c 2b 2b class constructor variable arguments

1struct A {
2     template<typename ... Args>
3     A(const char * fmt, Args&& ... args) {
4          printf(fmt,std::forward<Args>(args) ...);
5     };
6};
7
8struct B: public A {
9  template<typename ... Args>
10  B(const char * fmt, Args&& ... args) : A(fmt, std::forward<Args>(args) ...) {}
11};
12