cleanup handler on application close

[err23]

hi, i have a small application which builds up a connection to a digital camera. To take a photo you have to set up "releaseMode". After the desired camera operations you have to part this releaseMode to finish clean. Otherwise you couldn't enter the releaseMode again.

so i need to do some cleanup operations. How to realize this? I thought about handling the QCoreApplication::aboutToQuit() signal, but it doesn't work yet.

Here my little test application

the receiver-class

class Nonce : public QObject
{
	Q_OBJECT
 
public:
	Nonce();
	~Nonce();
 
public slots:
	void quitter();
 
};

class Nonce : public QObject
{
	Q_OBJECT

public:
	Nonce();
	~Nonce();

public slots:
	void quitter();

};

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quitter method

void Nonce::quitter()
{
	std::cout << " aboutToQuit emitted "<< std::endl << std::flush;
}

void Nonce::quitter()
{
	std::cout << " aboutToQuit emitted "<< std::endl << std::flush;
}

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and a small main()

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
	Nonce foo; 
 
	QObject::connect(&a, SIGNAL(aboutToQuit()),
					 &foo, SLOT(quitter()));
 
	return a.exec();
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

	Nonce foo; 

	QObject::connect(&a, SIGNAL(aboutToQuit()),
					 &foo, SLOT(quitter()));

	return a.exec();
}

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so.. when i "kill" the programm anyway the quitter method should be started, there i want leave the releaseMode.

any Ideas where are my faults? (yeah, I am quite new to Qt)

[jacek]

when i "kill" the programm anyway the quitter method should be started

When you kill your application, it is terminated immediately.

[ball]

Jacek, actually how to properly end a QCoreApplication to trigger aboutToQuit() signal, without pressing the 'X' button in right-top corner, or type Ctrl+C in keyboard? Both of these 2 actions will still KILL the QCoreApplication immediately.

When you kill your application, it is terminated immediately.

[jacek]

Jacek, actually how to properly end a QCoreApplication to trigger aboutToQuit() signal, without pressing the 'X' button in right-top corner, or type Ctrl+C in keyboard? Both of these 2 actions will still KILL the QCoreApplication immediately.

There are many ways. If it has a some form of CLI, then you have to implement proper command or if it works more like a daemon, you can use some IPC mechanism (like signals).

AFAIR Ctrl+C should send SIGINT and that 'X' button -- SIGTERM, so you can use your own handler that will send a custom event to your application object to make it invoke quit(). Of course this means that your console application must be event-driven.