Signals and Slots, update from old to new nomenclature

Josz

Hello again,
After reading the documents, I induced that the equivalent for the next connection:

connect(tc, SIGNAL(sigCelsiusChanged(int)), ui->lcdCels, SLOT(display(int)) );

would be the next:

connect(tc, &tempconverter::sigCelsiusChanged,
            ui->lcdCels, &QLCDNumber::display);

but the compiler says:

C:\Qt\5.10.1\msvc2015\include\QtCore\qobject.h:214: candidate function not viable: no known conversion from 'void (tempconverter::*)(int) __attribute__((thiscall))' to 'const char *' for 2nd argument

please, what I did wrong?
Thanks in advance

where tc is my own objetc, here below
*.h

#ifndef TEMPCONVERTER_H
#define TEMPCONVERTER_H

#include <QObject>

class tempconverter : public QObject
{    
    Q_OBJECT

    int m_tempCelsius;

public:
    tempconverter(int tempCelsius = 0, QObject *parent = nullptr);

    //Getter Functions
    int getCelsius() const;
    int getFahrenheit() const;

public slots:
    void setCelsius(int);
    void setFahrenheit(int);

signals:
    void sigCelsiusChanged(int);
    void sigFahrenheitChanged(int);

};

#endif // TEMPCONVERTER_H

*.cpp

#include "tempconverter.h"

tempconverter::tempconverter(int tempCelsius, QObject *parent) :  QObject(parent)
{
    m_tempCelsius = tempCelsius;
}

int tempconverter::getCelsius() const
{
    return m_tempCelsius;
}

int tempconverter::getFahrenheit() const
{
    return static_cast<int>((9.0/5.0) * m_tempCelsius + 32);
}

void tempconverter::setCelsius(int tempCelsius)
{
    if (m_tempCelsius == tempCelsius) return;
    m_tempCelsius = tempCelsius;

    //emit change signal
    emit sigCelsiusChanged(m_tempCelsius);
    emit sigFahrenheitChanged(getFahrenheit());
}

void tempconverter::setFahrenheit(int tempFahrenheit)
{
     setCelsius(static_cast<int>(5.0/9.0*(tempFahrenheit - 32)));
}

VRonin

The problem is that QLCDNumber::display is overloaded, you can use:

connect(tc, &tempconverter::sigCelsiusChanged,
            ui->lcdCels,  QOverload<int>::of(&QLCDNumber::display));

See https://wiki.qt.io/New_Signal_Slot_Syntax#Overload for more infos

Josz

@VRonin Very kind of you!
Thank you very much!

JKSH

@Josz See also https://doc.qt.io/qt-5/signalsandslots-syntaxes.html for a comparison between the old and new connection syntaxes.

Josz

@JKSH Thank you