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  1. #include <cstdint>
  2.  
  3. #define DEFINE_HAS_SIGNATURE(traitsName, funcName, signature)               \
  4.     template <typename U>                                                   \
  5.     class traitsName                                                        \
  6.     {                                                                       \
  7.     private:                                                                \
  8.         template<typename T, T> struct helper;                              \
  9.         template<typename T>                                                \
  10.         static std::uint8_t check(helper<signature, &funcName>*);           \
  11.         template<typename T> static std::uint16_t check(...);               \
  12.     public:                                                                 \
  13.         static                                                              \
  14.         constexpr bool value = sizeof(check<U>(0)) == sizeof(std::uint8_t); \
  15.     }
  16.  
  17. DEFINE_HAS_SIGNATURE(has_foo, T::foo, void (*)(void));
  18.  
  19. struct StaticFoo { static void foo(); };
  20. struct NormalFoo { void foo(); };
  21. struct NoFoo {};
  22.  
  23. static_assert(has_foo<StaticFoo>::value, "Unexpected value");
  24. static_assert(!has_foo<NormalFoo>::value, "Unexpected value");
  25. static_assert(!has_foo<NoFoo>::value, "Unexpected value");
  26.  
  27. int main()
  28. {
  29.     return 0;
  30. }
  31.  
Success #stdin #stdout 0s 3336KB
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https://ideone.com/nDlFUE
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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