<int>;
    return ((void)expander{(f(args), 0)...}, f);
}

// Here is the version I came up with using fold expressions. In fact, this is the same principle, but you do
// no longer need to abuse a variadic initializable type to achieve the same effect. Same code generation also.

template<class Fn, class ... Args>
constexpr Fn for_each_args(Fn f, Args&& ... args)
{
    return ((..., f(std::forward<Args>(args))), f);
}

// Sample usage : 

class Ostreamer
{
    public:
    template<class T>
    void operator()(T x)
    {
        std::cout << x << std::endl;
    }  
};

class BasicStreamable
{};

std::ostream& operator<<(std::ostream& os, BasicStreamable)
{
    os << "I'm a streamable !\n";
    return os;
}

for_each_args(Ostreamer{}, 1, 9, 18, 5, "Hello", " World !", BasicStreamable{});

// Or, if your compiler supports generic lambda functions, you can get read of the "Ostreamer" proxy 
for_each_args([](auto x) {
    std::cout << x << std::endl;
}, 1, 9, 18, 5, "Hello", " World !", BasicStreamable{});