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  1. #include <iostream>
  2. #include <memory>
  3.  
  4. struct Base
  5. {
  6. 	virtual void exec() { std::cout << "base" << std::endl; }
  7. 	virtual ~Base() { }
  8. };
  9.  
  10. struct Derived1 : public Base
  11. {
  12. 	void exec() override { std::cout << "derived1" <<std::endl; }
  13. };
  14.  
  15. struct Derived2 : public Base
  16. {
  17. 	void exec() override { std::cout << "derived2" << std::endl; }
  18. };
  19.  
  20. template<typename T> struct Wrapper : public T
  21. {
  22. 	bool b{true};
  23. 	using T::T;
  24. };
  25.  
  26. template<typename T> auto& asWrapper(T& mX) 
  27. { 
  28. 	return static_cast<Wrapper<T>&>(mX); 
  29. }
  30.  
  31. template<typename T, typename TWrapper> auto& asT(TWrapper& mX) 
  32. { 
  33. 	return reinterpret_cast<T&>(mX); 
  34. }
  35.  
  36. int main()
  37. {
  38. 	auto d1 = std::make_unique<Wrapper<Derived1>>();
  39. 	auto d2 = std::make_unique<Wrapper<Derived2>>();
  40.  
  41. 	Base* bd1 = d1.get();
  42. 	Base* bd2 = d2.get();
  43.  
  44. 	bd1->exec();
  45. 	bd2->exec();
  46.  
  47. 	auto& bl1 = asWrapper(*bd1);
  48. 	auto& bl2 = asWrapper(*bd2);
  49.  
  50. 	std::cout << bl1.b << " " << bl2.b << std::endl;
  51. 	bl1.b = false;
  52. 	std::cout << bl1.b << " " << bl2.b << std::endl;
  53. 	bl2.b = false;
  54. 	std::cout << bl1.b << " " << bl2.b << std::endl;
  55.  
  56. 	asT<Derived1>(bl1).exec();
  57. 	asT<Derived2>(bl2).exec();
  58.  
  59. 	return 0;
  60. }
Success #stdin #stdout 0s 3276KB
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derived1
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0 1
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https://ideone.com/MRy9Hy
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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