Connect a SIGNAL to a SIGNAL with more arguments

[leonardo M B]

I have a SIGNAL that takes data as arguments and I would Like to connect to another SIGNAL that receives the same data, but also takes a boolean argument. This boolean argument I want to be the state of a checkbox. My idea was something like this:

connect(_periodSelector, SIGNAL(newDateTimes(QDateTime, QDateTime)), this, SIGNAL(changeAbsolutePeriods(QDateTime,QDateTime, bool =_checkbox->isChecked)));

How Can I do This?

[Emre MUTLU]

connect(_periodSelector,&_periodSelectorClass::newDateTimes,[this](QDateTime dateTime){
emit this->changeAbsolutePeriods(dateTime,_checkbox->isChecked());
};

i'm not sure but maybe something like this will work

[J.Hilk]

@leonardo-M-B by using the "new" connect syntax and a lambda as forth argument

or by going the along way and creating a slot in your class wherein you emit the new signal with the additional parameter

[Emre MUTLU]

connect(_periodSelector,&_periodSelectorClass::newDateTimes,[this](QDateTime dateTime){
emit this->changeAbsolutePeriods(dateTime,_checkbox->isChecked());
};

i'm not sure but maybe something like this will work

[SimonSchroeder]

In order to avoid some weird crashes, you should use a context object in your connect statement:

connect(_periodSelector,&_periodSelectorClass::newDateTimes,this,[this](QDateTime dateTime){
emit this->changeAbsolutePeriods(dateTime,_checkbox->isChecked());
};

(notice the extra this as third argument)

Otherwise, if the object pointed to by this is destroyed, the connection will not disconnect automatically. Once the lambda is then executed it will have a dangling this pointer. With these kinds of lambdas (that just wrap another function call) it is usually quite easy to find the right context object.