Delphi memory leak with pointer to TStringList

Question

I have problems understanding pointer behavior. I have a very simple example:

type
  PSL = ^TStringList;
...
var
  myPSL : PSL;
...
procedure TForm1.FormCreate(Sender: TObject);
begin
  New(myPSL);
  myPSL^ := TStringList.Create;
  myPSL^.Add('String 1');
  myPSL^.Add('String 2');
  myPSL^.Add('String 3');
end;
...
procedure TForm1.FormDestroy(Sender: TObject);
begin
  Dispose(myPSL);
end;

With this code I get a memory leak report

29 - 36 bytes: UnicodeString x 3
37 - 44 bytes: Unknown x 1
85 - 92 bytes: TStringList x 1

Now if i call

myPSL^.Free;

before deleting the pointer, then nothing is reported.

I do not understand why this is happening. I know that calling New () allocates enough memory (depending on the type of pointer), and calling Dispose () takes care to free the same memory, then why do I need a Free pointer, as if it were a "real" object?

Thank!

Answer 1

. . :

var
  myPSL : TStringList;
...
procedure TForm1.FormCreate(Sender: TObject);
begin
  myPSL := TStringList.Create;
  myPSL.Add('String 1');
  myPSL.Add('String 2');
  myPSL.Add('String 3');
end;
...
procedure TForm1.FormDestroy(Sender: TObject);
begin
  myPSL.Free;
end;

:

New(myPSL) Dispose(myPSL) / sizeof(TStringList) , / TStringList . myPSL := TStringList.Create myPSL.Free.

Answer 2

TStringList, TStringList . , myPSL :

var
   myPSL : TStringList;
...
procedure TForm1.FormCreate(Sender: TObject);
begin
  myPSL := TStringList.Create;
  myPSL.Add('String 1');
  myPSL.Add('String 2');
  myPSL.Add('String 3');
end;
...
procedure TForm1.FormDestroy(Sender: TObject);
begin
  myPSL.Free;
end;

- , , Free, myPSL:

myPSL^.Free;
dispose(myPSL);