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  1. class Base {
  2. public:
  3.  
  4.     template<typename Outer>
  5.     class Thing {
  6.     public:
  7.         Thing(Base& b) : _b(b) {};
  8.  
  9.         Thing& operator+= (const Thing p) { _b.add(*this, p); return *this; };
  10.  
  11.         int k;
  12.     protected:
  13.         Outer& _b;
  14.     };
  15.  
  16. 	template<typename Outer>
  17.     void add(Thing<Outer> &d, const Thing<Outer> s) { d.k += s.k; }
  18. };
  19.  
  20. template <class... Interfaces>
  21. class Extensible : virtual public Base, virtual public Interfaces... {
  22.  
  23.     class Thing : virtual public Base::Thing<Base>, virtual public Interfaces::template Thing<Base>... {
  24.  
  25.     };
  26. };
  27.  
  28. class SomeInterface : Base {
  29.     void multiply(Thing<SomeInterface> &d, const Thing<SomeInterface> s) { d.k *= s.k; }
  30.  
  31.     class Thing : public Base::Thing<SomeInterface> {
  32.         Thing& operator*= (const Thing p) {
  33.             _b.multiply(*this, p); return *this; // <-- won't work of course
  34.         };
  35.  
  36.     };
  37.  
  38. };
  39.  
  40. int main() {
  41.     Extensible<SomeInterface> a;
  42.     return 0;
  43. }
  44.  
Success #stdin #stdout 0s 3336KB
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https://ideone.com/KhLyfj
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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