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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. template <typename ...Funcs>
  5. struct overload_set;
  6.  
  7. template <typename Head, typename ...Tail>
  8. struct overload_set<Head, Tail...> : Head, overload_set < Tail... >
  9. {
  10. 	overload_set(Head head, Tail... tail)
  11. 	: Head(head)
  12. 	, overload_set < Tail... > (tail...)
  13. 	{}
  14.  
  15. 	using Head::operator();
  16. 	using overload_set<Tail...>::operator();
  17. };
  18.  
  19. template <typename Func>
  20. struct overload_set<Func> : Func
  21. {
  22. 	overload_set(Func func)
  23. 	: Func(func)
  24. 	{}
  25.  
  26. 	using Func::operator();
  27. };
  28.  
  29. template <typename ...Funcs>
  30. overload_set<Funcs...> overload(Funcs... funcs)
  31. {
  32. 	return overload_set < Funcs... > (funcs...);
  33. }
  34.  
  35. int main()
  36. {
  37. 	auto f = overload(
  38. 		[] { return 1; },                // 1
  39. 		[](int x) { return x + 1; },    // 2
  40. 		[](double x) { return 2 * x; }  // 3
  41. 	);
  42.  
  43. 	using std::cout;
  44. 	using std::endl;
  45. 	cout << f() << endl         // call 1
  46. 		<< f(1) << endl        // call 2
  47. 		<< f(2.0) << endl;     // call 3
  48.  
  49. 	return 0;
  50. }
Success #stdin #stdout 0s 3096KB
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https://ideone.com/WPYJhi
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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