Signal Slot Mechanism Error

[star673]

Hello all,

I would like to make signal slot mechanism between two seperate classes. I have created "Bicycle" and "Car" classes. Here the codes.

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "car.h"
#include "bicycle.h"


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
;

    car = new Car();
    bicycle = new Bicycle();


    connect(bicycle,&Bicycle::bicycleSignal(),car,&Car::carSlot());
}



MainWindow::~MainWindow()
{
    delete ui;
}

Classes are defined like below.

#ifndef CAR_H
#define CAR_H

#include <QObject>

class Car : public QObject
{
    Q_OBJECT
public:
    explicit Car(QObject *parent = nullptr);


signals:
    void carSignal();


public slots:
    void carSlot();
};

#endif // CAR_H

#ifndef BICYCLE_H
#define BICYCLE_H

#include <QObject>

class Bicycle : public QObject
{
    Q_OBJECT
public:
    explicit Bicycle(QObject *parent = nullptr);

signals:
    void bicycleSignal();

public slots:
    void bicycleSlot();
};

#endif // BICYCLE_H

I have created the instances belong to Car and Bicycle classes. I got an error like " cannot call member function ‘void Bicycle::bicycleSignal()’ without object
connect(bicycle,&Bicycle::bicycleSignal(),car,&Car::carSlot());
^"

How can I solve this issue?

[JonB]

@star673

connect(bicycle,&Bicycle::bicycleSignal(),car,&Car::carSlot());

Just by reading what the syntax for connect() tells/shows you what to write for the signal & slot methods. It does not tell you to put trailing () on those function references.

[star673]

@JonB

I couldn't just recognize it. Thank you.