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  1. #include <iostream>
  2. #include <map>
  3. #include <functional> // std::ref
  4. #include <vector>
  5.  
  6. class Foo
  7. {
  8. public:
  9.     template <typename ...Ts>
  10.     Foo(Ts&&... ts)  : Foo(std::map<char, std::vector<int>&>{std::forward<Ts>(ts)...}) {}
  11.  
  12.     Foo(std::vector<int> (&v)[26]) :
  13.     A(v[0]),
  14.     B(v[1])
  15.     // and so on...
  16.     {
  17.     }
  18.  
  19.     Foo(std::vector<int> &a, std::vector<int> &b) : A(a), B(b) // and so on...
  20.     {
  21.     }
  22.  
  23.     Foo(const std::map<char, std::vector<int>&>& m) :
  24.     A(m.at('A')),
  25.     B(m.at('B'))
  26.     // and so on...
  27.     {
  28.     }
  29.     Foo(std::map<char, std::vector<int>&>&& m) :
  30.     A(m.at('A')),
  31.     B(m.at('B'))
  32.     // and so on...
  33.     {
  34.     }
  35.  
  36.     virtual void DoSomething()
  37.     {
  38.         A.push_back(42);
  39.         std::cout << A[0] << std::endl;
  40.     }
  41.  
  42. private:
  43.     std::vector<int> &A, &B; //, &C, &D, &E, &F, &G; // and so on...
  44. };
  45.  
  46.  
  47. int main()
  48. {
  49.     {
  50.         std::vector<int> v[26];
  51.  
  52.         Foo foo(
  53.             std::make_pair('A', std::ref(v[0])),
  54.             std::make_pair('B', std::ref(v[1]))
  55.             // And so on...
  56.         );
  57.  
  58.         foo.DoSomething();
  59.         std::cout << v[0][0] << std::endl;
  60.     }
  61.     {
  62.         std::vector<int> v[26];
  63.  
  64.         Foo foo(v);
  65.  
  66.         foo.DoSomething();
  67.         std::cout << v[0][0] << std::endl;
  68.  
  69.     }
  70.     {
  71.         std::vector<int> v[26];
  72.  
  73.         Foo foo(v[0], v[1]);
  74.  
  75.         foo.DoSomething();
  76.         std::cout << v[0][0] << std::endl;
  77.  
  78.     }
  79.     {
  80.         std::vector<int> v[26];
  81.         const std::map<char, std::vector<int>&> m {
  82.             std::make_pair('A', std::ref(v[0])),
  83.             std::make_pair('B', std::ref(v[1]))
  84.             // And so on...
  85.         };
  86.         Foo foo(m);
  87.  
  88.         foo.DoSomething();
  89.         std::cout << v[0][0] << std::endl;
  90.     }
  91.     return 0;
  92. }
  93.  
Success #stdin #stdout 0s 3480KB
comments (?)
stdin 
Standard input is empty
stdout 
42
42
42
42
42
42
42
42
https://ideone.com/RjzvVj
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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