Use different instances with qobject

Jeronimo

Hi i am trying to use different instances using the follow code:

QObject::connect(&Downloader::instance(),&Downloader::testSignal,{ });

But show me the follow error:
error: C2664: 'QMetaObject::Connection QObject::connect(const QObject *,const char *,const char ,Qt::ConnectionType) const' : el argumento 2 no puede convertirse de 'void (__thiscall Downloader:: )(void)' a 'const char *'
conversion not possible

But this happen because i'm not using lambda thing so i cant call different instances.

? Offline

Hi! Hard to tell, but looks like some problem with a static QObject to me.

SGaist

Hi,

What is instance() supposed to return ?

Jeronimo

@SGaist it's only that i can't use differente instance i need to use "" lambda thing.

SGaist

You're using a singleton which goal is to have only one instance.

If you want several instances of your downloader then don't use a singleton.

Jeronimo

This post is deleted!

Jeronimo

@SGaist Ok i understand but i have one question:
I need to use qobject but without singletone to use my other class. sorry if i repeat the code but it's other question with the same code. The question if i can use class outside with qobject and download some files of my webpage without use one only instance. Not necessary solution only some idea thx.
Code:
Main.cpp:

#include <QCoreApplication>
#include <QDebug>
#include "downloader.h"
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QObject::connect(&Downloader::instance(),&Downloader::testSignal,
                        [](){
         QString s="http://myweb/currxml.php";

       });
    return a.exec();
}

download.h:

#ifndef Downloader_H
#define Downloader_H

#include <QObject>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrl>
#include <QDateTime>
#include <QFile>
#include <QDebug>
class Downloader : public QObject
{
    Q_OBJECT
    Q_DISABLE_COPY(Downloader)
public:
    static Downloader &instance();
    explicit Downloader(QObject *parent = nullptr);
    QString s;
    //virtual ~Downloader(){}

    void doSomething();
signals:

    void testSignal();

public slots:
    //void testSlot();
    void replyFinished (QNetworkReply *reply);

private:
    QNetworkAccessManager *manager;

};

#endif // Downloader_H

downloader.cpp

#include "downloader.h"
#include <QDebug>


Downloader &Downloader::instance()
{
    static Downloader _instance;
    return _instance;
}

Downloader::Downloader(QObject *parent) : QObject(parent)
{
    doSomething();
}

void Downloader::doSomething()
{
   //emit testSignal();
    qDebug() << "It's working!!!!";
    manager = new QNetworkAccessManager(this);
    manager->get(QNetworkRequest(QUrl(s)));
    emit instance().testSignal();
}

void Downloader::replyFinished (QNetworkReply *reply)
{
    if(reply->error())
    {
        qDebug() << "ERROR!";
        qDebug() << reply->errorString();
    }
    else
    {
        //qDebug() << reply->header(QNetworkRequest::ContentTypeHeader).toString();
        //qDebug() << reply->header(QNetworkRequest::LastModifiedHeader).toDateTime().toString();
        //qDebug() << reply->header(QNetworkRequest::ContentLengthHeader).toULongLong();
        //qDebug() << reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        //qDebug() << reply->attribute(QNetworkRequest::HttpReasonPhraseAttribute).toString();
        QString p = reply->request().url().fileName();
        QFile *file = new QFile("C:/Users/moh/"+p);
        if(file->open(QFile::Append))
        {
            file->write(reply->readAll());
            file->flush();
            file->close();
        }
        delete file;
    }

    reply->deleteLater();
}

SGaist

You won't see the signal because it's going to be emitted before the event loop is event started.

What do you mean "use class outside with qobject" ?