QList of object

  • Hi,

    I'm developping a Qt application that use the GPIO of my pcDuino (GPIO are just seen as files).
    I use buttons with leds that must switch on when the button is pressed.

    It's working fine, and I want now to make my application more generic and parametrable.
    So, I'm using QSettings to allow the changing some parameters dynamically. What I want to do is choose wich gpio port matches wich buttons and leds in my settings file.
    So, to create dynamically my objects I use a QList I append for all new parameters I'm reading from my file.
    Then, I make a connection to switch on/off my led, regarding the state of the button.

    My problem is that with the parametrable version, using QList, my program never runs into my connect function.
    While my non-parametrable version was perfectly working.

    Here is my code :
    @ settings.beginGroup("LedButton");
    QStringList gpioGroupList = settings.childGroups();
    int nbGPIO = gpioGroupList.count();
    QList<LedButton *> gpioButtonLedList;
    for (int i=0; i<nbGPIO;i++)
    qWarning() << "gpio n°" << i << gpioGroupList[i] << "=" << settings.value(gpioGroupList[i]+"/button").toInt() << "/" << settings.value(gpioGroupList[i]+"/led").toInt();
    GeneralPurposeIO gpioButton(settings.value(gpioGroupList[i]+"/button").toInt());
    qWarning() << "button"<< i <<"not opened";

        GeneralPurposeIO gpioLed(settings.value(gpioGroupList[i]+"/led").toInt());
        if (!gpioLed.open(GeneralPurposeIO::Mode::Output))
            qWarning() << "led"<< i <<"not opened";
        LedButton *ledButton = new LedButton(&gpioLed, &gpioButton, qApp);
    for(int i=0; i<gpioButtonLedList.count();i++)
        QObject::connect(gpioButtonLedList[i], &LedButton::toggled, [](bool checked)
            qWarning() << "checked" << checked;


    And here is my non-parametrable version that works :

    @ GeneralPurposeIO buttonIO(0);
    qWarning() << "gpio0 not opened";
    return -1;

    GeneralPurposeIO ledIO(8);
    if (!ledIO.open(GeneralPurposeIO::Mode::Output))
        qWarning() << "gpio8 not opened";
        return -1;
    LedButton button08( &ledIO, &buttonIO);
    QObject::connect(&button08, &LedButton::toggled, [](bool checked)
        qWarning() << "button08 :" << checked;

    Does anybody sees a mistake in the first code ?


  • Moderators

    LedButton *ledButton = new LedButton(&gpioLed, &gpioButton, qApp);

    gpioLed and gpioButton are created on the stack inside the for loop. That means those objects are destroyed when they go out of scope (when loop cycle ends).

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