class A : ICloneable
{
    int id;
    string name;
    static Random random = new Random();
    public A(string name) { this.id = random.Next(); this.name = "name #" + this.id; }
    pulbic object Clone() { return new A(id, name); }
    private A(int id, string name) { this.id = id; this.name = name; }
}

class Axis
{
    public string Name { get; }
    public Vector Direction { get; }
    private Axis(string name, Vector direction) { Name = name; Direction = direction; }
    static public readonly Axis X = new Axis("X", new Vector(1, 0, 0);
    static public readonly Axis Y = new Axis("Y", new Vector(0, 1, 0);
    static public readonly Axis Z = new Axis("Z", new Vector(0, 0, 1);
}

class Point
{
    public double X { get; }
    public double Y { get; }
    public double R { get; }
    public double Phi { get; }
    private Point(double x, double y, double r, double phi)
    {
        X = x; Y = y; R = r; Phi = phi;
    }
    public Point FromCartesian(double x, double y)
    {
        double r = Math.Sqrt(x * x + y * y);
        double phi = Math.Atan2(y, x);
        return new Point(x, y, r, phi);
    }
    public Point FromPolar(double r, double phi)
    {
        double x = r * Math.Cos(phi);
        double yx = r * Math.Sin(phi);
        return new Point(x, y, r, phi);
    }
}

public class MyClass {
    private static Dictionary<object, MyClass> cache =
        new Dictionary<object, MyClass>();

    private MyClass() {
    }

    public static MyClass GetInstance(object data) {
        MyClass output;

        if (!cache.TryGetValue(data, out output))
            cache.Add(data, output = new MyClass());

        return output;
    }
}

public abstract class BaseClass {
    private BaseClass() {
        // здесь какая-то базовая инициализация
        // этот конструктор должен быть вызван из конструкторов дочерних классов
    }

    public class SubClass1 : BaseClass {
        public SubClass1() : base() { }
    }

    public class SubClass2 : BaseClass {
        public SubClass2() : base() { }
    }
}