Inserting a variadic argument list into a vector?

Question

Forgive me if this has been answered already, as I couldn't find it...

Basically I have an object that needs to take a variadic argument list in it's constructor and store the arguments in a vector. How do I initialize a vector from a the arguments of a variadic constructor?

class GenericNode { public:     GenericNode(GenericNode*... inputs) {             /* Something like... */         // inputs_.push_back(inputs)...; } private:     std::vector<GenericNode*> inputs_; }; 

Answer 1

The best thing would be to use an initializer list

#include <initializer_list> #include <vector> class GenericNode { public:     GenericNode(std::initializer_list<GenericNode*> inputs)          :inputs_(inputs) {} //well that's easy private:     std::vector<GenericNode*> inputs_; }; int main() {     GenericNode* ptr;     GenericNode node{ptr, ptr, ptr, ptr}; } //compilation at http://stacked-crooked.com/view?id=88ebac6a4490915fc4bc608765ba2b6c 

The closest to what you already have, using C++11 is to use the vector's initializer_list:

    template<class ...Ts>     GenericNode(Ts... inputs)          :inputs_{inputs...} {} //well that's easy too     //compilation at http://stacked-crooked.com/view?id=2f7514b33401c51d33677bbff358f8ae 

And here's a C++11 version with no initializer_lists at all. It's ugly, and complicated, and requires features missing from many compilers. Use the initializer list

template<class T> using Alias = T;  class GenericNode { public:     template<class ...Ts>     GenericNode(Ts... inputs) { //SFINAE might be appropriate          using ptr = GenericNode*;          Alias<char[]>{( //first part of magic unpacker              inputs_.push_back(ptr(inputs))              ,'0')...,'0'}; //second part of magic unpacker     } private:     std::vector<GenericNode*> inputs_; }; int main() {     GenericNode* ptr;     GenericNode node(ptr, ptr, ptr, ptr); } //compilation at http://stacked-crooked.com/view?id=57c533692166fb222adf5f837891e1f9 //thanks to R. Martinho Fernandes for helping me get it to compile 

Unrelated to everything, I don't know if those are owning pointers or not. If they are, use std::unique_ptr instead.