[0nni]

Код:

unit Unit1;

interface

type
  //базоый объект
  TMyCustomObject = class
    constructor Create;
    destructor Destroy; override;
  end;

procedure Clear;
function IsValidObject(Obj : TObject) : Boolean;

implementation

Uses
  Classes;

var
  Objects : TList;

procedure Clear;
var
  i : Integer;
begin
  for I := 0 to Objects.Count - 1 do TObject(Objects[0]).free;
end;

//функция проверки
function IsValidObject(Obj : TObject) : Boolean;
begin
  Result := Objects.IndexOf(Obj) <> -1;
end;

{ TMyCustomObject }

constructor TMyCustomObject.Create;
begin
  Objects.Add(self);
end;

destructor TMyCustomObject.Destroy;
var
  index : Integer;
begin
  index := Objects.IndexOf(self);
  if index <> -1 then Objects.Delete(index);
  inherited;
end;

initialization

  Objects := TList.Create;

finalization
  Clear;
  Objects.Free;
end.