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  1. #include <iostream>
  2. #include <utility>
  3. using namespace std;
  4.  
  5. // ==========================
  6. template <typename F>
  7. void apply(F&&) {}
  8.  
  9. template <typename F, typename First, typename... Rest>
  10. void apply(F&& f, First&& first, Rest&&... rest) {
  11.   std::forward<F>(f)(std::forward<First>(first));
  12.  
  13.   apply(std::forward<F>(f), std::forward<Rest>(rest)...);
  14. }
  15. // ==========================
  16.  
  17.  
  18.  
  19. class A{
  20. public:
  21.     int x, y, z;
  22.  
  23.     A() {
  24.         this->x = 0;
  25.         this->y = 0;
  26.         this->z = 0;
  27.     }
  28.  
  29.     ~A() { }
  30.  
  31.     void init (int x_in, int y_in, int z_in){
  32.         this->x = x_in;
  33.         this->y = y_in;
  34.         this->z = z_in;
  35.     }
  36.  
  37.     int sum(){
  38.         return this->x + this->y + this->z;
  39.     }
  40.  
  41.     void show_result() {
  42.         int result = sum();
  43.         cout << "sum = " << result << endl;
  44.     }
  45. };
  46.  
  47.  
  48.  
  49. #define PP_MEMBER_LIST A_CAR, A_CAT, A_CANADA
  50.  
  51. class B {
  52. public:
  53.     A PP_MEMBER_LIST;
  54.  
  55.     B() {
  56.         A_CAR.init(0, 1, 2);
  57.         A_CAT.init(1, 2, 3);
  58.         A_CANADA.init(8, 7, 6);
  59.     }
  60.  
  61.     ~B() {}
  62.  
  63.     void show_all_result() {
  64.     	const auto show_result = [](A& a) { a.show_result(); };
  65.  
  66.     	apply(show_result, PP_MEMBER_LIST);
  67.     }
  68. };
  69.  
  70.  
  71. int main() { 
  72.  
  73.     B obj_B;
  74.  
  75.     obj_B.show_all_result();
  76. }
  77.  
Success #stdin #stdout 0s 4184KB
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stdin
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Standard input is empty
stdout
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sum = 3
sum = 6
sum = 21
https://ideone.com/pccF6Y
版本3, 利用define與apply()
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
public

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