Calling another constructor when constructing an object with const members

Question

I have a class with const members, and one constructor which calls another constructor with extra values filled in. Normally I could use a colon initializer for

Answer 1

How about making a helper function:

class A
{
    static int initializor(int b) { int n; myfunc(b, &n); return n; }
public:
    explicit A(int b_) : b(b_), c(initializor(b_)) { }
    A(int b_, int c_)  : b(b_), c(c_)              { }

    // ... as before ...
};