Qt如何将消息在2个没有关系的类中从一个类发送到另一个类中

条件：

①2个类直接没有任何关系；

②接收消息的类必须有一个全局变量；

③ QMetaObject::invokeMethod((QObject*)全局变量类, "接收的方法", Qt::AutoConnection, Q_ARG(接收的参数类型, 接收的参数));

class ViewManagerA : public QMainWindow

{

    Q_OBJECT   

public:

    ViewManagerA(QWidget *parent = 0);

    ~ViewManagerA();

private slots:

    //界面点击事件处理

    void receiveMsg(QString msg);

}

ViewManager *g_viewManagerA;

extern ViewManager *g_viewManagerA;

class ViewManagerB : public QObject

{

    Q_OBJECT   

public:

    ViewManagerB(QWidget *parent = 0);

    ~ViewManagerB();

 private:
    void sendMsg();

}

void ViewManagerB::sendMsg()

{

   QMetaObject::invokeMethod((QObject*)g_viewManagerA, "receiveMsg", Qt::AutoConnection, Q_ARG(QString, "测试"));

}