c++ - Template inheritance and a base member variable -

i weird error when trying use template inheritance. code:

template <class t> class { public:     int {2};     a(){}; };  template <class t> class b : public a<t> {     public:     b(): a<t>() {};     void test(){    std::cout << "testing... " << << std::endl;   }; }; 

and error:

error: use of undeclared identifier 'a'; did mean 'std::uniform_int_distribution<long>::a'?     void test(){    std::cout << "testing... " << << std::endl;   } 

and in case affect use these flags:

-wall -g -std=c++11 

i don't know wrong since same code pure classes without templating works fine.

i don't know wrong since same code pure classes without templating works fine.

this because base class (class template a) not nondependent base class, type can't determined without knowing template arguments. , a nondependent name. nondependent names not looked in dependent base classes.

to correct code, make name a dependent, dependent names can looked @ time of instantiation, @ time exact base specialization must explored , known.

you could

void test() { std::cout << "testing... " << this->a << std::endl; }; 

or

void test() { std::cout << "testing... " << a<t>::a << std::endl; }; 

or

void test() {      using a<t>::a;     std::cout << "testing... " << << std::endl;  };