Recursiveness in "catch enter key" example?

Josz

Hello comunity,
Im learnig C++ and Qt.
Could someboydy help me to understand a paar lines in the "catch enter key" example? https://wiki.qt.io/How_to_catch_enter_key

part of code contains the next:

bool keyEnterReceiver::eventFilter(QObject* obj, QEvent* event)
{
    if (event->type()==QEvent::KeyPress) {
        QKeyEvent* key = static_cast<QKeyEvent*>(event);
        if ( (key->key()==Qt::Key_Enter) || (key->key()==Qt::Key_Return) ) {
            //Enter or return was pressed
        } else {
            return QObject::eventFilter(obj, event);  //<- here is the question
        }
        return true;
    } else {
        return QObject::eventFilter(obj, event);  //<- and here X-D
    }
    return false;
}

I suppose that the call "return QObject::eventFilter(obj, event);" is recursiveness, when right... Why?, Which is the purpose of that and not return false?? Why is not an infinite loop?

thanks in advance.

kshegunov

@Josz said in Recursiveness in "catch enter key" example?:

I suppose that the call "return QObject::eventFilter(obj, event);" is recursiveness, when right... Why?

Nope. This is delegating the call to the parent's implementation[1]. It's done whenever you don't care about the event, so you allow the parent class to (maybe) process it.

[1] https://www.oreilly.com/library/view/c-cookbook/0596007612/ch08s16.html

Josz

@kshegunov Thank you very much

kshegunov

You're welcome!