TSAttribute = class(TCustomAttribute)
     private
          FName: string;
     public
          constructor Create(const Name : string);
          property Name : string read FName write FName;
     end;

TSomething = class
end;

[TS('Dog')]
TDog = class(TSomething)
end;

[TS('Cat')]
TCat = class(TSomething)
end;

...
var DogID, CatID:integer;
implementation
uses DogUnit,CatUnit;

constructor TMain.Create();
     begin
          inherited;
          objectTypes := TTypesList.Create ;//TTypesList это TList
          objectTypes.Add(TDog); DogID:=objectTypes.Count-1; {0}
          objectTypes.Add(TCat);  CatID :=objectTypes.Count-1; {1}
     end;