CODE EXAMPLE FOR CPP

QMetaObject_invokeMethod

#ifndef CALLER_H
#define CALLER_H

#include <QObject>
#include <QMap>
#include <utility>
#include <map>

#include "receiver.h"
#define CALL_MEMBER_FN(object,ptrToMember)  ((object)->*(ptrToMember))
typedef void (Receiver::*callback)(SomeData);

class Caller : public QObject
{
    Q_OBJECT
public:
    explicit Caller(QObject *parent = nullptr) : QObject(parent) { }

    void registerCallback(int id, Receiver* receiver, callback c)
    {
        auto pair = std::make_pair(receiver, c);
        _callbackMap.emplace(id, pair);
    }

    bool call(const SomeData data)
    {
        auto &receiver = _callbackMap.at(data.id);
        return QMetaObject::invokeMethod(receiver.first, [data, receiver] () {
            // method 1
            std::invoke(receiver.second, receiver.first, data);
            // method 2 (better not to use a MACRO)
            CALL_MEMBER_FN(receiver.first, receiver.second)(data);
        }, Qt::QueuedConnection);
    }

    bool call_invoke(const SomeData data)
    {
        auto &receiver = _callbackMap.at(data.id);
        std::invoke(receiver.second, receiver.first, data);
        return true;
    }

signals:

private:
    std::map<int,std::pair<Receiver*,callback>> _callbackMap;
};

#endif // CALLER_H