1.QTimer::singleShot How to transmit reference

        QString p = "pink";
        QTimer::singleShot(1000, this, [&,p](){
            print(p);
        }
        );
         Similarly, multiple parameters can be passed 

advantage ： You can pass in multiple parameters

2.QMetaObject::invokeMethod How to pass values with functions

    QString d = "prr";
    QMetaObject::invokeMethod(obj, [&,d](){
        obj->print(d);
    });

advantage ：

1. Don't need to rely on QObject*, const char *member, arg1, arg2,arg3 Methods

2. Object function parameter changes , When the function name changes , You can make mistakes when compiling

It's all used lamda function , however lamda The function itself will have additional memory overhead , Up to the old code 5 times , As far as possible with QString perhaps qt Self contained small variable

Construction and Deconstruction of test objects , Define the following use cases

static int sqr = 0;
class XString{
public:
    XString()
    {
        key = ++ sqr;
        qDebug() << __FUNCTION__ << __LINE__ << key;
    }
    XString(const XString &other)
    {
        key = ++ sqr;
        this->pink = other.pink;
        qDebug() << __FUNCTION__ << __LINE__ << key;
    }

    ~XString(){
        qDebug() << __FUNCTION__ << __LINE__ << key;
    }

    QString getPink() const { return pink; }
    void setPink(const QString &value){ pink = value; }

private:
    QString pink;
    int key;
};
class XObject : public QObject {
    Q_OBJECT

public:
    XObject(XString m, QObject *parent = nullptr)
        : QObject(parent),m(m) {}

    XString m;
public slots:
    void trigger(){emit signal_trgg(m);}
signals:
    void signal_trgg(XString p);
};

 Use cases 1
XString p;
p.setPink("pink");
QTimer::singleShot(1000, this, [&,p](){
    //this Function of 
}
);
 function ：
XString 18 1
XString 24 2
XString 24 3
XString 24 4
XString 24 5
~XString 28 4
~XString 28 3
~XString 28 2
~XString 28 1
~XString 28 5

 Use cases 2
XThread *thread = new XThread(this);
XString p;
p.setPink("pink");
XObject *o = new XObject(p, 0);
connect(o, SIGNAL(signal_trgg(XString)), this, SLOT(print(XString)));
connect(thread, SIGNAL(finished()), o, SLOT(deleteLater()));
QTimer::singleShot(1000, o, SLOT(trigger()));
o->moveToThread(thread);
thread->start();
 function ：
XString 18 1
XString 24 2
XString 24 3
~XString 28 2
~XString 28 1
XString 24 4
XString 24 5
~XString 28 4
~XString 28 5
~XString 28 3

 Multithreaded call 
XString d;
d.setPink("prr");
qDebug() << __LINE__ << d.getPink() << QThread::currentThreadId();
QMetaObject::invokeMethod(obj, [&,d](){
    qDebug() << __LINE__ << d.getPink() << QThread::currentThreadId();
});
 function ：
XString 18 1
63 "prr" 0x1fa0
XString 24 2
XString 24 3
XString 24 4
~XString 28 3
~XString 28 2
65 "prr" 0x27dc
~XString 28 1
~XString 28 4