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  1. #include <iostream>
  2. #include <functional>
  3. #include <string>
  4. #include <sstream>
  5.  
  6. struct Variant
  7. {
  8.     template<typename T>
  9.     explicit Variant(T x) { std::stringstream ss; ss << x; impl = ss.str(); }
  10.  
  11.     std::string impl;
  12. };
  13.  
  14. template<typename T>
  15. T cast(Variant v) { std::stringstream ss(v.impl); T t; ss >> t; return t; }
  16.  
  17. namespace details
  18. {
  19.     template<typename...T>struct Aux;
  20.  
  21.     template<typename H, typename...T>
  22.     struct Aux<H, T...> : Aux<T...>
  23.     {
  24.         template<typename F, typename... A>
  25.         Aux(F f, Variant* args, A... a) : Aux<T...>(f, args + 1, a..., cast<H>(*args)) {}
  26.     };
  27.  
  28.     template<>
  29.     struct Aux<>
  30.     {
  31.         template<typename F, typename... A>
  32.         Aux(F f, Variant* args, A... a) { f(a...); }
  33.     };
  34. }
  35.  
  36. template<typename... Ts>
  37. void invoke(std::function<void(Ts...)> f, Variant* args)
  38. {
  39.     details::Aux<Ts...>{f, args};
  40. }
  41.  
  42. int main()
  43. {
  44.     std::function<void(int, double, std::string)> test = [](int a, double b, std::string c)
  45.     {
  46.         std::cout << "a=" << a << '\n';
  47.         std::cout << "b=" << b << '\n';
  48.         std::cout << "c=" << c << '\n';
  49.     };
  50.  
  51.     Variant a[] = {Variant("20"), Variant("1.5"), Variant("x")};
  52.     invoke(test, a);
  53. }
  54.  
Success #stdin #stdout 0s 3072KB
comments (?)
stdin
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Standard input is empty
stdout
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a=20
b=1.5
c=x
https://ideone.com/DbRDvD
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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