[C++]std::initializer_list

#include <initializer_list>
#include <vector>
#include <iostream>
 
class EvenSequence
{
    public:
        EvenSequence(std::initializer_list<double> args)
        {
            if(args.size() % 2 != 0){
                throw std::invalid_argument("initializer_list should "
                        "contain even number of elements");
            }
            mSequence.reserve(args.size());
            for(auto value : args) {
                mSequence.push_back(value);
            }
        }
        void dump() const
        {
            for(auto value : mSequence) {
                std::cout << value << ", ";
            }
            std::cout << std::endl;
        }
    private:
        std::vector<double> mSequence;
};
 
 
int main()
{
    EvenSequence p1{1.0, 2.0,3.0,4.0};
    p1.dump();
    return 0;
}