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  1.  
  2. #include <iostream>
  3.  
  4.  
  5. template<typename T>
  6. class Enforcer: public T
  7. {
  8. public:
  9.     template<typename... Args>
  10.     Enforcer(Args&&... arg): T(std::forward<Args>(arg)...)
  11.     {
  12.  
  13.     }
  14.  
  15.     void init() override
  16.     {
  17.         T::init();
  18.         T::BaseClass::init();
  19.     }
  20. };
  21.  
  22. class Base
  23. {
  24. public:
  25.     virtual void init() = 0;
  26. private:
  27.     bool initialized = false;
  28. };
  29.  
  30. void Base::init() 
  31. {
  32.     std::cout << "Called from base!\n";
  33.     initialized = true;
  34. }
  35.  
  36. class Derived: public Base
  37. {
  38.     friend class Enforcer<Derived>;
  39. public:
  40.     void init() override
  41.     {
  42.         std::cout << "Called from derived!\n";
  43.     }
  44. private:
  45.     Derived()
  46.     {
  47.     }
  48. private:
  49.     using BaseClass = Base;
  50. private:
  51.     bool initialized = false;
  52. };
  53.  
  54. int main()
  55. {
  56.     Enforcer<Derived> d;
  57.     d.init();
  58. }
  59.  
  60.  
Success #stdin #stdout 0s 3460KB
comments (?)
stdin 
Standard input is empty
stdout 
Called from derived!
Called from base!
https://ideone.com/aaf9cj
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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