c++ initialization of const field via initializer-list ":" section

Question

In below code, how can i declare vv to be const: vector<vector<float>> const vv;? Eg. is there any c++0x version that will let me loop in the : ... "initializer-list" section, before the {}?

#include <vector>
using std::vector;

struct ST {
    vector<int> const x; // simple constructor, initializ. via ": x(x)"
    vector<vector<float>> vv; // requieres loop, can be done in ": ..."?
    ST(vector<int> x, std::initializer_list<vector<float>> lv) : x(x) {
        for (auto v : lv) {
            vv.push_back(v);
        }
    }
};

Answer 1

std::vector has a constructor that takes a initializer list, you do not need the loop:

struct ST {
    vector<int> const x;
    vector<vector<float>> const vv;

    ST(vector<int> x, std::initializer_list<vector<float>> lv) :
        x(x),
        vv{lv} 
    {}
};

In case your example is oversimplified and you really need a loop, you can use a static method to initialize const members in the initializer list:

struct ST {
    vector<int> const x;
    vector<vector<float>> const vv;

    ST(vector<int> x, std::initializer_list<vector<float>> lv) :
        x(x),
        vv{create_vector(lv)} 
    {}
    static vector<vector<float>> create_vector(std::initializer_list<float> lv);
};