Dynamically created tabs - destroy object when tab closed

Question

I am dynamically creating multiple tabs, and I was wondering if when I close the tab, does it actually destroy the object?

I have set the attribute of the dynamically created tab to QtCore.Qt.WA_DeleteOnClose

I assume that setting the attribute doesn't do anything because the closeEvent isn't called on it.

    self.tabWidget.tabCloseRequested.connect(self.close_handler) # connect close button to slot

    def close_handler(self, index):
        'Remove added tab if applicable'
        try:
            #self.tabWidget.widget(index).deleteLater() #does this need to be added?
            self.tabWidget.removeTab(index)
        except:
            Data.logger.exception('Exception occured:')

How do I make sure that the object is being destroyed?

Answer 1

My answer is oriented to explain details that the other answer does not indicate so that you understand how it handles the memory Qt.

If you want to know if a QObject is eliminated then you must use the destroyed signal.

If you want to delete a QObject you must use the deleteLater() method.

In the case of the elimination of a widget added to the QTabWidget this will notify the QTabBar that it will be deleted so there are no problems of accessing non-reserved memory.

Considering the above, a possible solution is:

def close_handler(self, index):
    widget = self.tabWidget.widget(index)
    widget.deleteLater()

You can check it with the following example:

from PyQt5 import QtCore, QtGui, QtWidgets, QtWebEngineWidgets


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        self.tabWidget = QtWidgets.QTabWidget(tabsClosable=True)
        self.tabWidget.tabCloseRequested.connect(self.onTabCloseRequested)
        self.setCentralWidget(self.tabWidget)

        for i in range(10):
            widget = QtWidgets.QWidget()
            widget.destroyed.connect(
                lambda obj: print(
                    "deleted {}, count: {}".format(obj, self.tabWidget.count())
                )
            )
            self.tabWidget.addTab(widget, "Tab %s" % (i))

    @QtCore.pyqtSlot(int)
    def onTabCloseRequested(self, index):
        widget = self.tabWidget.widget(index)
        widget.deleteLater()


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.resize(640, 480)
    w.show()
    sys.exit(app.exec_())

As you can see, it is not necessary to use the attribute Qt::WA_DeleteOnClose, but if you use it, it would be enough to close the widget.

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        self.tabWidget = QtWidgets.QTabWidget(tabsClosable=True)
        self.tabWidget.tabCloseRequested.connect(self.onTabCloseRequested)
        self.setCentralWidget(self.tabWidget)

        for i in range(10):
            widget = QtWidgets.QWidget()
            widget.setAttribute(QtCore.Qt.WA_DeleteOnClose)
            widget.destroyed.connect(
                lambda obj: print(
                    "deleted {}, count: {}".format(obj, self.tabWidget.count())
                )
            )
            self.tabWidget.addTab(widget, "Tab %s" % (i))

    @QtCore.pyqtSlot(int)
    def onTabCloseRequested(self, index):
        widget = self.tabWidget.widget(index)
        widget.close()

It is not necessary to use removeTab() since this does not destroy the widget, that method is thought so that when you want to place the widget removed to another widget.