Sinlgeton<WTF>

singleton.cs

    public static class Singleton<T> where T : class
    {
        static volatile T _instance;
        static object _lock = new object();

        static Singleton()
        {
        }

        public static T Instance
        {
            get
            {
                if (_instance == null)
                    lock (_lock)
                    {
                        if (_instance == null)
                        {
                            ConstructorInfo constructor = null;

                            // Binding flags exclude public constructors.
                            constructor = typeof(T).GetConstructor(BindingFlags.Instance |
                                          BindingFlags.NonPublic, null, new Type[0], null);


                            if (constructor == null || constructor.IsAssembly)
                                // Also exclude internal constructors.
                                throw new InvalidOperationException(string.Format("A private or " +
                                      "protected constructor is missing for '{0}'.", typeof(T).Name));
                            _instance = (T)constructor.Invoke(null);
                        }
                    }

                return _instance;
            }
        }
    }