Why can a QObject not be set as parent of a QWidget?

Asked Jul 08 '16 at 12:17

Active Jul 08 '16 at 12:17

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Is it possible to set a QObject as parent of a QWidget, so the QWidget is deleted when the QObject is deleted?

The following code doesn't compile:

QObject a;
QObject b;
QWidget c;

b.setParent(&a); // This works
c.setParent(&a); // This fails: error C2664: 'void QWidget::setParent(QWidget *,Qt::WindowFlags)': cannot convert argument 1 from 'QObject *' to 'QWidget *'

Even though QWidget inherits from QObject! So why is the setParent(QObject*) function not available in QWidget anymore?

asked Jul 08 '16 at 12:17

Jan Rüegg

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There's no need to do that. Add the widget as a by-value member in the parent object, or use a by-value late initialization trick. – Kuba hasn't forgotten Monica Jul 08 '16 at 12:46
Great idea, thanks! – Jan Rüegg Jul 08 '16 at 12:52
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Another way, if you must create widgets with `new` for some reason, is to connect "parent" QObject's `destroyed` signal to widget's `deleteLater` slot. – hyde Jul 14 '16 at 14:03
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Cool idea, thanks. I ended up using the "Qt::WA_DeleteOnClose" in the end, though... – Jan Rüegg Jul 14 '16 at 14:07

Why can a QObject not be set as parent of a QWidget?

0 Answers0