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  1. // A simple example using type-erasure.
  2.  
  3. #include <iostream>
  4. #include <vector>
  5. #include <memory>
  6.  
  7. class Example {
  8.     struct _Concept {
  9.         virtual ~_Concept() = default;
  10.         virtual const char* f() const = 0;
  11.     };
  12.  
  13.     template<typename T>
  14.     struct _Model : _Concept {
  15.         _Model(T* p)
  16.         : m_p(p)
  17.         {}
  18.         const char* f() const
  19.         { return m_p->f(); }
  20.     private:
  21.         T* m_p;
  22.     };
  23.  
  24.     std::vector<std::unique_ptr<_Concept>> m_items;
  25.  
  26. public:
  27.     template<typename T>
  28.     void add_item(T* p)
  29.     {
  30.         m_items.push_back(std::make_unique<_Model<T>>(p));
  31.     }
  32.  
  33.     void process_items()
  34.     {
  35.         for (const auto& x : m_items)
  36.             std::cout << x->f() << std::endl;
  37.     }
  38. };
  39.  
  40. // Use.
  41.  
  42. struct A {
  43.     const char* f()
  44.     { return "A::f"; }
  45. };
  46.  
  47. struct B {
  48.     const char* f()
  49.     { return "B::f"; }
  50. };
  51.  
  52. int main()
  53. {
  54.     Example x;
  55.     A a;
  56.     B b;
  57.     x.add_item(&a);
  58.     x.add_item(&b);
  59.     x.process_items();
  60. }
Success #stdin #stdout 0s 5312KB
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Standard input is empty
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A::f
B::f
https://ideone.com/wR3Tbx
language:
C++ (gcc 8.3)
created:
2 hours ago
visibility:
public

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