tupleof for inherited classes.

[mrdarksys]

[Problem]
How can I use enumFields() function of Engine class for enumerate 
all fields of inherited classes?
I want to do without templates if possibly.
Code [example]:
//============
import std.stdio;

class Engine
  {
    public:
      int publicField;

      void enumFields()
        {
          writeln("Engine prints:");
          foreach(ref field; this.tupleof)
            writeln(field);
        }

    private:
      bool privateField;

    protected:
      string protectedField = "s";
  }

class Some : Engine
  {
    public:
      int oneMoreField = 11;

      void enumFields2()
        {
          writeln("Some prints:");
          foreach(field; this.tupleof)
            writeln(field);
        }

    protected:
      string protectedField = "o";
  }

int main()
  {
    auto objE = new Engine();
    auto objS = new Some();

    objE.enumFields();

    objS.publicField = 4;

    objS.enumFields();

    objS.enumFields2();

    return 0;
  }
//==============

[Actual] output is:
//==============
Engine prints:
0
false
s
Engine prints:
4
false
s
Some prints:
11
o
//==============

[Expected] output is:
//==============
Engine prints:
0
false
s
Engine prints:
4
false
o
11
Some prints:
4
false
o
11
//==============