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  1. #include <iostream>
  2. #include <memory>
  3.  
  4. class D1;
  5. class D2;
  6. class D3;
  7.  
  8. class Base {
  9. public:
  10.     void func(const D1& obj) const
  11.     {
  12.         return this->applyFunc(obj);
  13.     }
  14.  
  15.     void func(const D2& obj) const
  16.     {
  17.         return this->applyFunc(obj);
  18.     }
  19.  
  20.     void func(const D3& obj) const
  21.     {
  22.         return this->applyFunc(obj);
  23.     }
  24.  
  25. private:
  26.     virtual void applyFunc(const D1& obj) const = 0;
  27.     virtual void applyFunc(const D2& obj) const = 0;
  28.     virtual void applyFunc(const D3& obj) const = 0;
  29. };
  30.  
  31. class D1 : public Base {
  32. private:
  33.     // Inherited via Base
  34.     virtual void applyFunc(const D1& obj) const override
  35.     {
  36.         std::cout << "D1 & D2" << std::endl;
  37.         return;
  38.     }
  39.     virtual void applyFunc(const D2& obj) const override
  40.     {
  41.         std::cout << "D2 & D2" << std::endl;
  42.         return;
  43.     }
  44.     virtual void applyFunc(const D3& obj) const override
  45.     {
  46.         std::cout << "D3 & D2" << std::endl;
  47.         return;
  48.     }
  49. };
  50.  
  51. class D2 : public Base {
  52. private:
  53.     // Inherited via Base
  54.     virtual void applyFunc(const D1& obj) const override
  55.     {
  56.         std::cout << "D2 call D1" << std::endl;
  57.         return;
  58.     }
  59.     virtual void applyFunc(const D2& obj) const override
  60.     {
  61.         std::cout << "D2 call D2" << std::endl;
  62.         return;
  63.     }
  64.     virtual void applyFunc(const D3& obj) const override
  65.     {
  66.         std::cout << "D2 call D3" << std::endl;
  67.         return;
  68.     }
  69. };
  70.  
  71. class D3 : public Base {
  72. private:
  73.     void printDontCallMe() const
  74.     {
  75.         std::cout << "Don't call me." << std::endl;
  76.         return;
  77.     }
  78.  
  79. private:
  80.     // Inherited via Base
  81.     virtual void applyFunc(const D1& obj) const override
  82.     {
  83.         this->printDontCallMe();
  84.         return;
  85.     }
  86.     virtual void applyFunc(const D2& obj) const override
  87.     {
  88.         this->printDontCallMe();
  89.         return;
  90.     }
  91.     virtual void applyFunc(const D3& obj) const override
  92.     {
  93.         this->printDontCallMe();
  94.         return;
  95.     }
  96. };
  97.  
  98. int main()
  99. {
  100.     const auto d1 = std::make_unique<const D1>();
  101.     const auto d2 = std::make_unique<const D2>();
  102.     const auto d3 = std::make_unique<const D3>();
  103.     d1->func(*d1);    d1->func(*d2);    d1->func(*d3);
  104.     d2->func(*d1);    d2->func(*d2);    d2->func(*d3);
  105.     d3->func(*d1);    d3->func(*d2);    d3->func(*d3);
  106.     return 0;
  107. }
Success #stdin #stdout 0s 3472KB
comments (?)
stdin
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Standard input is empty
stdout
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D1 & D2
D2 & D2
D3 & D2
D2 call D1
D2 call D2
D2 call D3
Don't call me.
Don't call me.
Don't call me.
https://ideone.com/46KJPS
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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