c++ - Template specialization containers -

i open question code sample:

 template <template <class, class> class container>     class schedule {         public:           schedule& print( std::ostream& os);       private:          container<course*, std::allocator<course*> >  courses;      };       // implement funcion print:       template <template <class, class> class container>      schedule<container>& schedule<container>::print(std::ostream& os){           std::sort(courses.begin(), courses.end(), sor_con());          std::for_each(courses.begin(), courses.end(), printcontainer(os));          return *this;      }       template<>      schedule<std::list>& schedule<std::list>::print(std::ostream& os){           courses.sort(sort_con());          std::for_each(courses.begin(), courses.end(), printcontainer(os));          return *this;      } 

the schedule class contains template classes (std::list / std::vector) only. because print function needs use sort, need use 2 different ways implement this: std::sort std::vector , sort function of list container std::list.

my code works, think created unnecessary code duplication here. there more efficient way solve problem?

you either overload sort function std::vector , std::list respectively:

template<typename t, typename compare> void sort(std::list<t> &list, compare f) {     list.sort(f); }  template<typename t, typename compare> void sort(std::vector<t> &vector, compare f) {     std::sort(vector.begin(), vector.end(), f); } 

or use type_traits , tag_dispatching:

#include <iostream> #include <list> #include <vector> #include <algorithm> #include <functional>  struct vectorlike_tag { }; struct listlike_tag   { };  template <typename c> struct container_traits;  template <typename t, typename a> struct container_traits<std::vector<t, a>> {   typedef vectorlike_tag category; };  template <typename t, typename a> struct container_traits<std::list<t, a>> {   typedef listlike_tag category; };  template <typename container, typename compare> void sort_helper(container& c, compare f, vectorlike_tag) {   std::sort(c.begin(), c.end(), f); }  template <typename container, typename compare> void sort_helper(container& c, compare f, listlike_tag) {   c.sort(f); }  template <typename container, typename compare> void sort_container(container &c, compare f) {   sort_helper(c, f, typename container_traits<container>::category()); }  template<class container> void sort_container(container &c) {   sort_helper(c, std::less<typename container::value_type>(), typename container_traits<container>::category()); }  int main() {   std::vector<int> v{ 4, 3, 7, 8, 9 };   sort_container(v);   (auto e : v) std::cout << e << " ";   std::cout << std::endl;   std::list<int> lst{ 4, 3, 7, 8, 9 };   sort_container(lst, std::greater<int>());   (auto e : lst) std::cout << e << " ";   std::cout << std::endl;   return 0; }