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  1. #include <iostream>
  2. #include <tuple>
  3. using namespace std;
  4.  
  5. template<typename T, typename R = conditional_t<is_same<T, char const*>::value, string, T>>
  6. R bar (T &&value) {return value;}
  7.  
  8. template<class Ch, class Tr, class Tuple, std::size_t... Is>
  9. void print_tuple_impl(std::basic_ostream<Ch,Tr>& os,
  10.                       const Tuple & t,
  11.                       std::index_sequence<Is...>)
  12. {
  13.     using swallow = int[]; // guaranties left to right order
  14.     (void)swallow{0, (void(os << (Is == 0? "" : ", ") << std::get<Is>(t)), 0)...};
  15. }
  16.  
  17. template<class Ch, class Tr, class... Args>
  18. decltype(auto) operator<<(std::basic_ostream<Ch, Tr>& os,
  19.                           const std::tuple<Args...>& t)
  20. {
  21.     os << "(";
  22.     print_tuple_impl(os, t, std::index_sequence_for<Args...>{});
  23.     return os << ")";
  24. }
  25.  
  26. template<typename...Args>
  27. decltype(auto) foo(Args...args)
  28. {
  29.     return [args = make_tuple(bar(args)...)] () { cout<< args; return; };
  30. }
  31.  
  32. int main() {
  33. 	// your code goes here
  34. 	string *s = new string("Hello, World!");
  35. 	const char *p = s->c_str();
  36. 	auto f = foo(1, p, 3.14);
  37. 	delete s;
  38. 	f();
  39. 	return 0;
  40. }
Success #stdin #stdout 0s 3468KB
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Standard input is empty
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(1, Hello, World!, 3.14)
https://ideone.com/52XDWj
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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