why is the sender's type of the destroyed() signal QPushButtonPrivate?

[iwatsu]

I have a delegate class that inherits from QStyledItemDelegate. In SlotDestroyed(): why is sender() of the type QPushButtonPrivate and not QPushButton?

QWidget *Delegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option,	const QModelIndex &index) const
{
  QPushButton *btn = new QPushButton(parent);
  btn->setText("test");
 
  connect(btn, SIGNAL(destroyed(QObject*)), this, SLOT(SlotDestroyed(QObject*)));
  return btn;
}
 
 
void Delegate::SlotDestroyed(QObject* editor)
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender()); // why null?
	QObject *s = sender();
	btn = reinterpret_cast<QPushButton*>(sender());
}

QWidget *Delegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option,	const QModelIndex &index) const
{
  QPushButton *btn = new QPushButton(parent);
  btn->setText("test");

  connect(btn, SIGNAL(destroyed(QObject*)), this, SLOT(SlotDestroyed(QObject*)));
  return btn;
}


void Delegate::SlotDestroyed(QObject* editor)
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender()); // why null?
	QObject *s = sender();
	btn = reinterpret_cast<QPushButton*>(sender());
}

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[DanH]

Probably because QPushButton is implemented in two parts, with an outer "public" class and an inner "private" one. Lots of Qt classes have this two-part implementation, for "security" reasons, to make it easier for object data to be shared, and to make object assignment simpler and lighter-weight.

However, the behavior you've discovered is probably technically a bug.

[ChrisW67]

Out of interest, how are you going to use a pointer to an object that is advertising its imminent demise?

[iwatsu]

To release some resources (which I'm doing in the destructor now). I was just wondering if that's a bug or if there is a reason for that behavior.