public override void Assign(RepositoryItem item)
 {
     BeginUpdate();
     try
     {
         base.Assign(item);
         RepositoryItemMyLookUpEdit source = item as RepositoryItemMyLookUpEdit;
         if (source == null)
         {
             return;
         }
         //
     }
     finally
     {
         EndUpdate();
     }
 }
 static MyLookUpEdit()
 {
     RepositoryItemMyLookUpEdit.RegisterMyLookUpEdit();
 }