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  1. #include <type_traits>
  2. #include <string>
  3. #include <iostream>
  4. #include <functional>
  5.  
  6. // Данные
  7. struct Base
  8. {};
  9.  
  10. struct A : Base
  11. {
  12.     std::string name = "A";
  13. };
  14.  
  15. struct B : Base
  16. {
  17.     std::string name = "B";
  18. };
  19. struct Meta
  20. {
  21.     public:
  22.     template< typename T >
  23.     explicit Meta( const T& data )
  24.         : _data{data}
  25.         , getName{
  26.             [](const Base& base) {
  27.                 return static_cast<const T&>(base).name;
  28.             }
  29.         }
  30.     {
  31.        static_assert(std::is_base_of<Base, T>::value, "");
  32.     }
  33.  
  34.     std::string name() const
  35.     {
  36.         return "Name is: " + getName(_data);
  37.     }
  38.  
  39. private:
  40.     const Base& _data;
  41.     std::function<std::string(const Base&)> getName;
  42. };
  43.  
  44. template< typename T >
  45. Meta Wrap( const T& data )
  46. {
  47.     return Meta{ data };
  48. }
  49.  
  50.  
  51. int main()
  52. {
  53.     const A a{};
  54.     const B b{};
  55.     const auto wa = Wrap( a );
  56.     const auto wb = Wrap( b );
  57.  
  58.     std::cout << wa.name() << "\n";
  59.     std::cout << wb.name() << "\n";
  60.  
  61.     for ( const auto& meta : { wa, wb } )
  62.         std::cout << meta.name() << "\n";
  63.  
  64.     return 0;
  65. }
Success #stdin #stdout 0s 15240KB
comments (?)
stdin 
Standard input is empty
stdout 
Name is: A
Name is: B
Name is: A
Name is: B
https://ideone.com/jJkd8N
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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