source: branches/simple/Pin.pas

unit Pin;

interface

uses
  Classes, SysUtils;

type
  TWriteEvent = procedure (Data: Byte) of object;
  TReadEvent = function: Byte of object;

  { TPin }

  TPin = class
  private
    FOnRead: TReadEvent;
    FOnWrite: TWriteEvent;
    FAnother: TPin;
  public
    procedure Write(Data: Byte);
    function Read: Byte;
    procedure Disconnect;
    procedure Connect(Pin: TPin);
    property OnWrite: TWriteEvent read FOnWrite write FOnWrite;
    property OnRead: TReadEvent read FOnRead write FOnRead;
  end;

  TPin8 = class(TPin)
  end;


implementation

{ TPin }

procedure TPin.Write(Data: Byte);
begin
  if Assigned(FAnother) then FAnother.Write(Data);
end;

function TPin.Read: Byte;
begin
  if Assigned(FAnother) then Result := FAnother.Read
    else Result := 0;
end;

procedure TPin.Disconnect;
begin
  if Assigned(FAnother) then begin
    FAnother.FAnother := nil;
    FAnother := nil;
  end;
end;

procedure TPin.Connect(Pin: TPin);
begin
  if Assigned(FAnother) then Disconnect;
  FAnother := Pin;
  Pin.FAnother := Self;
end;

end.