c++ - Creating a namespace using a class defined in another namespace -

i trying out following code whether works or not. need whether done in other way.

 // foo.hpp  namespace traits {    class foo {        public:         typedef std::vector<int>     vec_t;         typedef std::map <int, int>  map_t;    };   };   namespace my_traits = traits::foo;  //i know compile give error "foo" not namespace-name.    // in bar.hpp  using namespace my_traits;  class bar {    private:      vec_t  my_vector;   //  my_traits have foo's members (typedefs)      map_t  my_map;      //  my_traits have foo's members (typedefs)   };       **don't** want following :   using namespace traits;   class bar {     private:       traits::foo::vec_t  my_vector  //  avoid       traits::foo::map_t  my_map     //  avoid   } 

but want put typedefs in class foo , use foo namespace. dont want put typdefs in namespace such.

is possible in c++11 (or in general c++).

thanks

you cannot use class namespace, have use real namespace:

namespace traits {     namespace foo {         typedef std::vector<int>     vec_t;         typedef std::map <int, int>  map_t;     }; };  namespace my_traits = traits::foo; 

using namespace my_traits; class bar { private:     vec_t  my_vector;   //  my_traits have foo's members (typedefs)     map_t  my_map;      //  my_traits have foo's members (typedefs) };