anchor.diff:  
   function TmVirtualFieldDefs.FindByName(const aName: string): TmVirtualFieldDef;
   var
  -  tmp : pointer;
     i : integer;
   begin
     if FIndex.Count = 0 then
  
positive.code: 
  uses
    Classes, DB,
    StrHashMap;
  
  type
  
  
negative.code: constructor TmVirtualFieldDefs.Create;
  begin
    inherited Create(TmVirtualFieldDef);
    FIndex := TmStringDictionary.Create(false);
  end;
  
  destructor TmVirtualFieldDefs.Destroy;
  