Singleton

/*
sealed class  Singleton {
    private static readonly Singleton instance = new Singleton();
    private Singleton() {
    }
    static Singleton() {
    }
    public static Singleton Instance {
        get {
            return instance;
        }
    }
}
*/

public class Singleton<T> where T : class, new()
{
    private static readonly object syncLock = new object();
    private static T instance;

    protected Singleton()
    {
    }

    public static T Instance
    {
        get
        {
            if (instance == null)
            {
                lock (syncLock)
                {
                    if (instance == null)
                    {
                        instance = new T();
                    }
                }
            }
            return instance;
        }
    }
}