SIGNAL / SLOT in QCoreApplication

ODБOï

Hi,
i did a single file (main() + a class) QCoreApplication,
i m not able to fix below error .. i feel it is about moc.

QObject::connect(task,&Task::end,// error here

please help me to understand and fix this

C:\..\main.cpp:30: erreur : undefined reference to `Task::end()'
C:\...\debug\main.o:-1: In function `ZN4TaskC1EP7QObject':
C:\...\main.cpp:10: erreur : undefined reference to `vtable for Task'
C:\...\main.o:-1: In function `ZN7QObject7connectIM4TaskFvvEPFvvEEENSt9enable_ifIXaagecvisrN9QtPrivate15FunctionPointerIT0_EE13ArgumentCountLi0EntsrSA_25IsPointerToMemberFunctionEN11QMetaObject10ConnectionEE4typeEPKNS8_IT_E6ObjectESF_PKS_S9_N2Qt14ConnectionTypeE':
C:\Qt\5.10.0\mingw53_32\include\QtCore\qobject.h:299: erreur : undefined reference to `Task::staticMetaObject'

#include <QCoreApplication>
#include <QtCore>
#include <QTcpSocket>
#include <QHostAddress>

class Task : public QObject
{
    Q_OBJECT
public:
    Task(QObject *parent = 0) : QObject(parent) {}

signals :
    void end();

public slots:
    void run()
    {  
        emit end();
    }
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    Task *task = new Task(&a);
    QObject::connect(task,&Task::end,[](){
        qDebug()<< "done.";
    });
    QTimer::singleShot(0, task, SLOT(run()));
    return a.exec();
}

Chris Kawa

Adding a Q_OBJECT macro to a class means it needs to go through the moc to generate the meta information for that class (the Task::staticMetaObject compiler complains about missing). The problem here is that by default moc is not run on cpp files, only on headers.
The easiest way to fix your problem is to put the Task class in a proper header file, as it should be anyway.

SGaist

Hi,

To add to @Chris-Kawa, the other technic here would be to add

#include "main.moc"

At the bottom of your main.cpp file.

ODБOï

Thank you very much