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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class Wrapper
  5. {
  6.   std::vector<int> const& bc;
  7. public:
  8.   Wrapper(std::vector<int> const& bc) : bc(bc) { }
  9.   int GetSize() const { return bc.size(); }
  10. };
  11.  
  12. class Adapter
  13. {
  14.   Wrapper wrapper;
  15. public:
  16.   Adapter(Wrapper&& w) : wrapper(w) { }
  17.   int GetSize() const { return wrapper.GetSize(); }
  18. };
  19.  
  20. template <class T>
  21. class Mixin : public Adapter
  22. {
  23. public:
  24.   //< Replace "Types ... args" with "Types& ... args" and it works!
  25.   template <class ... Types>
  26.   Mixin(Types ... args) : Adapter(T(args...)) { }
  27. };
  28.  
  29. int main()
  30. {
  31.   std::vector<int> data;
  32.   data.push_back(5);
  33.   data.push_back(42);
  34.   Mixin<std::vector<int>> mixin(data);
  35.   std::cout << "data:  " << data.size() << "\n";
  36.   std::cout << "mixin: " << mixin.GetSize() << "\n";
  37.   return 0;
  38. }
Success #stdin #stdout 0s 3456KB
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stdin
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Standard input is empty
stdout
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data:  2
mixin: 2
https://ideone.com/AGGbwj
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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