PySide6 ListProperty causes segfault?

[Keith Astoria]

I cannot get the PySide6 'ListProperty' to work correctly. I get segfaults on Ubuntu and on MacOS I get a hung Python process with no QT window displayed. I cannot test on Win10 because I cannot get PySide6 to install correctly.

This is a stripped-down example that

• Has a 'ListPropertyObj' that holds the ListProperty.
  • This is just supposed to be a simple 'list of wrapped strings'.
• Has a simple string wrapper called 'ListPropertyElement' so I have a QObject to give to the ListProperty type
• Simple ListView trying to use this ListProperty as a model.

main.py

import sys
from pathlib import Path

from typing import List

from PySide6.QtCore import QObject, Slot, Property, Signal
from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine, QmlElement, ListProperty
from PySide6.QtQuickControls2 import QQuickStyle

QML_IMPORT_NAME = "io.qt.textproperties"
QML_IMPORT_MAJOR_VERSION = 1

@QmlElement
class ListPropertyElement(QObject):
    _value: str

    def __init__(self, parent=None):
        super().__init__(parent)
        self._value = "N/A"

    def getValue(self):
        return self._value

    def setValue(self, value:str):
        self._value = value

    value = Property(str, fget=getValue, fset=setValue)

@QmlElement
class ListPropertyObj(QObject):
    
    _items: List[ListPropertyElement]

    def __init__(self, parent=None):
        super().__init__(parent)
        self._items = []

    def appendItem(self, item:ListPropertyElement):
        self._items.append(item)

    def countItems(self):
        return len(self._items)
    
    def itemAt(self, index:int):
        return self._items[index]

    items = ListProperty(ListPropertyElement,
                            count=countItems,
                            at=itemAt,
                            append=appendItem)


if __name__ == '__main__':
    app = QGuiApplication(sys.argv)
    QQuickStyle.setStyle("Material")
    engine = QQmlApplicationEngine()

    qml_file = Path(__file__).parent / 'main.qml'
    engine.load(qml_file)

    if not engine.rootObjects():
        sys.exit(-1)

    sys.exit(app.exec())

main.qml

import QtQuick 2.0
import QtQuick.Controls 2.1
import QtQuick.Window 2.1
import QtQuick.Controls.Material 2.1

import io.qt.textproperties 1.0

ApplicationWindow {
    id: page
    width: 800
    height: 400
    visible: true
    Material.theme: Material.Dark
    Material.accent: Material.Red

    ListPropertyObj {
        id: listPropertyObj

        items: [
            ListPropertyElement {
                value: "one"
            },
            ListPropertyElement {
                value: "two"
            }
        ]
    }

    ListView {
        model: listPropertyObj.items

        anchors.fill: parent

        delegate: Text {
            text: index
            color: "white"
        }
    }
}

You will note that I'm not even really accessing the list in this example. The ListView delegate is only accessing the 'index'. Perhaps I'm missing something but Google doesn't turn up much about ListProperty. Am I supposed to be using something else? If I don't try to access the ListProperty then I don't get the segfault.