class - TObjectList<> Get item error -

i'm trying create tobjectlist class in delphi xe8, errors when try value.

compiler error message: "[dcc32 error] : can't access private symbol {system.generics.collections}tlist.getitem"

here code:

unit unit2; interface uses   classes, system.sysutils, system.types, rest.types, system.json, data.bind.components,   system.regularexpressions, system.variants,   generics.collections;    type   ttruc = class   public     libelle : string;     constructor create(plibelle : string);   end;    tlistedetrucs = class(tobjectlist<ttruc>)   private     function getitem(index: integer): ttruc;     procedure setitem(index: integer; const value: ttruc);   public     function add(aobject: ttruc): integer;     procedure insert(index: integer; aobject: ttruc);     procedure delete(index: integer);     property items[index: integer]: ttruc read getitem write setitem; default;   end;  implementation  { ttruc }  constructor ttruc.create(plibelle: string); begin   libelle := plibelle; end;  { tlistedetrucs }  function tlistedetrucs.add(aobject: ttruc): integer; begin   result := inherited add(aobject); end;  procedure tlistedetrucs.insert(index: integer; aobject: ttruc); begin   inherited insert(index, aobject); end;  procedure tlistedetrucs.delete(index: integer); begin   inherited delete(index); end;  function tlistedetrucs.getitem(index: integer): ttruc; begin   result := inherited getitem(index); end;  procedure tlistedetrucs.setitem(index: integer; const value: ttruc); begin   inherited setitem(index, value); end; end. 

the testing code :

procedure tform1.button1click(sender: tobject); var   l : tlistedetrucs;   : integer;   obj : ttruc; begin   l := tlistedetrucs.create(true);   l.add(ttruc.create('one'));   l.add(ttruc.create('two'));   obj := ttruc.create('three');   l.add(obj);   := 0 l.count - 1   begin     showmessage(l[i].libelle);   end;   l.delete(0);   l.extract(obj);   l.free; end; 

how can make work ?

well, getitem, , indeed setitem private. code cannot see them. private members can seen in unit in declared. need use members @ least protected.

this compiles:

function tlistedetrucs.getitem(index: integer): ttruc; begin   result := inherited items[index]; end;  procedure tlistedetrucs.setitem(index: integer; const value: ttruc); begin   inherited items[index] := value; end; 

in case class little pointless because none of methods in class vary behaviour base class. peut-être real class more.