boost - enable_if and constructors -


whats wrong this?

i thought should work when using enable if???

help??

shouldnt second constructor excluded?

#include <iostream> #include <boost/type_traits.hpp> #include <boost/utility/enable_if.hpp> template<class t> class integral_holder{ public: integral_holder(t value_, typename boost::enable_if_c< boost::is_integral<t>::value>::type* ignore = 0) : value(value_){ std::cout << "integral" << std::endl; } integral_holder(t value_, typename boost::enable_if_c< boost::is_floating_point<t>::value>::type* ignore = 0) : value(floor(value_)){ std::cout << "floating point" << std::endl; } private: t value;

};

int main(int argc, const char * argv[]) { integral_holder<int> a(22); return 0; }

when class generated out of class template , in process declarations of constructors instantiated (not theiry body, "signature"), enable_if type invalid , compiler error.

you need make enable_if type depend on template parameter of constructor (make function template). goal works because invalid type formed during deducing function template parameter type when use constructor trigger sfinae case.


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