QML：如果其名称被组件本地属性遮蔽，如何访问上下文属性？

Question

My code:

main.cpp :

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>

int main(int argc, char *argv[]) {
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    engine.rootContext()->setContextProperty("text", "hey");

    return app.exec();
}

main.qml :

import QtQuick 2.5
import QtQuick.Window 2.2

Window {
    id: window
    visible: true
    width: 640
    height: 480

    Text {
        text: text
    }
}

Of course, the text: text line doesn't do what I want it to, because of name shadowing.

I worked around that by setting a property on the root object, rather than on the root context, and using text: window.text .

Is there any real fix though?

Answer 1

You don't. Using text for the name of a context property is like the worst possible choice. You'd literally do better by using blahblah . Why invite trouble?

You can implement an alias to access the context property in the root object while also exposing the root object as a dynamic scope property. This will have the advantage of still being able to use the context property while avoiding the expensive dynamic property lookup all the way down to the root , while still providing an alternative , albeit a less efficient way to get to the context property in the cases where it is shadowed.

Update: Actually there is logical reason to assume that context properties are any faster to lookup than a regular dynamic scope object property. In this aspect, the above paragraph can only be used to provide a secondary identifier to access the shadowed property.

As mentioned in the comments, a singleton will actually make the most sense in this usage context, as it is directly resolved from an import rather than involving lookups, plus you can import as which can be useful to solve name conflicts. If you want to have multiple objects exposed via a singleton, instead of exposing each one as a separate singleton you can just have the different objects members of the singleton, such can be added dynamically as properties, model items or whatever serves the particular need.