QVariant with QString / who free's its data?

[elias.bachaalany]

Hello,

Suppose I have the following:

QAction *a = ....

a->setData(QString("Hello world"))
QObject::connect(a, ....)

Later in my slot:

QAction *a = QObject::sender();

QString s = a->data()->toString()

This works fine. But I wonder who takes care of disposing the associated action data (in this case the QString)

[Lykurg]

Qt uses implicit sharing in some classes. So it does for QString:

Foo::Foo()
{
  QAction *a = QAction(this);
  a->setData(QString("Hello world"));
}
 
Foo::~Foo()
{
  // a gets destroyed and so also the string since a takes care of that. (And it the reference count is equal 0.
}
 
Foo::mySlot()
{
  QString s = a->data()->toString(); // s is not a real copy (as long as you don't change it
} // s gets deleted (or the reference count gets decreased.

Foo::Foo()
{
  QAction *a = QAction(this);
  a->setData(QString("Hello world"));
}

Foo::~Foo()
{
  // a gets destroyed and so also the string since a takes care of that. (And it the reference count is equal 0.
}

Foo::mySlot()
{
  QString s = a->data()->toString(); // s is not a real copy (as long as you don't change it
} // s gets deleted (or the reference count gets decreased.

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