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[Solved] QStringList getting qApp->arguments() issues

  • Hello there !

    I'm on a new project since few days and while rewriting the main() body, I have a really strange issue concerning QStringList and qApp->arguments. Actually, I have an "AppController" (It's not MVC, don't care about *Controller please ;) ) in the main which receives qApp->arguments() (if none given to the constructor) which then copy it to an internal QStringList. In the constructor, every QDebug work fine, in the method called next (::run2()) my internal QStringList seems to be empty... And sometimes cause EXC_BAD_ACCESS.

    @#include <QApplication>
    #include <QDebug>
    #include <QIcon>

    #include "AgentController/AgentController.hpp" // Contains only declarations
    #include "AppController/AppController.hpp"

    int main(int argc, char *argv[])
    QApplication a(argc, argv);
    AppController *appController;

    a.setQuitOnLastWindowClosed(true); // Agent disabled for now
    appController = new AppController;
    return a.exec&#40;&#41;;




    include <QCoreApplication> // MAYBE... That could be the problem

    include <QObject>

    include <QSettings>

    include <QStringList>

    class AppController : public QObject

        QSettings           m_settings;
        QStringList const&  m_argv;
        QStringList         m_filesToBackup;
        AppController(QStringList const& argv = qApp->arguments(&#41;,
                      QObject *parent = 0);
    public slots:
        void        run2(void);
        void        quitting(void);


    #endif // APPCONTROLLER_HPP@

    @#include <QDebug>
    #include <QString>
    #include <QUuid>

    #include <signal.h>

    #include "AppController.hpp"
    #include "../InitWidget/InitWidget.hpp" // Contains only declarations
    #include "../AgentController/AgentController.hpp" // Contains only declarations

    AppController::AppController(QStringList const& argv, QObject *parent)
    : QObject(parent), m_argv(argv)
    qDebug() << "Args:" << qApp->arguments();
    qDebug() << "Args:" << argv;
    qDebug() << "Args:" << this->m_argv;
    if (signal(SIGUSR1, AgentController::signal_received) == SIG_ERR) {
    qDebug() << "Cannot attach signal handler";

    connect(qApp, SIGNAL(aboutToQuit()), SLOT(quitting()));


    // Signals / Slots
    void AppController::run2(void)
    // First start: Generate UUID
    if (this->m_settings.value("general/uuid").toUuid().isNull()) {
    this->m_settings.setValue("general/uuid", QUuid::createUuid());
    // ---

    // Parameters checking
    //  Help - Console
    qDebug() << "Internal argv ("+QString::number(this->m_argv.count())+"):"; // Raises EXC_BAD_ACCESS
    qDebug() << this->m_argv;
    if (this->m_argv.count() > 1 && this->m_argv.contains("--help")) {
        qDebug() << "Usage:";
        qDebug() << this->m_argv.at(0) << "[options] [file1 ...]\n";
        qDebug() << "Options:";
        qDebug() << "--help     This message";
        qDebug() << "--agent    Start in agent (background daemon) mode";
        qDebug() << "--backup   Start a backup process";
        qDebug() << "";
    //  ---
    // [...]


    void AppController::quitting(void)
    qDebug() << "Quitting.";
    // ---

    qDebug() log:
    @Args: ("XXX_PATH", "--backup", "/Users/Max13/Desktop/favicon.ico") // AppController.cpp:14 (Constructor)
    Args: ("XXX_PATH", "--backup", "/Users/Max13/Desktop/favicon.ico") // AppController.cpp:15 (Constructor)
    Args: ("XXX"_PATH, "--backup", "/Users/Max13/Desktop/favicon.ico") // AppController.cpp:16 (Constructor)
    "Internal argv (3):" // AppController.cpp:35 (run2())
    End of debug.@

    Can anyone tell me if I messed something up, or anything? Strangely, it raises EXC_BAD_ACCESS sometimes not everytime I start the app, debug mode or debugging mode. Now I'm writing, MAYBE it's because I'm including <QCoreApplication> instead of <QApplication> sometimes so MAYBE <QApplication> reimplements arguments() so calling it from qApp in a place or another won't give me the good behaviour.

    Anyway, it's doesn't seem to the THE problem for me because I'm calling qApp->arguments() in my contructor and it works. I'm checking in case of.

    Thank you for your help.

  • Moderators

    This does not really seem wrong in any way, apart from twisted argv declaration. Change it to the following:
    const QStringList &argv
    // instead of
    QStringList const& argv

  • @
    AppController(QStringList const& argv = qApp->arguments(),
    QObject *parent = 0);

    try to change to:

    AppController(const QStringList &a = QStringList(), ...)
    if (a.isEmpty())
    a = qApp()->arguments();


  • @sierdzio: I thought it was equivalent ^^'

    @Peppy: Removed the const in my class variable, did what you've suggested and of course after 5 launches, no bad access.

    Thank you to both of you, but can you explain me what could be the reason of this fail please ?

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