c++ - QQmlListReference：如何使用 QQmlListProperty 属性

Question

我想使用QQmlListReference来操作QQmlListProperty，这似乎正是它的用途。但即使在一个最小的例子中，我也无法构造一个有效的QQmlListReference.

自包含示例：

// demo.cpp                                                                                                                                                                                   
#include <QQmlListProperty>                                                                                                                                                                   
#include <QQmlListReference>                                                                                                                                                                  
#include <QtTest>                                                                                                                                                                             
                                                                                                                                                                                              
class Demo : public QObject                                                                                                                                                                   
{                                                                                                                                                                                             
    Q_OBJECT                                                                                                                                                                                  
    Q_PROPERTY(QQmlListProperty<QObject> prop READ prop)                                                                                                                                      
                                                                                                                                                                                              
    QList<QObject*> m_list;                                                                                                                                                                   
                                                                                                                                                                                              
public:                                                                                                                                                                                       
    QQmlListProperty<QObject> prop() { return {this, &m_list}; }                                                                                                                              
};                                                                                                                                                                                            
                                                                                                                                                                                              
class TestDemo : public QObject                                                                                                                                                               
{                                                                                                                                                                                             
    Q_OBJECT                                                                                                                                                                                  
                                                                                                                                                                                              
private slots:                                                                                                                                                                                
    void testProp() {                                                                                                                                                                         
        Demo demo;                                                                                                                                                                            
        QQmlListReference ref(&demo, "prop");                                                                                                                                                 
        QVERIFY(ref.isValid()); // <= fails here                                                                                                                                              
    }                                                                                                                                                                                         
};                                                                                                                                                                                            
                                                                                                                                                                                              
QTEST_APPLESS_MAIN(TestDemo)                                                                                                                                                                  
                                                                                                                                                                                              
#include "demo.moc"                                                                                                                                                                           

而CMakeLists, 只是为了完整性：

# CMakeLists.txt                                                                                                                                                                              
cmake_minimum_required(VERSION 3.13)                                                                                                                                                          
project(demo LANGUAGES CXX)                                                                                                                                                                   
find_package(Qt5 COMPONENTS Qml Test)                                                                                                                                                         
add_executable(demo demo.cpp)                                                                                                                                                                 
set_property(TARGET demo PROPERTY AUTOMOC ON)                                                                                                                                                 
target_link_libraries(demo PRIVATE Qt5::Qml Qt5::Test)                                                                                                                                        

关于我做错了什么的任何建议？