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  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. template <typename T>
  6. class Base
  7. {
  8.     public:
  9.         T* t;
  10.         void b() {}
  11. };
  12.  
  13. class D1:
  14.         public Base<D1>
  15. {
  16.     public:
  17.         int d1;
  18. };
  19.  
  20. class D2:
  21.         public D1
  22. {
  23.     public:
  24.         int d2;
  25. };
  26.  
  27. template<template<typename> class Base, typename T>
  28. struct IsAnyPublicBaseOf
  29. {
  30.   typedef char (&yes)[2];
  31.  
  32.   template<typename X>
  33.   static yes Check (Base<X>*);
  34.   static char Check (...);
  35.  
  36.   static const bool value = (sizeof(Check((T*)0)) == sizeof(yes));
  37. };
  38.  
  39. template<bool> struct Bool;
  40. template <typename T, typename = Bool<true> >
  41. class Selector
  42. {
  43. public:
  44.   template <typename U>
  45.   void a(U& u)
  46.   {
  47.     cout << "a(U&)" << endl;
  48.   }
  49. };
  50.  
  51. template<typename T>
  52. class Selector<T,Bool<IsAnyPublicBaseOf<Base,T>::value> >
  53. {
  54. public:
  55.   template <typename U>
  56.   void a(Base<U>& base)
  57.   {
  58.     cout << "a(Base<U>&)" << endl;
  59.     base.b();
  60.   }
  61. };
  62.  
  63.  
  64. int main()
  65. {
  66.     D2 derivated;
  67.     Selector<D2> s;
  68.     s.a(derivated);
  69.     return 0;
  70. }
  71.  
Success #stdin #stdout 0.02s 2724KB
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a(Base<U>&)
https://ideone.com/khaPi7
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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