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  1. #include <memory>
  2. #include <iostream>
  3.  
  4. 	template<class T>
  5. 	struct call_with_pointer {
  6. 		// last resort: T*
  7. 		template<class Callable>
  8. 		static auto call(Callable &callable, const std::shared_ptr<T> &param) -> decltype(callable(param.get())) {
  9. 			return callable(param.get());
  10. 		}
  11. 	};
  12.  
  13. 	template<class T>
  14. 	struct call_with_shared : public call_with_pointer<T> {
  15.  
  16. 		// best: call with shared_ptr<T>.
  17. 		// SFINA
  18. 		template<class Callable>
  19. 		static auto call(Callable &callable, const std::shared_ptr<T> &param) -> decltype(callable(param)) {
  20. 			return callable(param);
  21. 		}
  22.  
  23. 		using call_with_pointer<T>::call;
  24.  
  25. 	};
  26.  
  27.  
  28. class Test {
  29. public:
  30. 	bool operator () (int * x) {
  31. 		return *x == 42;
  32. 	}
  33. };
  34.  
  35. using namespace std;
  36.  
  37. int main (int argc, const char * argv[])
  38. {
  39. 	{
  40. 		Test t;
  41.  
  42. 		auto i = std::make_shared<int>(4);
  43.  
  44. 		auto x = call_with_shared<int>::call(t, i);
  45. 	}
  46.  
  47. 	return 0;
  48. }
  49.  
Success #stdin #stdout 0s 3060KB
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stdout 
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https://ideone.com/5pkSf
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
secret

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