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  1. #include <iostream>
  2.  
  3. template <typename T>
  4. class A
  5. {
  6. public:
  7.     A(T t) : mT(t) {}
  8.     virtual ~A() {}
  9.     virtual void doThings() = 0;
  10. protected:
  11.     T mT;
  12. };
  13.  
  14. template <typename T, typename A = A<T>>
  15. class B : public A
  16. {
  17. public:
  18.     B(T t) : A(t) {}
  19.     virtual ~B() {}
  20.     virtual void doThings() { std::cout << "B" << std::endl; std::cout << A::mT << std::endl; }
  21. };
  22.  
  23. template <typename T, typename A = A<T>>
  24. class C : public A
  25. {
  26. public:
  27.     C(T t) : A(t) {}
  28.     virtual ~C() {}
  29.     virtual void doThings() { std::cout << "C" << std::endl; std::cout << A::mT << std::endl;}
  30. };
  31.  
  32. template <typename... T>
  33. void ignore(T&&... t)
  34. {
  35. }
  36.  
  37. template <typename T, typename ...Args>
  38. class ChildGenerator : public Args...
  39. {
  40. public:
  41.     ChildGenerator(T t) : Args(t)... {}
  42.  
  43.     // The unpacking of the variadic template does not work here.
  44.     // Do I need to make it recursive somehow? How can I do that without having to instantiate new classes B and C?
  45.     void doThings() override { ((Args::doThings()) , ...);}
  46. };
  47.  
  48. int main()
  49. {
  50.     using B = B<double>;
  51.     using C = C<double>;
  52.     B c1(0.0);
  53.     C c2(1.0);
  54.     ChildGenerator<double, B, C> c3(2.0);
  55.     c1.doThings();
  56.     c2.doThings();
  57.     c3.doThings();
  58.  }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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B
0
C
1
B
2
C
2
https://ideone.com/rzFeok
language:
C++14 (clang 8.0)
created:
8 years ago
visibility:
public

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