generic_tostring_7.cpp

#include <iostream>
#include <string>
#include <utility>
#include <type_traits>

auto toString(bool b)
{
    return b ? "true" : "false";
}

template <typename T>
auto toString(T&& val) -> decltype(std::to_string(std::declval<T>()))
{
    return std::to_string(val);
}

template <typename T>
auto toString(T&& val) -> decltype(std::string(std::declval<T>()))
{
    return val;
}

template <typename T>
auto toString(T&& val) -> decltype(std::declval<T>().toString())
{
    return val.toString();
}

//////////////////////////////////////////////////

struct Pos
{
    int x, y;

    std::string toString() const
    {
        return "x: " + std::to_string(x) + ", y: " + std::to_string(y);
    }
};


template <typename ...Args>
void print(const Args&... args)
{
    (std::cout << ... << (toString(args) + std::string{ "\n" }));
}

int main()
{
    int foo{ -20 };
    double bar{ 13.22 };
    bool baz{ false };
    std::string qux{ "qux" };
    Pos alohomora{ 20, 40 };

    print(foo, bar, baz, qux, "Pos: ", alohomora);

    return 0;
}