QT6 源（2）：由类方法 QOBject :: metaObject（）得到类 QMetaObject，宏 Q_OBJET，类 QObject 的源码注释整理（删除了还没学到的）

本文链接：https://blog.youkuaiyun.com/zhangzhangkeji/article/details/147157226

（1）在 QT 里任何类都继承于 QObject 类，以继承大师们的代码，并借助于大师们的原有代码，来完成对象的析构与内存回收。与此同时，还有几个关键的类，也会被使用，现在根据它们的源码来学习它们。磨刀不误砍柴工。只有更好的了解了这些代码后，借助于以前大师们的劳动成果，才可以更流利地，写出更稳健的 QT 代码，知其然，知其所以然。
第一个要学习的类是 QMetaObject 。它的引出位置如下：

（2）由类 QObject 的成员函数 QObject :: metaObject ( ) 引出类 QMetaObject ：

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（3）引出宏 Object 的源代码，看看其提供了哪些功能：

/* qmake ignore Q_OBJECT */
#define Q_OBJECT \
public: \
    QT_WARNING_PUSH \
    Q_OBJECT_NO_OVERRIDE_WARNING \
    static const QMetaObject staticMetaObject; \
    virtual const QMetaObject *metaObject() const; \
    virtual void *qt_metacast(const char *); \
    virtual int qt_metacall(QMetaObject::Call, int, void **); \
    QT_TR_FUNCTIONS \
private: \
    Q_OBJECT_NO_ATTRIBUTES_WARNING \
    Q_DECL_HIDDEN_STATIC_METACALL static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **); \
    QT_WARNING_POP \
    struct QPrivateSignal {}; \
    QT_ANNOTATE_CLASS(qt_qobject, "")

++分析该宏 QOBJECT 提供了哪些功能 ：

在这里插入图片描述

（3） 由此得出类 QObject 的数据结构 ：

在这里插入图片描述

（4）类 QObject 的简化版源码：

class Q_CORE_EXPORT QObject
{
    Q_OBJECT

    Q_PROPERTY(QString objectName  //定义了 objectName 属性 
    		READ objectName 
    		WRITE setObjectName 
    		NOTIFY objectNameChanged
            BINDABLE bindableObjectName)
    Q_DECLARE_PRIVATE(QObject)     // 声明私有类

public:
    Q_INVOKABLE explicit QObject(QObject *parent = nullptr);
    virtual ~QObject();

    template<typename T> //查找容器中孩子
    inline T findChild(const QString &aName = QString(),  //定义略
    	Qt::FindChildOptions options = Qt::FindChildrenRecursively) const { }

    template<typename T>
    inline QList<T> findChildren(const QString &aName = QString(), 
    	Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
    {  QList<T> list;  return list;   }

#if QT_CONFIG(regularexpression)
    template<typename T>  // 
    inline QList<T> findChildren(const QRegularExpression &re, 
    	Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
    { QList<T> list; return list;    }
#endif // QT_CONFIG(regularexpression)

	//typedef QList<QObject *> QObjectList;
    inline const QObjectList &children() const { return d_ptr->children; }

    void setParent(QObject *parent); //此函数定义在这里，加入容器

    static QMetaObject::Connection connect(
    	const QObject * sender  , const char * signal,
        const QObject * receiver, const char * member, 
        Qt::ConnectionType = Qt::AutoConnection);

    static QMetaObject::Connection connect( //这俩是类的静态成员函数
    	const QObject * sender  , const QMetaMethod & signal,
        const QObject * receiver, const QMetaMethod & method,
        Qt::ConnectionType type = Qt::AutoConnection);

    inline QMetaObject::Connection connect( //基于对象的动态成员函数
    	const QObject * sender, const char * signal,
        const char    * member, 
        Qt::ConnectionType type = Qt::AutoConnection) const;

    static bool disconnect( //解除信号与槽的静态成员函数
    	const QObject * sender  , const char * signal,
        const QObject * receiver, const char * member);
    static bool disconnect(
    	const QObject * sender  , const QMetaMethod &signal,
        const QObject * receiver, const QMetaMethod &member);
        
    inline bool disconnect( //动态函数默认由信号发送者调用
    							  const char * signal = nullptr,
        const QObject *receiver = nullptr, 
        const char * member = nullptr) const
    { return disconnect(this, signal, receiver, member); }
    
    inline bool disconnect(
    	const QObject * receiver, 
    	const char * member = nullptr) const
    { return disconnect(this, nullptr, receiver, member); }
    
    static bool disconnect(const QMetaObject::Connection &);

    void dumpObjectTree() const;
    void dumpObjectInfo() const;

#ifndef QT_NO_PROPERTIES  //这里出现了动态属性设置
    bool setProperty (const char * name, const QVariant &value);
    QVariant property(const char * name) const; //根据属性名获取属性值,形参是字符串
    //作为对比 QMetaProperty QMetaObject::property(int index) const;
    //根据属性索引返回值属性对象 QMetaProperty对象,形参是数字索引
    QList<QByteArray> dynamicPropertyNames() const;
    QBindingStorage *bindingStorage() { return &d_ptr->bindingStorage; }
    const QBindingStorage *bindingStorage() const { return &d_ptr->bindingStorage; }
#endif // QT_NO_PROPERTIES

Q_SIGNALS:
    void destroyed(QObject * = nullptr); //信号函数不需要实现
    void objectNameChanged(const QString &objectName, QPrivateSignal);

public: //显示本对象所在的容器，或者说返回容器父类
    inline QObject * parent() const { return d_ptr->parent; }
	//而  QMetaObject :: superClass() 则返回继承父类 

	//用于判断本对象是否是形参类及其子类的实现 
    inline bool inherits(const char * classname) const
    {  return const_cast<QObject *>(this)->qt_metacast(classname) != nullptr;  }
	//bool QMetaObject :: inherits(const QMetaObject * metaObject) 用于判断类的继承关系

public Q_SLOTS:
    void deleteLater();

protected:
    QObject * sender() const; //判断信号的发送者
    int senderSignalIndex() const;
    int receivers(const char *signal) const;
    bool isSignalConnected(const QMetaMethod &signal) const;

protected:
    QObject(QObjectPrivate &dd, QObject *parent = nullptr);

protected: //定义了本类的数据成员
    QScopedPointer<QObjectData> d_ptr;

    friend struct QMetaObject; //定义本类的友元类
    friend struct QMetaObjectPrivate;
    friend class QMetaCallEvent;
    friend class QApplication;
    friend class QApplicationPrivate;
    friend class QCoreApplication;
    friend class QCoreApplicationPrivate;
    friend class QWidget;
    friend class QAccessibleWidget;
    friend class QThreadData;

private:
    Q_DISABLE_COPY(QObject) //禁止对本类的复制操作
    Q_PRIVATE_SLOT(d_func(), void _q_reregisterTimers(void *))
};