Simple way to have radio buttons call same function with different parameter?

kitfox

I'm creating a set of QRadioButton where each button is triggering essentially the same action but with a different value. For example:

      QRadioButton* bn1 = new QRadioButton("1");
      connect(bn1, &QRadioButton::clicked, this, &MyClass::setStation1);
      
      QRadioButton* bn2 = new QRadioButton("2");
      connect(bn2, &QRadioButton::clicked, this, &MyClass::setStation2);
            
      QRadioButton* bn2 = new QRadioButton("3");
      connect(bn3, &QRadioButton::clicked, this, &MyClass::setStation3);

It would be convenient to replace each of the setStation*() slot methods with a single method setStation(int station) and just pass the index of the station. Is there a way to do this?

JonB

@kitfox
One way is to use a lambda to pass a parameter, like

QRadioButton* bn1 = new QRadioButton("1");
connect(bn1, &QRadioButton::clicked, this, [=] () { this->setStation(1); } );

QRadioButton* bn2 = new QRadioButton("2");
connect(bn2, &QRadioButton::clicked, this, [=] () { this->setStation(2); } );

This example could also be done with QSignalMapper Class, but lambdas are more usual now.

SGaist

Hi,

You could use lambdas for that.

JonB

@kitfox
One way is to use a lambda to pass a parameter, like

QRadioButton* bn1 = new QRadioButton("1");
connect(bn1, &QRadioButton::clicked, this, [=] () { this->setStation(1); } );

QRadioButton* bn2 = new QRadioButton("2");
connect(bn2, &QRadioButton::clicked, this, [=] () { this->setStation(2); } );

This example could also be done with QSignalMapper Class, but lambdas are more usual now.

Bonnie

There is also another old-fashioned way : getting data from the sender.

void MyClass::setStation() {
    if(QRadioButton *button = qobject_cast<QRadioButton*>(sender())) {
       QString text = button->text();
        if(text == "1") {
        } else if(text == "2") {
        }
    }
}

But lambdas are way more flexible.

JonB

@Bonnie
There is, but IIRC (I think I read it somewhere) sender() == nullptr if slot called via lambda?