DeleteLater never deletes...

Dariusz

Hey

Loosing my marbles here... simple program:

#include "QWidget";

class A {
public:
    virtual ~A() {
        std::cout << "~A\n";
    }
};
class aX {
public:
    virtual ~aX() {
        std::cout << "~aX\n";
    }
};

class B : A {
public:
    virtual ~B() override {
        std::cout << "~B\n";
    }
};

class C : public QWidget, public B, public aX {
public:
    ~C() {
        B::~B();
        aX::~aX();
        std::cout << "~C\n";
    }
};

int main(int argc, char *argv[]) {
    qInstallMessageHandler(icDisplayDebugHandler);
    QApplication a(argc, argv);
    C *c = new C;
    c->deleteLater();
    QWidget w;
    w.show();
    return a.exec();

The C never gets deleted, what do I do to delete it ?!
I want to remove my subclassed widget from layout & delete it, but I just keep on hoging more and more memory :- (

TIA

SGaist

Hi,

What version of Qt ?
On what OS ?
How did you determine that it is not happening ?

Working fine on macOS, with Qt 5.13
I had to remove your custom message handling since you didn't provide it though.

Dariusz

@SGaist Yeah seems to work... Whhhh frustrating !

The message handling was skewing my test sigh.

Ok so my error must be else where... if I want to remove widget & delete it... do I do this ?

for (auto *widgetObj:mDisplayDataWidgetPtr) { // widgetObj = my base class that has a QWidget* as member.
    widgetObj->getWidgetPtr()->setParent(nullptr);
    mLay_content->removeWidget(widgetObj->getWidgetPtr());
    widgetObj->getWidgetPtr()->deleteLater();
    //delete widgetObj;
}
qDeleteAll(mDisplayDataWidgetPtr);
mDisplayDataWidgetPtr.clear();

Would this function call deleteLater properly on that widget I just removed and it would remove all widgets from its layout/child layouts?

I'm struggling to clean up my complex gui : -(

TIA

SGaist

Why isn't that member widget deletion handled by the destructor of the class you store in mDisplayDataWidgetPtr ?

If I may, the mDisplayDataWidgetPtr name doesn't look like a list/vector/whatever which your code suggests it is. It's pretty confusing when reading your code. You might want to change it for something meaningful, it will help a lot for long term maintenance.

Dariusz

@SGaist Yup I agree should have called it better...

QVector<dataWidget*> mDisplayDataWidgetPtr;
    class datWidget{
        QWidget *mWidget;
    public:
        datWidget();
        ~datWidget()
        QWidget*getWidgetPtr(){return mWidget;}
    }

The question I have is...
when I do:

widgetObj->getWidgetPtr()->setParent(nullptr);
    mLay_content->removeWidget(widgetObj->getWidgetPtr());
    widgetObj->getWidgetPtr()->deleteLater();

will that delete mWidget from the class above, making it a invalid pointer/which is fine as then I just do delete mDisplayDataWidgetPtr[x]; or better just do qDeleteAll(mDisplayDataWidgetPtr);

Or do I need to delete it manually in dataWidget class?

I'm getting random errors when I try to delete items manually... I think they get delete call before/after qt starts deleting them and I end up with crash...

TIA

Christian Ehrlicher

You should really read the chapter about the parent/child relationship here: https://doc.qt.io/qt-5/qobject.html#details

".... The parent takes ownership of the object; i.e., it will automatically delete its children in its destructor"

So if they are all children of your mWidget then they will get deleted when mWidget is destroyed.