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  1. #include <functional>
  2. #include <tuple>
  3.  
  4. // apply a functor to every element of a tuple
  5. namespace Detail {
  6. template <std::size_t i, typename Tuple, typename F>
  7. typename std::enable_if<i == std::tuple_size<Tuple>::value>::type
  8. ForEachTupleImpl(Tuple& t, F& f)
  9. {
  10. }
  11.  
  12. template <std::size_t i, typename Tuple, typename F>
  13. typename std::enable_if<i != std::tuple_size<Tuple>::value>::type
  14. ForEachTupleImpl(Tuple& t, F& f)
  15. {
  16.     f(std::get<i>(t));
  17.     ForEachTupleImpl<i+1>(t, f);
  18. }
  19.  
  20. }
  21.  
  22. template <typename Tuple, typename F>
  23. void ForEachTuple(Tuple& t, F& f)
  24. {
  25.     Detail::ForEachTupleImpl<0>(t, f);
  26. }
  27.  
  28. struct A
  29. {
  30.     A() : a(0) {}
  31.     A(A& a) = delete;
  32.     A(const A& a) = delete;
  33.  
  34.     int a;
  35. };
  36.  
  37. int main()
  38. {
  39.     // create a tuple of types and initialise them with zeros
  40.     using T = std::tuple<A, A, A>;
  41.     T t;
  42.  
  43.     // creator a simple function object that increments the objects member
  44.     struct F
  45.     {
  46.         void operator()(A& a) const { a.a++; }
  47.     } f;
  48.  
  49.     // if this works I should end up with a tuple of A's with members equal to 1
  50.     ForEachTuple(t, f);
  51.     return 0;
  52. }
Success #stdin #stdout 0s 3336KB
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https://ideone.com/b8nLCy
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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