Qt 5.2 and QWeakPointer error: no match for 'operator='

[jiveaxe]

Hi,
I'm porting my qt4 application to qt5. While it compiled successfully in qt 5.1 (if I'm not wrong), with version 5.2 I got the following compile error:

no match for ‘operator=’ (operand types are ‘QWeakPointer<MainWindow>’ and ‘MainWindow*’)

The error is triggered at this line:

m_mainWindow = new MainWindow();

m_mainWindow = new MainWindow();

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where m_mainWindow is:

QWeakPointer<MainWindow> m_mainWindow;

QWeakPointer<MainWindow> m_mainWindow;

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and this is MainWindow:

mainwindow.h

//...
namespace Ui {
class MainWindow;
}
 
class MainWindow;
 
namespace The {
    MainWindow* mainWindow();
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
    friend MainWindow* The::mainWindow();
 
public:
    explicit MainWindow(QWidget *parent = 0);
    virtual ~MainWindow();
//...
};

//...
namespace Ui {
class MainWindow;
}

class MainWindow;

namespace The {
    MainWindow* mainWindow();
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
    friend MainWindow* The::mainWindow();

public:
    explicit MainWindow(QWidget *parent = 0);
    virtual ~MainWindow();
//...
};

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mainwindow.cpp

QWeakPointer<MainWindow> MainWindow::s_instance;
 
namespace The {
    MainWindow* mainWindow() { return MainWindow::s_instance.data(); }
}
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui_(new Ui::MainWindow)
{
//...
}

QWeakPointer<MainWindow> MainWindow::s_instance;

namespace The {
    MainWindow* mainWindow() { return MainWindow::s_instance.data(); }
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui_(new Ui::MainWindow)
{
//...
}

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Anything changed in Qt 5.2 regarding QWeakPointer?

Regards

[anda_skoa]

If you are using QWeakPointer to track the window's life time, i.e. get the pointer reset to 0 when the window is deleted, then use QPointer instead.

Cheers,
_

[ChrisW67]

QWeakPointer taking a QObject* was marked deprecated in Qt 5.0 and obsolete in 5.1

The long history: Continue using QPointer

[jiveaxe]

Thank you both