Q_OBJECT

 

 

#define Q_OBJECT \
public: \
    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_DECL_HIDDEN_STATIC_METACALL static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **); \
    QT_WARNING_POP \
    struct QPrivateSignal {}; \
    QT_ANNOTATE_CLASS(qt_qobject, "")



#  define QT_TR_FUNCTIONS \
    static inline QString tr(const char *s, const char *c = Q_NULLPTR, int n = -1) \
        { return staticMetaObject.tr(s, c, n); } \
    QT_DEPRECATED static inline QString trUtf8(const char *s, const char *c = Q_NULLPTR, int n = -1) \
        { return staticMetaObject.tr(s, c, n); }

View Code

As is Q_OBJECT macro code; Qt which contains a meta-object system; as Metaobject (), qt_metacast (const char *), qt_metacall (QMetaObject :: Call, int, void **); TR, trUtf8 () function and the like;

When the program is compiled, you will see generated by the moc tool moc_xxx.cpp file; this function includes the definition of variables to achieve the function of Q_OBJECT inside the statement, as well as declarations;

 

Which, qt_metacast (const char * _clname) with qt_metacall (QMetaObject :: Call _c, int _id, void ** _ a) function is associated with signals and slots calls; and we write signal statement function is not implemented the code, However, given the corresponding moc implementation code; function code for all contain QMetaObject :: activate (this, & staticMetaObject, signal_xxx, param_list); reinterpret_cast parameters are all strongly into void * or const void * type of void * form; reinterpret_cast using a converted form the bit loss will not produce such a strong turn static_cast; i.e. stronger intensity value before turn followed is the same, but the type of variable; however const type, when the transfer of the strong adding or adding, as converted to a non-const const type type const_cast patent;