Re: [boost] Workaround for compiler bugs

7 Dec 2010


      On 12/6/2010 5:00 PM, Stephan T. Lavavej wrote:
...
[Edward Diener]
...
https://connect.microsoft.com/VisualStudio/feedback/details/624757/incorrect...
Is this sufficient for your purposes? (Requires VC10.)
C:\Temp>type meow.cpp
#include<type_traits>
#define DEFINE_HAS_MEMBER(NAME)                                             \
template<typename T>  class has_member_ ## NAME {                           \
private:                                                                    \
     template<typename U>  static std::true_type helper(decltype(&U::NAME)); \
     template<typename U>  static std::false_type helper(...);               \
public:                                                                     \
     typedef decltype(helper<T>(nullptr)) type;                              \
     static const bool value = type::value;                                  \
};
You missed the fact in the attachment that the T passed in must be the 
full signature of a pointer to data member, as in 'Gipf Dvonn::*' in 
your first example below. Otherwise if you can get it to work in VC++, I 
would be most appreciative, although I do not know if I want to use the 
C++0x 'decltype' feature since the library theoretically needs to work 
with C++03 standard compliant compilers.
...
DEFINE_HAS_MEMBER(cMem)
struct Gipf { };
struct Dvonn {
     Gipf cMem;
};
struct Tzaar {
     bool cMem;
};
struct Yinsh {
     int Zertz;
};
int main() {
     static_assert(has_member_cMem<Dvonn>::value, "Dvonn");
     static_assert(has_member_cMem<Tzaar>::value, "Tzaar");
     static_assert(!has_member_cMem<Yinsh>::value, "Yinsh");
}
C:\Temp>cl /EHsc /nologo /W4 meow.cpp
meow.cpp
C:\Temp>