interface

uses
  Classes;

type
  TInputMethode = procedure(AValue: string) of object;

  TInputThread = class(TThread)
  private
    FDaten : string;
    FOnInput: TInputMethode;
  protected
    procedure DoOnInput;
    procedure Execute; override;
  public
    constructor create; virtual;
    property OnInput: TInputMethode read FOnInput write FOnInput;
  end;

  TInput = class(TPersistent)
  private
    FDaten : string;
    FInpThread : TInputThread;
  protected
    procedure DoInput(AValue: string);
  public
    constructor Create;
    destructor Destroy; override;
  published
  end;

implementation

{ TInputThread }

procedure TInputThread.DoOnInput;
begin
  if Assigned(FOnInput) then
    FOnInput(FDaten);
end;

procedure TInputThread.execute;
begin
// while not Terminated do;
  FDaten := 'test';
  Synchronize(DoOnInput);
end;

constructor TInputThread.create;
begin
  inherited create(true); // CreateSuspended = true
  // problematisch da TInput eine Zeiger auf den Thread besitzt
  // freeOnTerminate := true;
  freeOnTerminate := False;
end;

{ TInput }

constructor TInput.Create;
begin
  inherited;
  FInpThread := TInputThread.Create;
  FInpThread.OnInput := DoInput;
  FInpThread.Resume;
end;

destructor TInput.Destroy;
begin
  FInpThread.Free;
  inherited;
end;

procedure TInput.DoInput(AValue: string);
begin
  FDaten := AValue;
  {...}
end;