Class helpers inheritance

ClassHelpers.pas

program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type
  TThirdPartyHelper = class helper for TObject
  public
    procedure SayHello; // virtual;
  end;

  TMyHelper = class helper (TThirdPartyHelper) for TObject
  public
    procedure SayHello; // override;
    procedure SayHi;
  end;

{ TThirdPartyHelper }

procedure TThirdPartyHelper.SayHello;
begin
  Writeln('Hello, world!');
end;

{ TMyHelper }

procedure TMyHelper.SayHello;
begin
  inherited SayHello; // does work if you dont specify method name explicitly
  Writeln('My hello!');
end;

procedure TMyHelper.SayHi;
begin
  Writeln('Hi all!');
end;

var
  X: TObject;

begin
  X := TObject.Create;
  try
    X.SayHello;
    X.SayHi;
  finally
    FreeAndNil(X);
  end;
  Readln;
end.

Outputs:
Hello, world!
My hello!
Hi all!