c++ - Defining a variadic template type with unknown argument list as std::map value type -

i not sure if possible @ trying achieve past 3 hours without sense-making approach.

i have variadic template this:

template<typename... ts> class xunit_test_item { public:     template<typename f, typename... args>     xunit_test_item(const std::string& name, f&& func, args&&... args)     : m_name(name)     , m_f(std::forward<f>(func))     , m_args(std::forward<args>(args)...)     {     }      // ...  private:     const std::string m_name;     std::function<void (ts...) > m_f;     std::tuple<ts...> m_args; }; 

above template wraps test item holder of functor passed arguments along string name item.

objects of type have stored std::map value type. handled in class contains std::map container member, registration method add xunit_test_item items , run method, iterates on map , executes stored xunit_test_item stored functions.

the class looks this:

class unit_test {      // define map type of xunit_test_items     template<typename ...ts>     using testitem_map_t = std::map<size_t, xunit_test_item<ts...>>;  public:     unit_test() = delete;     unit_test(const std::string& group_name)     : m_tm()     , m_group_name(group_name)     , m_test_id(0)     {      }     // register functor item     template<typename f, typename ...args>     void add_test(const std::string& name, f&& fun, args&& ...args) {         m_tm.emplace(++m_test_id, xunit_test_item<args...>(             name, std::forward<f>(fun), std::forward<args>(args)...));     }      void run()      {         // ...          (auto& t : m_tm) {             // ...             t.second->run();             // ...         }     }  private:     testitem_map_t m_tm; // <-- compiler correctly reports error     std::string m_group_name;     size_t m_test_id; }; 

the problem have find right syntax / different approach define xunit_test_item value type of m_tm map member. above code not compiling - without doubt - have specify argument list m_tm member type testitem_map_t. have no idea how define type , declare correctly m_tm member. argument list unknown @ point. perhaps above classes have design issue, wonder if there more or less simple way achieve this. may fail see simple solution.

would happy learn , suggestion. in advance!

update

fresh day, fresh try , cup of coffee ...

i refactored body of add_test method using 2-level lambda , seems work far. test functions (the actual test cases) can add lambdas, function pointers arbitrary or no arguments @ all.

i don't know if best solution, or if can coded in better way, maybe wants comment on topic. reason why not enter answer. hope initial question maybe learn c++14 sugar solution ... if possible.

this first tested version ...

template<typename f, typename ...args> void add_test(const std::string& name, f&& fun, args&& ...args) {     std::function<void(args...)> fun_xargs =         [name, fun](auto&&... args) {             std::cout << "  inner lambda\n";             auto x = xunit_test_item<args...>(name, fun, std::forward<args>(args)...);             x.run();         };      std::function<void()> fun_void =          [=] {             std::cout << "outer lambda\n";             fun_xargs(args...);         };      m_tm.emplace(++m_test_id, fun_void); } 

it seems need:

class unit_test { public:     unit_test() = delete;     unit_test(const std::string& group_name)     : m_tm(), m_group_name(group_name)     {      }      // register functor item     void add_test(const std::string& name, std::function<void()> f) {         m_tm.emplace(name, std::move(f));     }      void run()      {         // ...         (const auto& t : m_tm) {             // ...             t.second->run();             // ...         }     }  private:     std::map<std::string, std::function<void()>> m_tm;     std::string m_group_name; };