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  1. #include <cstdio>
  2.  
  3. #include <string>
  4. #include <tuple>
  5. #include <utility>
  6.  
  7. template <typename T>
  8. struct get_specifier;
  9.  
  10. template <>
  11. struct get_specifier<int> {
  12.     static constexpr char const* value = "%d";
  13. };
  14.  
  15. template <>
  16. struct get_specifier<char const*> {
  17.     static constexpr char const* value = "%s";
  18. };
  19.  
  20. template <>
  21. struct get_specifier<double> {
  22.     static constexpr char const* value = "%f";
  23. };
  24.  
  25. template <size_t, typename>
  26. struct format_runner;
  27.  
  28. template <size_t Index, typename... Ts>
  29. struct format_runner<Index, std::tuple<Ts...>> {
  30.     using tuple_type = std::tuple<Ts...>;
  31.  
  32.     template <typename String>
  33.     static String execute(String&& init) {
  34.         return format_runner<Index-1, tuple_type>::execute(std::forward<String>(init))
  35.                + " "
  36.                + get_specifier<
  37.                   typename std::tuple_element<Index, tuple_type>::type
  38.                >::value;
  39.     }
  40. };
  41.  
  42. template <typename... Ts>
  43. struct format_runner<0, std::tuple<Ts...>> {
  44.     using tuple_type = std::tuple<Ts...>;
  45.  
  46.     template <typename String>
  47.     static String execute(String&& init) {
  48.         return init + get_specifier<
  49.                   typename std::tuple_element<0, tuple_type>::type
  50.                >::value;
  51.     }
  52. };
  53.  
  54. template <typename String, typename... Ts>
  55. String format(String&& init, Ts&&... values) {
  56.     return format_runner<
  57.         sizeof...(Ts)-1,
  58.         std::tuple<typename std::remove_reference<Ts>::type...>
  59.     >::execute(std::forward<String>(init));
  60. }
  61.  
  62. template <typename... Ts>
  63. int redisCommand(char const* prefix, Ts&&... values) {
  64.     return std::printf(
  65.         format(std::string(prefix), values...).c_str(),
  66.         values...
  67.     );
  68. }
  69.  
  70. int main() {
  71.     char const* value1 = "1";
  72.     int value2 = 2;
  73.     double value3 = 3.0;
  74.  
  75.     redisCommand("SET foo ", value1, value2, value3);
  76. }
Success #stdin #stdout 0s 2984KB
comments (?)
stdin 
Standard input is empty
stdout 
SET foo 1 2 3.000000
https://ideone.com/dLjgZY
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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