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  1. #include <memory>
  2.  
  3. template<class T>
  4. class Handle : public std::shared_ptr<T> {
  5. public:
  6. 	using std::shared_ptr<T>::shared_ptr;
  7.     template<class ResultType>
  8.     inline Handle<ResultType>
  9.     cast() const {
  10.         // Cast Handle to shared_ptr
  11.         auto T_sp = static_cast< std::shared_ptr<T> >(*this);
  12.         // Cast the data
  13.         auto ResultType_sp = std::static_pointer_cast<ResultType>(T_sp);
  14.         // Cast back to Handle
  15.         return static_cast< Handle<ResultType> >(ResultType_sp);
  16.     }
  17. };
  18.  
  19.  
  20. // Usage
  21. struct Base {};
  22. struct Child : public Base {};
  23.  
  24. int main() {
  25. 	auto child_ptr = Handle<Child>(new Child());
  26. 	auto base_ptr  = child_ptr.cast<Base>(); // Error with this
  27.  
  28. 	return 0;
  29. }
Success #stdin #stdout 0s 3224KB
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https://ideone.com/nbPHbs
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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