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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. using namespace std;
  5.  
  6. enum typeData
  7. {
  8. 	ValueDouble,
  9. 	ValueFloat
  10. };
  11.  
  12. struct data
  13. {
  14.     typeData TypeData;
  15.     vector<double> getDoubleValues() const { return vector<double>(); }
  16.     vector<float> getFloatValues() const { return vector<float>(); }
  17. };
  18.  
  19. template <typename R, typename F>
  20. R Dispatch(const data& d, F f)
  21. {
  22.   switch (d.TypeData)
  23.   {
  24.    case ValueDouble: return f(d.getDoubleValues());
  25.    case ValueFloat: return f(d.getFloatValues());
  26.    default: break; // ?
  27.   }
  28. }
  29.  
  30. //usage
  31. int func(const std::vector<double>& v)
  32. {
  33.   return v.size();
  34. }
  35.  
  36. int func(const std::vector<float>& v)
  37. {
  38.   return v.size() + 1;
  39. }
  40.  
  41. template <typename T>
  42. struct D
  43. {
  44.   template <typename V>
  45.   T operator()(const std::vector<V>& v) const { return func(v); }
  46. };
  47.  
  48. int main()
  49. {
  50. 	data d;
  51.     d.TypeData = ValueDouble;
  52.  
  53.     int h1 = Dispatch<int>(d, D<int>());
  54.     cout << "h1 = " << h1 << endl;
  55.  
  56.     d.TypeData = ValueFloat;
  57.     int h2 = Dispatch<int>(d, D<int>());
  58.     cout << "h2 = " << h2 << endl;
  59. 	return 0;
  60. }
Success #stdin #stdout 0s 3140KB
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stdin
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Standard input is empty
stdout
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h1 = 0
h2 = 1
https://ideone.com/4Tlhkd
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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