在QML

Question

分配null以C++類的QObject *屬性時，我去掉下面的一行時斷言失敗，我得到一個斷言：

ASSERT：！」 from.isNull（）& & to.isNull （）」在文件[...] \ qtdeclarative \ SRC \ QML \ QML \ qqmlpropertycache.cpp，線1586

#include <QGuiApplication> 
#include <QtQml> 
#include <QtQuick> 

class Inventory : public QObject 
{ 
    Q_OBJECT 
public: 
    Inventory() { 
    } 
}; 

class InventoryModel : public QObject 
{ 
    Q_OBJECT 
    Q_PROPERTY(Inventory *inventory READ inventory WRITE setInventory NOTIFY inventoryChanged) 
public: 
    InventoryModel() : mInventory(0) { 
    } 

    Inventory *inventory() const { 
     return mInventory; 
    } 

    void setInventory(Inventory *inventory) { 
     if (inventory != mInventory) { 
      mInventory = inventory; 
      emit inventoryChanged(); 
     } 
    } 
signals: 
    void inventoryChanged(); 
private: 
    Inventory *mInventory; 
}; 

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

// qRegisterMetaType<Inventory*>(); 
    qmlRegisterType<InventoryModel>("Qml", 1, 0, "InventoryModel"); 

    QQmlApplicationEngine engine; 
    engine.load(QUrl(QStringLiteral("qrc:///main.qml"))); 

    return app.exec(); 
} 

#include "main.moc" 

main.qml：

import QtQuick 2.3 
import QtQuick.Controls 1.2 

import Qml 1.0 

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

    InventoryModel { 
     inventory: null 
    } 
} 

我在用Qt 5.4編譯（qt聲明是在f9ee33f9683a4cd4d1a2e41efa6e8d124e9d731d）。任何想法可能會造成這種情況？

Answer 1

嘗試qmlRegisterType代替：

qmlRegisterType<Inventory>("Qml", 1, 0, "Inventory"); 

斷言可能尚未公佈，爲9月6日的與此有關bug