aboutToQuit() signal from QCoreApplication

[googie]

Is there any possibility if slot connected to aboutToQuit() signal is really called? The cout doesn't work (which is also described in docs). Is there anything I can do to make sure?

[wysota]

Is there any possibility if slot connected to aboutToQuit() signal is really called?

Why not?

#include <QApplication>
#include <QPushButton>
#include <QtDebug>
 
class Button : public QPushButton {
  Q_OBJECT
public slots:
  void doSomething() { qDebug() << "About to quit!"; }
};
 
#include "main.moc"
 
int main(int argc, char **argv){
  QApplication app(argc, argv);
  Button button;
  button.setText("Click me");
  QObject::connect(&app, SIGNAL(aboutToQuit()), &button, SLOT(doSomething()));
  QObject::connect(&button, SIGNAL(clicked()), &app, SLOT(quit()));
  button.show();
  return app.exec();
}

#include <QApplication>
#include <QPushButton>
#include <QtDebug>

class Button : public QPushButton {
  Q_OBJECT
public slots:
  void doSomething() { qDebug() << "About to quit!"; }
};

#include "main.moc"

int main(int argc, char **argv){
  QApplication app(argc, argv);
  Button button;
  button.setText("Click me");
  QObject::connect(&app, SIGNAL(aboutToQuit()), &button, SLOT(doSomething()));
  QObject::connect(&button, SIGNAL(clicked()), &app, SLOT(quit()));
  button.show();
  return app.exec();
}

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[googie]

Does it work for you when you close application from command line by pressing Ctrl+c ?

[wysota]

It will work if you install an appropriate signal handler. Otherwise the application is instantly terminated by the operating system and doesn't have a chance to do anything.

#include <QApplication>                                                                                               
#include <QPushButton>                                                                                                
#include <QtDebug>                                                                                                    
#include <signal.h>                                                                                                   
 
 
class Button : public QPushButton {
  Q_OBJECT
public slots:
  void doSomething() { qDebug() << "About to quit!"; }
};
 
#include "main.moc"
 
void signalhandler(int sig){
  if(sig==SIGINT){
    qApp->quit();
  }
}
 
int main(int argc, char **argv){
  QApplication app(argc, argv);
  Button button;
  button.setText("Click me");
  QObject::connect(&app, SIGNAL(aboutToQuit()), &button, SLOT(doSomething()));
  QObject::connect(&button, SIGNAL(clicked()), &app, SLOT(quit()));
  button.show();
  signal(SIGINT, signalhandler);
  return app.exec();
}

#include <QApplication>                                                                                               
#include <QPushButton>                                                                                                
#include <QtDebug>                                                                                                    
#include <signal.h>                                                                                                   


class Button : public QPushButton {
  Q_OBJECT
public slots:
  void doSomething() { qDebug() << "About to quit!"; }
};

#include "main.moc"

void signalhandler(int sig){
  if(sig==SIGINT){
    qApp->quit();
  }
}

int main(int argc, char **argv){
  QApplication app(argc, argv);
  Button button;
  button.setText("Click me");
  QObject::connect(&app, SIGNAL(aboutToQuit()), &button, SLOT(doSomething()));
  QObject::connect(&button, SIGNAL(clicked()), &app, SLOT(quit()));
  button.show();
  signal(SIGINT, signalhandler);
  return app.exec();
}

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