Work around for signal and slot argument limitation - qt

Question

I want to make a PushButton when it is clicked, its text change into 'clicked'. I tried it by
connect(button1, SIGNAL(clicked()), this, SLOT(markClicked(button1)));
where this refer to the MainWindow and
void MainWindow::markClicked(QPushButton *button) { button->setText("Clicked"); }
It does not seem to work because I think SLOT cannot take more arguments than SIGNAL. If there any approach to work around this limitation?
Thanks.

Answer 1

Qt signals/slots mechanism can only transfer signal to slot function with similar parameters. As a workaround, you should use QSignalMapper:
QSignalMapper mapper;
...
connect(button1, SIGNAL(clicked()), &mapper, SLOT(map()));
mapper.setMapping(button1, button1); // not sure whether this is mandatory or not
...
connect(&mapper, SIGNAL(mapped(QWidget*)), this, SLOT(markClicked(QWidget*)));
and function markClicked is
void MainWindow::markClicked(QWidget *widget) {
QPushButton *button = qobject_cast<QPushButton*>(widget);
button->setText("Clicked");
}

Answer 2

The other way you could do this is to use a default value for the argument and then use the sender() method:
In MainWindow:
void markClicked(QPushButton *button = NULL);
then:
connect(button1, SIGNAL(clicked()), this, SLOT(markClicked()));
and:
void MainWindow::markClicked(QPushButton *button) {
if (button==NULL) { button = qobject_cast<QPushButton*>(sender()); }
button->setText("Clicked");
}