XE8-indy10中关于TIdTCPClientCustom.Connect的源码和解读

TIdTCPClientCustom.Connect源码如下，中文注释是自己写的。

procedure TIdTCPClientCustom.Connect;begin  if Connected then begin    EIdAlreadyConnected.Toss(RSAlreadyConnected);//如果已经连接则抛出AlreadyConnected的异常  end;  if Host = '' then begin    EIdHostRequired.Toss('');//如果Host为空，则抛出EIdHostRequired的异常  end;  if Port = 0 then begin    EIdPortRequired.Toss('');//如果Host为空，则抛出EIdPortRequired的异常  end;  if IOHandler = nil then begin    IOHandler := MakeImplicitClientHandler;    IOHandler.OnStatus := OnStatus;//改变OnStatus的状态    ManagedIOHandler := True;  end;  try    // Bypass GetDestination    if FDestination <> '' then begin      IOHandler.Destination := FDestination;    end;{BGO: not any more, TIdTCPClientCustom has precedence now (for port protocols, and things like that)    // We retain the settings that are in here (filled in by the user)    // we only do this when the iohandler has no settings,    // because the iohandler has precedence    if (IOHandler.Port = 0) and (IOHandler.Host = '') then begin      IOHandler.Port := FPort;      IOHandler.Host := FHost;    end;}    IOHandler.Port := FPort; //BGO: just to make sure    IOHandler.Host := FHost;    IOHandler.ConnectTimeout := FConnectTimeout;    IOHandler.ReadTimeout := FReadTimeout;    if Socket <> nil then begin      Socket.BoundIP := FBoundIP;      Socket.BoundPort := FBoundPort;      Socket.BoundPortMin := FBoundPortMin;      Socket.BoundPortMax := FBoundPortMax;      Socket.IPVersion := FIPVersion;      Socket.ReuseSocket := FReuseSocket;      Socket.UseNagle := FUseNagle;      Socket.OnBeforeBind := FOnBeforeBind;      Socket.OnAfterBind := FOnAfterBind;      Socket.OnSocketAllocated := FOnSocketAllocated;    end;    IOHandler.Open;//打开IO    if IOHandler.Intercept <> nil then begin      IOHandler.Intercept.Connect(Self);    end;    DoStatus(hsConnected, [Host]);    DoOnConnected;//调用OnConnected函数  except//捕捉异常    if IOHandler <> nil then begin      IOHandler.Close;      if ManagedIOHandler then begin        IOHandler := nil; // RLebeau - SetIOHandler() will free the IOHandler      end;    end;    raise;  end;end;