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  1. #include <iostream>
  2. #include <memory>
  3.  
  4. template <int T>
  5. class E
  6. {
  7. public:
  8.     template <typename ... ArgTypes>
  9.     class Base
  10.     {
  11.     public:
  12.         void operator()(ArgTypes ... args)
  13.         {
  14.             On(nullptr, args...);
  15.         }
  16.         virtual void On(Base<ArgTypes...>*, ArgTypes...) = 0;
  17.     };
  18. };
  19.  
  20. class A : public E<0>::Base<int>
  21.         , public E<1>::Base<int>
  22. {
  23. public:
  24.  
  25.     void On(E<0>::Base<int>*, int val) override
  26.     {
  27.         std::cout << "E<0>::Base<int> called: " << val << std::endl;
  28.     }  
  29.  
  30.     void On(E<1>::Base<int>*, int val) override
  31.     {
  32.         std::cout << "E<1>::Base<int> called: " << val*val << std::endl;
  33.     }  
  34. };
  35.  
  36. int main() {
  37. 	std::shared_ptr<A> a = std::make_shared<A>();
  38. 	a->E<0>::Base<int>::operator()(2);
  39. 	a->E<1>::Base<int>::operator()(2);
  40.  
  41. 	return 0;
  42. }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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E<0>::Base<int> called: 2
E<1>::Base<int> called: 4
https://ideone.com/FopomV
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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