c++ - static_assert to check value in non-template class's template constructor -

so, i'm looking way cause compile-time error if value used in declaring object equal value (don't wish use c's assert macro).

yes, know why problem occurs... compiler quite clear when he/she complained expression did not evaluate constant.

i don't want make entire class template. there little miracle workaround i'm missing?

#include <iostream>  class test { private:     template<class t, class t2>     using both_int = std::enable_if_t<std::is_integral<t>::value && std::is_integral<t2>::value>; private:     int _a, _b; public:      template<class t, class t2 = t, class = both_int<t, t2>>     constexpr test(const t &a, const t2 &b = 1)         : _a(a), _b(b)     {         static_assert(b != 0, "division zero!");     } };  int main() {     test obj(1, 0); //error      test obj2(0, 1); //ok      std::cin.get(); } 

you can this:

struct test { private:   constexpr test(int a, int b) {} public:   template<int b>   static test construct(int a) {     static_assert(b != 0, "not 0 failed");     return test(a, b);   }      };  int main() {    test foo = test::construct<1>(1);    test foo = test::construct<0>(1);//compile error } 

you need static constructor, because of there no way specify parameters of template constructor, see c++ template constructor