C++11 _format suffix literal for .format() like string arguments.

suffix.cpp

#include <string>
#include <vector>
#include <sstream>
#include <exception>

namespace std {
std::string to_string(const char* value)
{
    return std::string(value);
}
}

struct StringFormat {
    std::string fmt;
    std::vector<std::string> arguments;

    StringFormat(std::string fmt)
        : fmt(fmt) {}

    template <typename T, typename ...Tail>
    std::string operator()(const T& t, Tail&&... tail)
    {
        arguments.push_back(std::to_string(t));
        return operator()(std::forward<Tail>(tail)...);
    }

    std::string operator()()
    {
        size_t found = 0;
        const std::string grep = "{}";
        auto arg_begin = arguments.cbegin();
        auto arg_end = arguments.cend();

        while ((found = fmt.find(grep, found)) != std::string::npos) {
            if (arg_begin == arg_end)
                throw std::range_error{"args out of range for '{}'"};
            fmt.replace(found, grep.size(), *arg_begin);
            ++arg_begin;
        }

        return fmt;
    }
};

StringFormat operator"" _format (const char* fmt, size_t len)
{
    return StringFormat(fmt);
}

int main()
{
    std::cout << "Hello {}! You're {} years old.\n"_format("Justin", 23);
}