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  1. #include <iostream>
  2. #include <tuple>
  3.  
  4. struct Result
  5. {
  6.     Result() : m_success(true) {}
  7.     explicit operator bool() const { return !m_success; }
  8.     bool m_success;
  9. };
  10.  
  11. template<unsigned index, typename... Types>
  12. struct TupleItemDeleter
  13. {
  14.     void operator() (std::tuple<Types...>& t)
  15.     {
  16.         std::cout << "Deleting item at index " << index << std::endl;
  17.         delete std::get<index>(t);
  18.         TupleItemDeleter<index - 1, Types...>{}(t);
  19.     }
  20. };
  21.  
  22. template<typename... Types>
  23. struct TupleItemDeleter<0, Types...> 
  24. {
  25.     void operator() (std::tuple<Types...>& t)
  26.     {
  27.         std::cout << "Deleting item at index 0" << std::endl;
  28.         delete std::get<0>(t);
  29.     }
  30. };
  31.  
  32. template<typename... Types>
  33. void deleter(std::tuple<Types...>& t)
  34. {
  35.     constexpr auto tupleSize = std::tuple_size<std::tuple<Types...>>::value;
  36.     TupleItemDeleter<tupleSize - 1, Types...>{}(t);
  37. }
  38.  
  39.  
  40. template<typename... T>
  41. struct CleanupHelper {
  42.  
  43.     CleanupHelper (const Result& res, const std::tuple<T...>& itemsToDelete)
  44.      : m_result(res)
  45.      , m_itemsToDelete(itemsToDelete)
  46.     {
  47.     }
  48.  
  49.     ~CleanupHelper()
  50.     {
  51.         if(!m_result)
  52.         {
  53.            deleter(m_itemsToDelete);
  54.         }
  55.     }
  56.  
  57.     const Result& m_result;
  58.     std::tuple<T...> m_itemsToDelete;
  59. };
  60.  
  61. struct Foo {};
  62.  
  63. Result functionThatNeedsCleanup()
  64. {
  65. 	Result res;
  66. 	Foo *pFoos_1, *pFoos_2;
  67. 	CleanupHelper<Foo*,Foo*> cleanupHelper(res, std::make_tuple(pFoos_1, pFoos_2));
  68. 	try
  69. 	{
  70. 		pFoos_1 = new Foo;
  71. 		pFoos_2 = new Foo[10];
  72. 		//
  73. 		// Do work
  74. 		//
  75. 	}
  76. 	catch(...)
  77. 	{
  78. 		res.m_success = false;
  79. 	}
  80. }
  81.  
  82. int main()
  83. {
  84.   functionThatNeedsCleanup();
  85.   return 0;
  86. }
Success #stdin #stdout 0s 4140KB
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Standard input is empty
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Deleting item at index 1
Deleting item at index 0
https://ideone.com/nqp2HC
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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