C#

public class Xot
{
    #region Static
    static Xot()
    {
    }
    private static readonly Xot instance = new Xot();

    public static Xot Instance { get { return instance; } }
    #endregion


    private Dictionary<int,> calls;
    private bool initialised = false;
    private Timer waitTimer;
    
    private Xot()
    {
        calls = new Dictionary<int,>();
        waitTimer = new Timer(this.ReadEvents, null, Timeout.Infinite, Timeout.Infinite);

        // Initialise the library, no other thread should be able to call 
       //Instance.CreateCall until this has completed
       Console.WriteLine("Initialising Xot");
        if (!this.initialised)
        {
            lock (Xot.Instance) // this doesnt seem to do it nor does lock(this)
            {
                int rc = X25.HsX25DllInit(
                               "10.80.105.102",
                               0,
                               1024,
                               2,
                               1,
                               4095,
                               1);
                if (rc == X25.HSX25DLL_RC_OK)
                {
                    initialised = true;
                    this.waitTimer.Change(0, 15);
                }
                else
                {
                    throw new Exception(String.Format("Failed to initialised Xot. RC={0}", rc));
                }
            }
        }
    }   
   
     // Will a finaliser work here?
    ~Xot()
    {
        if (this.initialised)
        {
            Console.WriteLine("Shutting Down Xot");
            int rc = X25.HsX25DllShutDown(0);
            if (rc != X25.HSX25DLL_RC_OK)
            {
                throw new Exception(String.Format("Failed to shut down X25 [RC={0}]", rc));
            }
            this.waitTimer.Change(Timeout.Infinite, Timeout.Infinite);
            this.initialised = false;
        }
    }

    private void CheckInit()
    {
        if (!this.initialised)
            throw new InvalidOperationException("Not initialised");
    }

    public XotCall CreateCall()
    {
        this.CheckInit();
        XotCall call = new XotCall(this);
        return call;
    }
}