不能被继承的类

 1 
 2  namespace 不能被继承的类{
 3     template<typename T>
 4     class un_base;
 5     template<typename T>
 6     class un_base_I:public T{
 7         friend un_base<T>;
 8     private:
 9         un_base_I(){}
10     };
11     template<typename T>
12     class un_base:virtual public un_base_I<T>{
13     public:
14         un_base(){}
15     };
16 
17     class my_class{public: int a,b,c;};
18 
19     class my_err_test:public un_base<my_class>{};//ERROR
20      void main() {
21         un_base<my_class> oc;//OK
22      }
23 }