Converting member variables to strings with using reflection from base class

[kerdemdemir via Digitalmars-d-learn]

I want to make a logging function for member variables by using 
reflection.

import std.stdio;
class D : B
{
    override void foo() {
        a  = 4.0;
        b  = 3.0;
    }
    double a;
    double b;
}

class B
{
    void Log()
    {
        auto a = [__traits(derivedMembers, D)];
        foreach(memberName; a) {
            // Somehow write only member variables with their 
names
            // Result should be : a = 4.0, b = 3.0
        }
    }

    void foo()
    {
    }
}

void main()
{
     auto b = new D;
     b.Log();
}

As I wrote in the comments I want to see member variable's name 
and its value.
What is the best way to achieve that?

Erdem