Doc: Update QQmlContext documentation to discourage context properties

The snippets showing the use of setContextProperty() are intentionally
removed. You should not do such a thing.

Pick-to: 6.5
Fixes: QTBUG-106030
Change-Id: I1c5c217630aee8dd6e44f9f244b9ef2a8d2ef290
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 104 insertions, 0 deletions

diff --git a/src/qml/doc/snippets/qml/exposing-state/RequiredProperties.qml b/src/qml/doc/snippets/qml/exposing-state/RequiredProperties.qml
new file mode 100644
index 0000000000..18425930de
--- /dev/null
+++ b/src/qml/doc/snippets/qml/exposing-state/RequiredProperties.qml
@@ -0,0 +1,23 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+//![0]
+pragma ComponentBehavior: Bound
+
+import QtQuick
+
+Window {
+    id: root
+    visible: true
+
+    required property int thing
+
+    Text {
+        anchors.fill: parent
+        text: "The thing is " + root.thing
+    }
+
+    component Inner: QtObject {
+        objectName: "I can see " + root.thing + " because I'm bound."
+    }
+}
+//![0]
diff --git a/src/qml/doc/snippets/qml/exposing-state/createWithInitialProperties.cpp b/src/qml/doc/snippets/qml/exposing-state/createWithInitialProperties.cpp
new file mode 100644
index 0000000000..1e5f1859f9
--- /dev/null
+++ b/src/qml/doc/snippets/qml/exposing-state/createWithInitialProperties.cpp
@@ -0,0 +1,23 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QtQml/qqml.h>
+#include <QtQml/qqmlengine.h>
+#include <QtQml/qqmlcomponent.h>
+#include <QtGui/qguiapplication.h>
+
+int main(int argc, char *argv[])
+{
+    QGuiApplication app(argc, argv);
+
+//![0]
+    QQmlEngine engine;
+
+    QQmlComponent component(&engine, "MyModule", "RequiredProperties");
+    QScopedPointer<QObject> o(component.createWithInitialProperties({
+            {"thing", 11}
+    }));
+//![0]
+
+    return app.exec();
+}
diff --git a/src/qml/doc/snippets/qml/exposing-state/singleton.h b/src/qml/doc/snippets/qml/exposing-state/singleton.h
new file mode 100644
index 0000000000..e600531883
--- /dev/null
+++ b/src/qml/doc/snippets/qml/exposing-state/singleton.h
@@ -0,0 +1,49 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef SINGLETON_H
+#define SINGLETON_H
+
+#include <QtQml/qobject.h>
+#include <QtQml/qqml.h>
+#include <QtQml/qqmlengine.h>
+
+//![0]
+// Singleton.h
+class Singleton : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(int thing READ thing WRITE setThing NOTIFY thingChanged FINAL)
+    QML_ELEMENT
+    QML_SINGLETON
+
+public:
+    Singleton(QObject *parent = nullptr) : QObject(parent) {}
+
+    int thing() const { return m_value; }
+    void setThing(int v)
+    {
+        if (v != m_value) {
+            m_value = v;
+            emit thingChanged();
+        }
+    }
+
+signals:
+    void thingChanged();
+
+private:
+    int m_value = 12;
+};
+//![0]
+
+inline void setTheThing(QQmlEngine *engine)
+{
+//![1]
+    Singleton *singleton
+            = engine->singletonInstance<Singleton *>("MyModule", "Singleton");
+    singleton->setThing(77);
+//![1]
+}
+
+#endif
diff --git a/src/qml/doc/snippets/qml/exposing-state/useSingleton.qml b/src/qml/doc/snippets/qml/exposing-state/useSingleton.qml
new file mode 100644
index 0000000000..a9021a9241
--- /dev/null
+++ b/src/qml/doc/snippets/qml/exposing-state/useSingleton.qml
@@ -0,0 +1,9 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+//![0]
+import QtQml
+
+QtObject {
+    objectName: "The thing is " + Singleton.thing
+}
+//![0]