Qt Creator - cannot connect signal to slot (no matching function for call to)

Question

I'm writing to write a simple signal-slot connect function in Qt Creator (Qt5.1). Here is (part of) my code for this.

linkports.h

#ifndef LINKPORTS_H
#define LINKPORTS_H
#include "portconfig.h"

class LinkPorts
{
public:
    LinkPorts();
    PortConfig ports[16];
    void enabledChangeEmit(int port, bool value);
signals:
    void enabledChanged(int port, bool value);
};

#endif // LINKPORTS_H

linkports.cpp [function definition]

void LinkPorts::enabledChangeEmit(int port, bool value) {
    emit enabledChanged();
}

linkcontrol.h [slot definition]

private slots:
    void updateEnabled(int port, bool value);

linkcontrol.cpp [connect and slot def]

LinkControl::LinkControl(QWidget *parent) :
QMainWindow(parent),
    ui(new Ui::LinkControl)
{
    ui->setupUi(this);
    connect(hardware, SIGNAL(enabledChanged(int, bool)), this, SLOT(updateEnabled(int, bool)));
    portSliders[16] = {ui->slider1, ui->slider2, ui->slider3, ui->slider4, ui->slider5, ui->slider6, ui->slider7, ui->slider8, ui->slider9, ui->slider10, ui->slider11, ui->slider12, ui->slider13, ui->slider14, ui->slider15, ui->slider16, };
}


void LinkControl::updateEnabled(int port, bool value)
{
    this->portSliders[port]->setEnabled(value);
}

And I get the error:

/home/narendran/QtWorkspace/LinkControl/linkcontrol.cpp:17: error: no matching function for call to 'LinkControl::connect(LinkPorts*&, const char*, LinkControl* const, const char*)'
     connect(hardware, SIGNAL(enabledChanged(int, bool)), this, SLOT(updateEnabled(int, bool)));

Some help would really be appreciated, thank you.

By the way, I define hardware as a LinkPorts object using:

LinkPorts *hardware = new LinkPorts();

in a global objects file.

Kosovan · Accepted Answer · 2014-09-29T19:04:23.893

2

Only subclasses of QObject with Q_OBJECT macro can use signals and slots mechanism in Qt

#include <QObject>

class LinkPorts : public QObject
{
    Q_OBJECT
public:

Moreover, if you want send some data with signal you should use next:

void LinkPorts::enabledChangeEmit(int port, bool value) {
    emit enabledChanged(port, value);
}

edited Sep 29 '14 at 19:04

answered Sep 29 '14 at 18:52

Kosovan

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Thank you! The solution did not directly work, but a quick search returned this: http://www.qtforum.org/article/20222/what-means-qobject-is-an-inaccessible-base-of-myobject.html With the public before the QObject in the subclass definition, it works. – Narendran Muraleedharan Sep 29 '14 at 19:02
@NarendranMuraleedharan Exuse me, it was just a typo. By default compiler set the private inheritance, so it is really couldn't work properly, but I fixed it already. – Kosovan Sep 29 '14 at 19:06

Qt Creator - cannot connect signal to slot (no matching function for call to)

1 Answers1