CODEWITHSUNDEEP
c++c++11
Ferenc Deak
Ferenc Deak

Reputation: 35438

Implementation of std::is_class

I was wondering how the std::is_class (http://www.cplusplus.com/reference/type_traits/is_class/) is actually implemented. I looked at /usr/include/c++/4.8/tr1/type_traits but it seems that the only thing which is there is:

/// is_class
template<typename _Tp>
  struct is_class
  : public integral_constant<bool, __is_class(_Tp)>
  { };

and the definition of __is_class is not to be found anywhere (or I just did not look deep enough). anyway I would be happy if someone could point out to me where to look for this (and also the other is_*** from the std namespace)

Upvotes: 4

Views: 972

Answers (1)

Maxim Egorushkin
Maxim Egorushkin

Reputation: 136415

__is_class is a C++ extension provided by gcc compiler. See gcc type traits.

The C++ front end implements syntactic extensions that allow compile-time determination of various characteristics of a type (or of a pair of types).

Upvotes: 3

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