private List
     
       visualPlugs = new List
      
       ();        public void Load()        {            DirectoryInfo di = new DirectoryInfo(AppDomain.CurrentDomain.BaseDirectory);            foreach (FileInfo fi in di.GetFiles("VisualControls.*.dll"))            {                Assembly lib = Assembly.LoadFrom(fi.FullName);                foreach (Type t in lib.GetExportedTypes())                {                                 if (t.GetInterface(typeof(IVisualControlsPlug).FullName) != null)                    {                        IVisualControlsPlug plug = (IVisualControlsPlug)Activator.CreateInstance(t);                        InitializePlugin(Env.Current, plug);                    }                }            }        }        private void InitializePlugin(IEnvironment env, IVisualControlsPlug plug)        {            plug.Initialize(env);            visualPlugs.Add(plug);        }//重载操作符 public IVisualControlsPlug this[string pluginId]        {            get            {                foreach (IVisualControlsPlug plug in visualPlugs)                    if (plug.PluginId == pluginId)                        return plug;                return null;            }        }