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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4.  
  5. template<typename T, typename V>
  6. class Property {
  7. private:
  8. 	T* ref;
  9. 	V (*fn)(T);
  10.  
  11. public:
  12. 	Property(T* val, V (*fn)(T)) {
  13. 		this->ref = val;
  14. 		this->fn = fn;
  15. 	}
  16.  
  17. 	V operator()() {
  18. 		return fn(*ref);
  19. 	}
  20.  
  21. 	template<typename T2, typename V2>
  22. 	friend ostream& operator<<(ostream& o, Property<T2, V2> p) {
  23. 		o << p();
  24. 		return o;
  25. 	}
  26.  
  27. };
  28.  
  29. template<typename T, typename V>
  30. void print_stuff(Property<T, V> p) {
  31. 	cout << p << endl;
  32. }
  33.  
  34. int main() {
  35. 	int* a = new int();
  36. 	*a = 25;
  37. 	Property<int, double> b(a, sqrt);
  38. 	print_stuff(b);
  39. 	*a = 36;
  40. 	print_stuff(b);
  41. 	delete a;
  42. 	return 0;
  43. }
Success #stdin #stdout 0s 3460KB
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https://ideone.com/Aut4dO
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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