Remove tab from tabwidget containing listview and model

[johan Borgström]

Hi,

I am using a tabwidget and on each tab I am creating a listview with a standard model. My question is how do I make sure when I delete the tabs that everything gets deleted, including the model. As far as I understand if you delete the parent widget the children will also be deleted.

Below you will find a simplified version of what I am creating. Should I "manually" deleting the model?

Thankful for all comments and feedback!

BR,

Johan

import sys

from PySide2 import QtGui, QtCore, QtWidgets

from maya import OpenMayaUI as omui

from shiboken2 import wrapInstance

from functools import partial

class TabWidget(QtWidgets.QWidget):

    

    def __init__(self, parent=None):

        super(TabWidget, self).__init__(parent) 

        self.setWindowFlags(QtCore.Qt.Tool)

        self.setGeometry(50, 200, 300, 300)

        self.setWindowTitle('Tabwidget')

        vbox = QtWidgets.QVBoxLayout(self)

        self.tab_widget = QtWidgets.QTabWidget()

        vbox.addWidget(self.tab_widget)

        label_list = ['A', 'B', 'C']

        # add tabs

        add_tabs_button = QtWidgets.QPushButton('Add Tabs')

        add_tabs_button.clicked.connect(partial(self.add_tabs, label_list))

        vbox.addWidget(add_tabs_button)

        # remove tabs

        remove_tabs_button = QtWidgets.QPushButton('Remove Tabs')

        remove_tabs_button.clicked.connect(self.remove_tabs)

        vbox.addWidget(remove_tabs_button)

    def remove_tabs(self):

        #self.tab_widget.clear()

        for i in range(self.tab_widget.count()):

            #print self.tab_widget.removeTab(0)

            self.tab_widget.widget(i).deleteLater()

    def add_tabs(self, label_list):

        for label in label_list:

            widget = QtWidgets.QWidget()

            self.tab_widget.addTab(widget, label)

            vbox = QtWidgets.QVBoxLayout(widget)

            model = QtGui.QStandardItemModel()

            for i in range(5):

                model.appendRow(QtGui.QStandardItem('{} {}'.format(label, i)))

            list_view = QtWidgets.QListView()

            list_view.setModel(model)

            vbox.addWidget(list_view)

def show():

    mayaMainWindow = wrapInstance(long(omui.MQtUtil.mainWindow()), QtWidgets.QWidget)     

    win = TabWidget(parent=mayaMainWindow)

    win.show()

    return win

[Marcus Ottosson]

I got curious about this, had a peek at the docs and found this.

The view does not take ownership of the model unless it is the model’s parent object because the model may be shared between many different views.

In your case, the model remains parent-less, which means it does not automatically get cleaned up. Having said that, it’s possible, even likely, that Python’s garbage collection takes care of it, since it will no longer be referenced anywhere.

You can use the Python module gc to find out.

• https://pymotw.com/2/gc/

Also from the docs, it says..

If both the old model and the old selection model do not have parents, or if their parents are long-lived objects, it may be preferable to call their deleteLater() functions to explicitly delete them.

So if you’d rather not find out explicitly, deleting it yourself isn’t a terrible idea.

• https://doc.qt.io/qt-5/qabstractitemview.html#setModel

​

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[johan Borgström]

Hi Marcus,

Thanks for your feedback. I decided to create a separate class for the widget that are used in the tab widget, and when that widget is deleted run a function to cleanup the model. Not sure if this is the "proper" way to do it. I have not yet tried the pymotw to inspect the gc, will look into that. 

BR,

Johan

import sys

from PySide2 import QtGui, QtCore, QtWidgets

from maya import OpenMayaUI as omui

from shiboken2 import wrapInstance

from functools import partial

class ListWidget(QtWidgets.QWidget):

    def __init__(self, parent=None):

        super(ListWidget, self).__init__(parent) 

        vbox = QtWidgets.QVBoxLayout(self)

        self.model = QtGui.QStandardItemModel()

        self.list_view = QtWidgets.QListView()

        self.list_view.setModel(self.model)

        vbox.addWidget(self.list_view)

        self.destroyed.connect(partial(ListWidget._on_destroyed, self.model))

    def populate_list(self, name_list):

        for name in name_list:

            self.model.appendRow(QtGui.QStandardItem(name))

    @staticmethod

    def _on_destroyed(model):

       #print model

       model.deleteLater()

class TabWidget(QtWidgets.QWidget):

    

    def __init__(self, parent=None):

        super(TabWidget, self).__init__(parent) 

        self.setWindowFlags(QtCore.Qt.Tool)

        self.setGeometry(50, 200, 300, 300)

        self.setWindowTitle('Tabwidget')

        vbox = QtWidgets.QVBoxLayout(self)

        self.tab_widget = QtWidgets.QTabWidget()

        vbox.addWidget(self.tab_widget)

        label_list = ['A', 'B', 'C']

        # add tabs

        add_tabs_button = QtWidgets.QPushButton('Add Tabs')

        add_tabs_button.clicked.connect(partial(self.add_tabs, label_list))

        vbox.addWidget(add_tabs_button)

        # remove tabs

        remove_tabs_button = QtWidgets.QPushButton('Remove Tabs')

        remove_tabs_button.clicked.connect(self.remove_tabs)

        vbox.addWidget(remove_tabs_button)

    def remove_tabs(self):

        for i in range(self.tab_widget.count()):

            self.tab_widget.widget(i).deleteLater()

    def add_tabs(self, label_list):

        for label in label_list:

            list_widget = ListWidget()

            list_widget.populate_list([ '{} {}'.format(label, n) for n in range(5)])

            self.tab_widget.addTab(list_widget, label)

def show():

    mayaMainWindow = wrapInstance(long(omui.MQtUtil.mainWindow()), QtWidgets.QWidget)     

    win = TabWidget(parent=mayaMainWindow)

    win.show()

    return win

[Marcus Ottosson]

Out of curiosity, how come you can't parent your model to your widget, and let Qt handle memory management?​

[johan Borgström]

Good question :)

That is probably the easiest thing to do, thanks!