QJSEngine中的访问动态特性

Question

我可以访问传递到QObject中的QJSEngine的属性，但是为什么不能访问动态属性呢？

auto myObject = new MyObject(); // Contains a single property 'myProp'.

QJSEngine engine;

auto scriptMyObject = engine.newQObject( myObject );
engine.globalObject().setProperty( "myObject" , scriptMyObject );

engine.evaluate( "myObject.myProp = 4.2" );
cout << engine.evaluate( "myObject.myProp" ).toNumber() << endl;

myObject->setProperty( "newProp", 35 );
cout << myObject->property( "newProp" ).toInt() << endl;

cout << engine.evaluate( "myObject.newProp" ).toInt() << endl;

返回：

4.2
35
0

使用QT5.2。

Answer 1

似乎是QML中的一个bug。如果你用QScriptEngine代替，问题似乎就消失了，

#include <QScriptEngine>
#include <QCoreApplication>
#include <QDebug>

int main(int a, char *b[])
{
    QCoreApplication app(a,b);
    auto myObject = new QObject;
    QScriptEngine engine;

    auto scriptMyObject = engine.newQObject( myObject );

    myObject->setProperty( "newProp", 35 );
    engine.globalObject().setProperty( "myObject" , scriptMyObject );
    qDebug() << myObject->property( "newProp" ).toInt();
    qDebug() << engine.evaluate( "myObject.newProp" ).toInteger();
    qDebug() << engine.evaluate( "myObject.newProp = 45" ).toInteger();
    qDebug() << myObject->property( "newProp" ).toInt();
    qDebug() << " -------- ";
    // still can't create new properties from JS?
    qDebug() << engine.evaluate( "myObject.fancyProp = 30" ).toInteger();
    qDebug() << myObject->property("fancyProp").toInt();

    return 0;
}

结果：

35
35
45
45
 -------- 
30
0

因此，这看起来像QJSEngine中的一个bug，因为bahaviour与QScriptEngine不同。