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Exceptions in Destructors


When dog objects in main() go out of scope, it invokes destructor. Since destructor throws an exception, due to multiple exception condition program crashes.

class dog {
public:
string m_name;
dog(string name) 
{ 
m_name = name; 
cout << name << " is born." << endl; 
}

 ~dog() 
{ 
cout << m_name << " is distroied.\n" << endl;
throw 10;
}
};

 int main()
{
try {
dog dog1("Henry");
dog dog2("Bob");
}
catch (int e) {
cout << e << " is caught" << endl;
}
return 1;
}

Solution 1: Destructor swallow the exception

 ~dog() { 
      try {
         // Enclose all the exception prone code here
      } catch (MYEXCEPTION e) {
         // Catch exception
      } catch (...) {
      }

   }

Solution 2:  Move the exception-prone code to a different function

 class dog {
public:
         string m_name;
         dog(string name) {m_name = name; cout << name << " is born." << endl; }
 
                ~dog() { cout<< m_name << " is distroied.\n" << endl; }
                 void prepareToDestr() { throw 20; }
                 void bark() {cout<< m_name << " 's dog is barking.\n" << endl; }


};
int main{} {
  try {
     dog dog1("Henry");
     dog dog2("Bob");
     dog1.bark(); 
     dog2.bark();
     dog1.prepareToDestr();
     dog2.prepareToDestr();
  } catch (int e) {
  cout << e << " is caught" << endl;  // Only Exception of dog1 is caught
  }

}

Note: Destructor in main

 class dog {
public:
         string m_name;
         dog(string name) {m_name = name; cout << name << " is born." << endl; }
 
                ~dog() { cout<< m_name << " is destroyed.\n" << endl; }
                
                 void bark() {cout<< m_name << " 's dog is barking.\n" << endl; }  // It never gets invokes


};
int main{} {
  try {
     dog dog1("Henry");
     dog dog2("Bob");
   
      throw 20;

      dog1.bark(); 
     dog2.bark();
     
  } catch (int e) {
  cout << e << " is caught" << endl;  // Exception of dog1 is caught
  }

}
Output:

 Henry is born.
Bob is born.
Bob is distroied.
Henry is distroied.
20 is caught

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