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  1. #include <iostream>
  2.  
  3. typedef bool (*Require)(int x);
  4. typedef int  (*Convert)(int x);
  5.  
  6. class Base {
  7. private:
  8. 	int _x;
  9. public:
  10. 	virtual void print() {
  11. 		std::cout << _x << std::endl;
  12. 	}
  13. protected:
  14. 	Base(int x, Require r, Convert c) {
  15. 		if (r(x))
  16. 			_x = x;
  17. 		else
  18. 			_x = c(x);
  19. 	}
  20. };
  21.  
  22. class Derived : public Base {
  23. private:
  24. 	static bool require(int x) {
  25. 		return x >= 0;
  26. 	}
  27. 	static int  convert(int x) {
  28. 		return -1 * x;
  29. 	}
  30. public:
  31. 	Derived(int x) : Base(x, require, convert) {}
  32. };
  33.  
  34. int main() {
  35. 	Derived a(1);
  36. 	Derived b(-1);
  37. 	a.print();
  38. 	b.print();
  39. 	return 0;
  40. }
Success #stdin #stdout 0s 3296KB
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https://ideone.com/rrlbnV
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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