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  1.     #include <stdio.h>
  2.     #include <type_traits>
  3.     #include <typeinfo>
  4.  
  5.     struct Base {};
  6.     struct OfBase: public Base {};
  7.     struct NotBase {};
  8.     template <typename T1, typename T2, typename = void>
  9.     struct select_base
  10.     {
  11.         typedef T1 type;
  12.     };
  13.     template <typename T1, typename T2>
  14.     struct select_base<T1, T2, typename std::enable_if<
  15.         std::is_base_of<Base, T2>::value, T2>::type>
  16.     {
  17.         typedef T2 type;
  18.     };
  19.     int main()
  20.     {
  21.        printf("Expected OfBase: %s\n", typeid(typename select_base<NotBase, OfBase>::type).name());
  22.        printf("Expected OfBase: %s\n", typeid(typename select_base<OfBase, NotBase>::type).name());
  23.        return 0;
  24.     }
Success #stdin #stdout 0s 2884KB
comments (?)
stdin 
Standard input is empty
stdout 
Expected OfBase: 7NotBase
Expected OfBase: 6OfBase
https://ideone.com/EnVT8
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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