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  1. #include <iostream>
  2. #include <type_traits>
  3. #include <memory>
  4.  
  5. template<typename Derived>
  6. struct PImplMagic
  7. {
  8. 	PImplMagic()
  9. 	{
  10. 		static_assert(std::is_base_of<PImplMagic, Derived>::value,
  11. 		              "Template parameter must be deriving class");
  12. 	}
  13. //protected: //has to be public, unfortunately
  14. 	struct Impl;
  15. };
  16.  
  17. struct Test : private PImplMagic<Test>, private std::unique_ptr<PImplMagic<Test>::Impl>
  18. {
  19. 	Test();
  20. 	void f();
  21. };
  22.  
  23. int main()
  24. {
  25. 	Test t;
  26. 	t.f();
  27. }
  28.  
  29. template<>
  30. struct PImplMagic<Test>::Impl
  31. {
  32. 	Impl()
  33. 	{
  34. 		std::cout << "It works!" << std::endl;
  35. 	}
  36. 	int x = 7;
  37. };
  38.  
  39. Test::Test()
  40. : std::unique_ptr<Impl>(new Impl)
  41. {
  42. }
  43.  
  44. void Test::f()
  45. {
  46. 	std::cout << (*this)->x << std::endl;
  47. }
  48.  
Success #stdin #stdout 0s 3428KB
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stdin
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Standard input is empty
stdout
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It works!
7
https://ideone.com/WcxJu2
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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