读/写QObject [英] Reading/writing QObjects

问题描述

我认为我可以使用 Q_PROPERTY 这样写一个 QObject > s：

  QDataStream& operator<<<（QDataStream& ds，const Object& obj）{
 for（int i = 0; i  if（obj.metaObject（） - > property（i）.isStored（& obj））{
 ds< obj.metaObject（） - > property（i）.read（& obj）; 
} 
} 
 return ds; 
} 
  

如果是这样，我不知道为什么 QObject s尚未实现该方法，因为它非常通用。但这是除了这一点。我如何读取文件？即，实现此函数？

  QDataStream& operator>>（QDataStream& ds，Object& obj）{
 return ds; 
} 
  

我想我可以用 ds。

PS：如果它不是很明显， 对象是继承自 QObject 的自定义类。

解决方案

这似乎工作。

  QDataStream& operator> ; ds，Object& obj）{
 QVariant var; 
 for（int i = 0; i  if（obj.metaObject（） - > property（i）.isStored （& obj））{
 ds>> var; 
 obj.metaObject（） - > property（i）.write（& obj，var）; 
} 
} 
 return ds; 
} 
  

感谢 Eugene 。

I think I can write a QObject like this by taking advantage of the Q_PROPERTYs:

QDataStream &operator<<(QDataStream &ds, const Object &obj) {
    for(int i=0; i<obj.metaObject()->propertyCount(); ++i) {
        if(obj.metaObject()->property(i).isStored(&obj)) {
            ds << obj.metaObject()->property(i).read(&obj);
        }
    }
    return ds;
}

Which, if that's true, I don't know why QObjects don't already have that method implemented because it's pretty generic. But that's besides the point. How would I read the file? i.e., implement this function?

QDataStream &operator>>(QDataStream &ds, Object &obj) {
    return ds;
}

I'm thinking I can somehow use ds.readBytes but how would I get the length of the property?

PS: If it wasn't obvious, Object is my custom class that inherits from QObject.

解决方案

This seems to work.

QDataStream &operator>>(QDataStream &ds, Object &obj) {
    QVariant var;
    for(int i=0; i<obj.metaObject()->propertyCount(); ++i) {
        if(obj.metaObject()->property(i).isStored(&obj)) {
            ds >> var;
            obj.metaObject()->property(i).write(&obj, var);
        }
    }
    return ds;
}

Thanks to Eugene.

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