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  1. #include <iostream>
  2. #include <list>
  3. #include <memory>
  4. using namespace std;
  5.  
  6. struct Connection
  7. {
  8. 	Connection()
  9. 	{
  10. 		std::cout << "Connection()" << std::endl;
  11. 	}
  12.  
  13. 	~Connection()
  14. 	{
  15. 		std::cout << "~Connection()" << std::endl;
  16. 	}
  17. };
  18.  
  19. typedef shared_ptr<Connection> ptr_t;
  20.  
  21. class ConnectionReleaser {
  22.     list<ptr_t>& whereToReturn;
  23.     ptr_t connectionToRelease;
  24.     int ver;
  25.     static int nextVer;
  26. public:
  27.     ConnectionReleaser(list<ptr_t>& lst, const ptr_t& x)
  28.     	: whereToReturn(lst)
  29.     	, connectionToRelease(x)
  30.     {
  31.     	ver = nextVer++;
  32. 		std::cout << "ConnectionReleaser() v." << ver << std::endl;
  33.     }
  34.  
  35.     ConnectionReleaser(const ConnectionReleaser& rhs)
  36.     	: whereToReturn(rhs.whereToReturn)
  37.     	, connectionToRelease(rhs.connectionToRelease)
  38.     {
  39.     	ver = nextVer++;
  40. 		std::cout << "ConnectionReleaser(rhs v." << rhs.ver << ") v." << ver << std::endl;
  41.     }
  42.  
  43. 	~ConnectionReleaser()
  44. 	{
  45. 		std::cout << "~ConnectionReleaser() v." << ver << std::endl;
  46. 	}
  47.  
  48.     void operator()(Connection*) {
  49.         whereToReturn.push_back( connectionToRelease );
  50. 		// Обратите внимание на следующую строчку
  51.         //connectionToRelease.reset();
  52.     }
  53. };
  54.  
  55. int ConnectionReleaser::nextVer = 0;
  56.  
  57.  
  58. list<ptr_t> connectionList;
  59.  
  60. ptr_t getConnection() {
  61. 	std::cout << "enter getConnection()" << std::endl;
  62.     ptr_t c( connectionList.back() );
  63.     connectionList.pop_back();
  64.     ptr_t r( c.get(), ConnectionReleaser( connectionList, c ) );
  65. 	std::cout << "exit getConnection()" << std::endl;
  66.     return r; 
  67. }
  68.  
  69. int main() {
  70. 	connectionList.push_back(make_shared<Connection>());
  71.  
  72. 	{
  73. 	    weak_ptr<Connection> weak1;
  74. 		cout << "connectionList.size() = " << connectionList.size() << endl;
  75. 		auto c = getConnection();
  76. 		cout << "connectionList.size() = " << connectionList.size() << endl;
  77. 		weak1 = c;
  78. 		cout << "weak1.expired() = " << weak1.expired() << endl;
  79. 		cout << "begin c.reset()" << endl;
  80. 		c.reset();
  81. 		cout << "end c.reset()" << endl;
  82. 		cout << "weak1.expired() = " << weak1.expired() << endl;
  83. 		cout << "connectionList.size() = " << connectionList.size() << endl;
  84. 		cout << "deleting weak1" << endl;
  85. 	}
  86.  
  87. 	return 0;
  88. }
Success #stdin #stdout 0s 3440KB
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Standard input is empty
stdout
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Connection()
connectionList.size() = 1
enter getConnection()
ConnectionReleaser() v.0
ConnectionReleaser(rhs v.0) v.1
ConnectionReleaser(rhs v.1) v.2
ConnectionReleaser(rhs v.2) v.3
ConnectionReleaser(rhs v.3) v.4
ConnectionReleaser(rhs v.4) v.5
~ConnectionReleaser() v.4
~ConnectionReleaser() v.3
~ConnectionReleaser() v.2
~ConnectionReleaser() v.1
~ConnectionReleaser() v.0
exit getConnection()
connectionList.size() = 0
weak1.expired() = 0
begin c.reset()
end c.reset()
weak1.expired() = 1
connectionList.size() = 1
deleting weak1
~ConnectionReleaser() v.5
~Connection()
https://ideone.com/kR7OBv
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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