QCoreApplication::arguments() remove `-style` arguments passed to the app

Mesrine

Hello everyone,
I am trying to restart a GUI app with the same style set by the command line.
To start the app from the command line i do

./nftminter  --style Esterv.Controls.Flat

To restart the app with the same style I use QCoreApplication::arguments() to do

QProcess::startDetached(QCoreApplication::applicationFilePath(), QCoreApplication::arguments(),QString(),&pid);

But it seems that the style is not present in the QCoreApplication::arguments() result.

You can test that the style is not present on the output of QCoreApplication::arguments() with this simple example.


#include <QGuiApplication>
#include <QQmlApplicationEngine>
    int main(int argc, char *argv[])
{

    qDebug()<<"argc:"<<argc;
    for(int i=0;i<argc;i++)
    {
        qDebug()<<argv[i];
    }
    QGuiApplication app(argc, argv);


    auto args=QCoreApplication::arguments();
    qDebug()<<"argsc:"<<args.size();
    qDebug()<<"args:"<<args;

    return app.exec();
}

by executing `./nftminter  --style Esterv.Controls.Flat -hello`

give the output

argc: 4
./nftminter
--style
Esterv.Controls.Flat
-hello
argsc: 2
args: QList("./nftminter", "-hello")

It makes sense that the style is only stored on the QGuiapplication class and not in QCoreApplication. But then how can i restart the app with the same style?

JonB

@Mesrine
I cannot find the exact doc spot[*], but Qt programs recognise a certain number of command line options as "internal" to it. See https://doc.qt.io/qt-6/qcommandlineparser.html#details

Known limitation: the parsing of Qt options inside QCoreApplication and subclasses happens before QCommandLineParser exists, so it can't take it into account. This means any option value that looks like a builtin Qt option will be treated by QCoreApplication as a builtin Qt option. Example: --profile -reverse will lead to QGuiApplication seeing the -reverse option set, and removing it from QCoreApplication::arguments() before QCommandLineParser defines the profile option and parses the command line.

--style is doubtless one of these.

You probably need to revert to what arrived in argv[] if you want to replicate the exact command-line options passed to a Qt program.

[*]
Found them for QGuiApplication::QGuiApplication(int &argc, char **argv).
I don't see --style listed there. I don't know how it behaves for QCoreApplication. But --style seems like a reasonable additional one to specify style.
Hmm, see QApplication::QApplication(int &argc, char **argv) lists --style as applying to QApplication.