[FIXED] Connect to DBus signal - Correct syntax - PySide6

Issue

can you help me with the correct syntax to connect to a DBus signal?

This is one of my many tries which at least runs and matches the signature in the docs:

from PySide6 import QtDBus
from PySide6.QtCore import Q
from PySide6.QtWidgets import QMainWindow

class MainWindow(QMainWindow):
    __slots__ = ["__mainwidget"]
    __mainwidget:QWidget

    def __init__ (self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        service = 'org.freedesktop.DBus'
        path = '/org/freedesktop/DBus'
        iface = 'org.freedesktop.DBus'
        conn = QtDBus.QDBusConnection.systemBus()
        conn.connect(service, path, iface, "NameOwnerChanged", self, "nochangeslot")
        #smp = QtDBus.QDBusInterface(service, path, iface, connection=QtDBus.QDBusConnection.systemBus()


    def nochangeslot(self, arg:object) -> None:
        print(arg)
        pass

But it doesn't work and looks weird with the slot as string...

On the output I see:

qt.dbus.integration: Could not connect "org.freedesktop.DBus" to ochangeslot

Please consider this is a PySide6 issue and not a PyQt5 issue, the signature of the call is slightly different and my code doesn't hang like in similar topics on stackoverflow.

Thank you in advance for any help!

Solution

This es the full solution to my initial post, I got this running with the QT/PySide support and they also acknowledged the hangig bug and a Python crash:

import sys
from PySide6.QtWidgets import QMainWindow
from PySide6 import QtDBus, QtCore
from PySide6.QtCore import QLibraryInfo, qVersion, Slot
from PySide6.QtWidgets import QApplication, QMainWindow

class MainWindow(QMainWindow):

    def __init__ (self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        service = "org.freedesktop.DBus"
        path = "/org/freedesktop/DBus"
        iface = "org.freedesktop.DBus"
        conn = QtDBus.QDBusConnection.systemBus()

        #without this, the conn.connect call hangs, seems to be a bug, is already reported and fixed.
        conn.registerObject('/', self)

        conn.connect(service, path, iface, "NameOwnerChanged", self, QtCore.SLOT("nameownerchanged(QString, QString, QString)"))    
        pass

    @Slot(str, str, str)
    def nameownerchanged(self, arg1:str, arg2:str, arg3:str) -> None:
        print(arg1)
        print(arg2)
        print(arg3)
        pass

if __name__ == '__main__':
    print('Python {}.{}.{} {}'.format(sys.version_info[0], sys.version_info[1],
                                       sys.version_info[2], sys.platform))
    print(QLibraryInfo.build())
    app = QApplication(sys.argv)
    window = MainWindow()
    window.setWindowTitle(qVersion())
    window.resize(800, 480)
    window.show()
    sys.exit(app.exec())

Answered By - Drexel