c++ - uniform initialization with variadic templates -

i have pod chparam , it's parameter in variadic template function set. i'd pass function arguments(constructor parameters) in curly braces p.set({ param::d, 1000.f }, { param::p, 2000.f }). , thought constructor called implicitly , chparam objects created. it's impossible, should explicitly create object a.set(chparam{ param::d, 1000.f }, chparam{ param::p, 2000.f });

is possible somehow use variant p.set({ param::d, 1000.f }, { param::p, 2000.f })?

#include <iostream> using namespace std;  using float = float;  enum class param : size_t {     d = 0,     p }; struct chparam {     param tag_;     float value_; }; class pipecalcparams { private:     float d_, p_; public:     pipecalcparams() : d_(0), p_(0) {}     pipecalcparams& set_d(float d) { d_ = d; return *this; }     pipecalcparams& set_p(float p) { p_ = p; return *this; }       template <typename... args>     pipecalcparams& set(const chparam& p, args&&... args) {         set(p);         return set(args...);     }      pipecalcparams& set(const chparam& p)     {         switch (p.tag_)         {         case param::d:             set_d(p.value_);             break;         case param::p:             set_p(p.value_);             break;         }          return *this;     }  };  int main() {     pipecalcparams a;     a.set(chparam{ param::d, 1000.f }, chparam{ param::p, 2000.f });//ok      pipecalcparams p;     p.set({ param::d, 1000.f }, { param::p, 2000.f });//error: no matching function call 'pipecalcparams::set(<brace-enclosed initializer list>, <brace-enclosed initializer list>)' p.set({ param::d, 1000.f }, { param::p, 2000.f });     return 0; } 

it not directly possible use

{ param::d, 1000.f } 

as function parameter when needs deduced. reason braced initializer list has no type. since not have type, type cannot deduced compiler. have along. can did , specify type like

chparam{ param:d, 1000.f } 

or can specify type of object expecting. if want variable numbers of same types std::intializer_list work. allows compiler construct elements individual braced initializer lists. using code like

pipecalcparams& set(std::initializer_list<chparam> args) 

and when call use

p.set({{ param::d, 1000.f }, { param::p, 2000.f }}) 

do note set of curly braces used. outermost set declares std::intializer_list , each inner set declares each chparam in list.