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View Full Version : Run Time error: Object::connect: No such slot dlgTextScroller::pbPreview_clicked(app)



ashukla
8th October 2007, 15:54
Dear ................!

I have a need of QApplication app(int argc,char **argv) variable (which is declared in main.cpp) in pbPreview_clicked() slot.
/*In dlgtextscroller.h I have defined the slot as follows*/
private slots:
virtual void pbPreview_clicked(QApplication *app);


/*In dlgTextScroller constructor I connected the pbPreview clicked( ) push button signal to dlgTextscroller pbPreview_clicked(app) as follows*/

dlgTextScroller::dlgTextScroller( QApplication *app, QWidget* parent)
: QDialog(parent)
{
setupUi(this);
connect( pbPreview, SIGNAL( clicked() ), this, SLOT( pbPreview_clicked(app) ));
}

void dlgTextScroller::pbPreview_clicked(QApplication *app)
{
...
...
...
}

It doesn't give any comile time error but when I ran, it gives the following error and show the dialog.........

Object::connect: No such slot dlgTextScroller::pbPreview_clicked(app)
Object::connect: (sender name: 'pbPreview')
Object::connect: (receiver name: 'dlgTextScroller')

Thanks in advance........!

jpn
8th October 2007, 15:59
The QApplication object is accessible through the QCoreApplication::instance() function which return a pointer equivalent to the global qApp (http://doc.trolltech.com/latest/qapplication.html#qApp) pointer

jacek
8th October 2007, 16:02
connect( pbPreview, SIGNAL( clicked() ), this, SLOT( pbPreview_clicked(app) ));
You can't put values, variables and parameter names inside SLOT and SIGNAL macros.

You can store that pointer in a member variable -- there's no point in passing it as a parameter to a method of the same class. Another solution is to use QCoreApplication::instance().