No such Slot/Signals (Qt)

Question

Object::connect: No such signal RollsRoyceTab::signal_aValueChange(int aValue) ??????

I have

class RollsRoyceTab : public QWidget
 {
     Q_OBJECT
 p         


        

Answer 1

First: signals and slots in QObject::connect() should be without variables names.

Second: You can't connect signal with one argument with SLOT with three arguments. SIGNAL must not have fewer arguments than the SLOT.

It should be for e.g.:

connect(this,SIGNAL(signal_aValueChange(int)),this,SLOT(rrValuesHolder(int)));

And it's simply explanation for that. If you emit signal with one argument (for e.g. QString) how would slot know what are others two arguments? For me it's logical.

Answer 2

"SIGNAL() macro must NOT have fewer arguments than the signature passed to the SLOT() macro.

All of these would work:

connect(sender, SIGNAL(destroyed(QObject*)), this, SLOT(objectDestroyed(Qbject*)));
connect(sender, SIGNAL(destroyed(QObject*)), this, SLOT(objectDestroyed()));
connect(sender, SIGNAL(destroyed()), this, SLOT(objectDestroyed()));

This does not work:

connect(sender, SIGNAL(destroyed()), this, SLOT(objectDestroyed(QObject*)));

I believe you should call as value SLOT(rrValuesHolder(int))

Reference: http://qt-project.org/doc/qt-4.8/signalsandslots.html

EDIT: Blood included one additional piece of information that I neglected, Signals and Slots should be connected without variable names!