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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. namespace mylib {
  5. 	struct Person {
  6. 		static int counter; 
  7. 		int id; 
  8. 		Person() : id(++counter) {}
  9. 		void whoami() { cout << "I'm "<<id<<endl; }
  10. 	};  //A
  11. 	struct Friend: Person {}; //B -> A
  12. 	int Person::counter=0; 
  13. }
  14. class Employee { 
  15. 	mylib::Person *a;
  16. 	bool owna;
  17. protected:
  18. 	Employee (mylib::Person& x) : a(&x), owna(false) { }  // use existing A
  19. public: 
  20. 	Employee () : a(new mylib::Person), owna(true) { }     
  21. 	~Employee () { if (owna) delete a; }
  22. 	void whoami() { a->whoami(); } // A - fowarding 
  23. };
  24. struct Colleague : mylib::Friend, Employee { 
  25. 	Colleague () : mylib::Friend(), Employee(*static_cast<Person*>(this)) {}; 
  26. 	using Friend::whoami; 
  27. }; 
  28.  
  29. int main() {
  30. 	mylib::Friend p1;   // ok !  
  31. 	p1.whoami(); 
  32.  
  33. 	Employee p2; 
  34. 	p2.whoami(); 
  35.  
  36. 	Colleague p3;   // No diamond ! 
  37. 	p3.whoami();  // ouch !! not allowed: no diamond so the function has to be called for which base object ? 
  38. 	p3.Employee::whoami();   // first occurence of A
  39. 	p3.mylib::Friend::whoami(); // second second occurence of A
  40.  
  41. 	return 0;
  42. }
Success #stdin #stdout 0s 3468KB
comments (?)
stdin
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Standard input is empty
stdout
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I'm 1
I'm 2
I'm 3
I'm 3
I'm 3
https://ideone.com/9R82uc
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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