How to pass a singleton to another class in qt - c++

Question

In the main.cppi'm creating a singleton type of a class to use it in qml with the following function:
qmlRegisterSingletonType<DataloopWrapper>("com.xpto.connector", 1, 0, "DataloopWrapper",&DataloopWrapper::qmlInstance);
a bit down on the main.cpp i call a function of another object where i want to call a function from that singleton
maybe something like this qmlTranslator.loadLanguage(lang, DataloopWrapper::qmlInstance); is possible?
I'm declaring QmlTranslatorclass the following way:
#ifndef QMLTRANSLATOR_H
#define QMLTRANSLATOR_H
#include <QObject>
#include <QTranslator>
#include <QQmlEngine>
#include <QGuiApplication>
class QmlTranslator : public QObject
{
Q_OBJECT
public:
QmlTranslator(QQmlEngine *engine, QGuiApplication *app);
Q_INVOKABLE void selectLanguage(QString language);
void InstallTranslator();
void loadLanguage(QString language, QObject*(QQmlEngine*,QJSEngine*) objDataloop);
virtual ~QmlTranslator();
signals:
void languageChanged();
private:
QTranslator *_translator;
QQmlEngine *_engine;
QGuiApplication *_app;
};
#endif // QMLTRANSLATOR_H
I'm not finding a way to pass DataloopWrapper::qmlInstanceas argument. At least it gives error in void loadLanguage(QString language, QObject*(QQmlEngine*,QJSEngine*) objDataloop);on the qmlTranslator definition.
From a public: Members of DataloopWrapperi have the defenition of qmlInstance, it's this:
class DataloopWrapper : public QObject, public something::DataloopCBHandler,
public something::DataloopTransferCBHandler
{
Q_OBJECT
public:
explicit DataloopWrapper(QObject *parent = nullptr);
virtual ~DataloopWrapper();
static QObject *qmlInstance(QQmlEngine *engine, QJSEngine *scriptEngine)
{
Q_UNUSED(engine);
Q_UNUSED(scriptEngine);
return new DataloopWrapper;
}

Answer 1

DataloopWrapper::qmlInstance is a function, that you need to call in order to get a pointer to a QObject.
For for any function you want to pass this object, you need to make it accept a pointer to a QObject (type QObject*), and don't forget to call DataloopWrapper::qmlInstance.
Translated into code:
class QmlTranslator : public QObject
{
...
void loadLanguage(QString language, QObject* objDataloop);
...
};
...
qmlTranslator.loadLanguage(lang, DataloopWrapper::qmlInstance(aQMLEngineObjectPointer, aQJSEnginePointer));