program Project13;

{$APPTYPE CONSOLE}

uses
  System.Classes
, System.SysUtils
, Windows
;

Type
  INotify = Interface
    ['{27E27AAC-63A6-4289-8B58-BCD4039AAE6C}']
    Procedure Ready(Value : Integer);
  End;

  TNotify = Class(TInterfacedObject,INotify)
    strict private
      Procedure Ready(aValue : Integer);
    private
      fValue : Integer;
      fOnReady : TProc<Integer>;
    public
      Constructor Create(aProc : TProc<Integer>);
      Destructor Destroy;override;
  end;

  TWorker = Class(TThread)
    Protected
      Procedure Execute;override;
    private
      fNotify : INotify;
    public
      Constructor Create(aNotify : INotify);
  End;


{ TNotify }

constructor TNotify.Create(aProc: TProc<Integer>);
begin
  Inherited Create;

  fOnReady := aProc;
end;

destructor TNotify.Destroy;
begin
  fOnReady(fValue);

  inherited;
end;

procedure TNotify.Ready(aValue: Integer);
begin
  fValue := aValue;
end;

{ TWorker }

constructor TWorker.Create(aNotify: INotify);
begin
  fNotify := aNotify;

  FreeOnTerminate := true;

  inherited Create(false);
end;

procedure TWorker.Execute;
begin
  Sleep(5000);
  fNotify.Ready(42);
end;

var
  Worker : TWorker;
begin
  try
    Worker := TWorker.Create(TNotify.Create(Procedure (aValue : Integer)
      begin // Still Thread Context
       Writeln(aValue,' MainThread:',Windows.GetCurrentThreadId() = System.MainThreadID);
      end));
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
  Readln;
end.