属性的QVariant(QString，“”)在属性系统中是什么意思？

Question

QObject子类有一个返回QMetaObject对象的函数。该函数是metaObject()。我使用这个方法来获取它：

    MyObject *myObject_1=new MyObject;
   const QMetaObject *metaobject=myObject_1->metaObject();

当你使用这段代码时，它会打印类似下面这样的内容。

Object.h

#ifndef MYOBJECT_H
#define MYOBJECT_H

#include <QObject>

class MyObject:public QObject
{
   Q_OBJECT
public:
   MyObject(QObject *parent=0):QObject(parent){

   }
};

#endif // MYOBJECT_H

Main.cpp

#include "myobject.h"
#include <QApplication>
#include <QMetaObject>
#include <QMetaProperty>
#include <QDebug>

int main(int argc, char *argv[])
{
   MyObject *myObject_1=new MyObject;
   const QMetaObject *metaobject=myObject_1->metaObject();
   for(int i=0;i<metaobject->propertyCount();i++){
       QMetaProperty metaproperty=metaobject->property(i);
       qDebug()<<myObject_1->property(metaproperty.name());
   }

   return 0;
}

打印结果：

​

​

当你使用这段代码时，它会打印类似下面这样的内容。

Object.h

#ifndef MYOBJECT_H
#define MYOBJECT_H

#include <QObject>

class MyObject:public QObject
{
   Q_OBJECT
   Q_PROPERTY(Priority priority READ priority WRITE setPriority)
public:
   enum Priority{One,Two,Three};
   Q_ENUM(Priority)
   MyObject(QObject *parent=0):QObject(parent){

   }
   void setPriority(Priority priority){
       m_priority=priority;
   }

   Priority priority()const{
       return m_priority;
   }
private:
   Priority m_priority;
};

#endif // MYOBJECT_H

Main.cpp

#include "myobject.h"
#include <QApplication>
#include <QMetaObject>
#include <QMetaProperty>
#include <QDebug>

int main(int argc, char *argv[])
{
   MyObject *myObject_1=new MyObject;
   myObject_1->setProperty("priority","Two");
   const QMetaObject *metaobject=myObject_1->metaObject();
   for(int i=0;i<metaobject->propertyCount();i++){
       QMetaProperty metaproperty=metaobject->property(i);
       qDebug()<<myObject_1->property(metaproperty.name());
   }

   return 0;
}

打印结果

​

​

问题是为什么myObject_1有一个QVariant(QString，“”)属性？属性的QVariant(QString，“”)在属性系统中是什么意思？

查看断点：

​

​

Answer 1

您已经打印了基类- QObject中的属性。使用propertyOffset仅显示派生类的属性：

  //                          \/ 
  for(int i=metaobject->propertyOffset();i<metaobject->propertyCount();i++){
       QMetaProperty metaproperty=metaobject->property(i);
       qDebug()<<myObject_1->property(metaproperty.name());
   }

此属性QVariant(QString,“”)是基类的对象名称。