How to use Qt signals and slots in classes? - qt

Question

I created a QtGuiApplication with qt designer and add a simple class on it. In spite of this class inherits from QObject class and has Q_OBJECT macro in private section, the code doesn't run and I confronted with this error:
LNK2001 unresolved external symbol "public: virtual struct QMetaObject
const * __cdecl Sender::metaObject(void)const "
(?metaObject#Sender##UEBAPEBUQMetaObject##XZ) QtGuiApplication1
class header:
#ifndef SENDER_H
#define SENDER_H
#include <QObject>
class Sender : public QObject
{
Q_OBJECT
public:
explicit Sender(QObject *parent = 0);
void fireSignal();
signals:
void foo(const QString& arg);
};
#endif // SENDER_H
class cpp:
#include "Sender.h"
Sender::Sender(QObject *parent) :
QObject(parent)
{
}
void Sender::fireSignal()
{
emit foo("aa");
}
GUI header:
#pragma once
#include <QtWidgets/QMainWindow>
#include "ui_QtGuiApplication1.h"
class QtGuiApplication1 : public QMainWindow
{
Q_OBJECT
public:
QtGuiApplication1(QWidget *parent = Q_NULLPTR);
private:
Ui::QtGuiApplication1Class ui;
};
GUI cpp:
#include "QtGuiApplication1.h"
#include <QPainter>
QtGuiApplication1::QtGuiApplication1(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this);
}
When I comment Q_OBJECT macro and emit foo("aa"); it works.
Where do I make mistakes? Thanks.
edited: attach moc_Sender.cpp
/****************************************************************************
** Meta object code from reading C++ file 'Sender.h'
**
** Created by: The Qt Meta Object Compiler version 67 (Qt 5.11.1)
**
** WARNING! All changes made in this file will be lost!
*****************************************************************************/
#include "../../Sender.h"
#include <QtCore/qbytearray.h>
#include <QtCore/qmetatype.h>
#if !defined(Q_MOC_OUTPUT_REVISION)
#error "The header file 'Sender.h' doesn't include <QObject>."
#elif Q_MOC_OUTPUT_REVISION != 67
#error "This file was generated using the moc from 5.11.1. It"
#error "cannot be used with the include files from this version of Qt."
#error "(The moc has changed too much.)"
#endif
QT_BEGIN_MOC_NAMESPACE
QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
struct qt_meta_stringdata_Sender_t {
QByteArrayData data[4];
char stringdata0[16];
};
#define QT_MOC_LITERAL(idx, ofs, len) \
Q_STATIC_BYTE_ARRAY_DATA_HEADER_INITIALIZER_WITH_OFFSET(len, \
qptrdiff(offsetof(qt_meta_stringdata_Sender_t, stringdata0) + ofs \
- idx * sizeof(QByteArrayData)) \
)
static const qt_meta_stringdata_Sender_t qt_meta_stringdata_Sender = {
{
QT_MOC_LITERAL(0, 0, 6), // "Sender"
QT_MOC_LITERAL(1, 7, 3), // "foo"
QT_MOC_LITERAL(2, 11, 0), // ""
QT_MOC_LITERAL(3, 12, 3) // "arg"
},
"Sender\0foo\0\0arg"
};
#undef QT_MOC_LITERAL
static const uint qt_meta_data_Sender[] = {
// content:
7, // revision
0, // classname
0, 0, // classinfo
1, 14, // methods
0, 0, // properties
0, 0, // enums/sets
0, 0, // constructors
0, // flags
1, // signalCount
// signals: name, argc, parameters, tag, flags
1, 1, 19, 2, 0x06 /* Public */,
// signals: parameters
QMetaType::Void, QMetaType::QString, 3,
0 // eod
};
void Sender::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
{
if (_c == QMetaObject::InvokeMetaMethod) {
Sender *_t = static_cast<Sender *>(_o);
Q_UNUSED(_t)
switch (_id) {
case 0: _t->foo((*reinterpret_cast< const QString(*)>(_a[1]))); break;
default: ;
}
} else if (_c == QMetaObject::IndexOfMethod) {
int *result = reinterpret_cast<int *>(_a[0]);
{
using _t = void (Sender::*)(const QString & );
if (*reinterpret_cast<_t *>(_a[1]) == static_cast<_t>(&Sender::foo)) {
*result = 0;
return;
}
}
}
}
QT_INIT_METAOBJECT const QMetaObject Sender::staticMetaObject = {
{ &QObject::staticMetaObject, qt_meta_stringdata_Sender.data,
qt_meta_data_Sender, qt_static_metacall, nullptr, nullptr}
};
const QMetaObject *Sender::metaObject() const
{
return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject() : &staticMetaObject;
}
void *Sender::qt_metacast(const char *_clname)
{
if (!_clname) return nullptr;
if (!strcmp(_clname, qt_meta_stringdata_Sender.stringdata0))
return static_cast<void*>(this);
return QObject::qt_metacast(_clname);
}
int Sender::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
_id = QObject::qt_metacall(_c, _id, _a);
if (_id < 0)
return _id;
if (_c == QMetaObject::InvokeMetaMethod) {
if (_id < 1)
qt_static_metacall(this, _c, _id, _a);
_id -= 1;
} else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
if (_id < 1)
*reinterpret_cast<int*>(_a[0]) = -1;
_id -= 1;
}
return _id;
}
// SIGNAL 0
void Sender::foo(const QString & _t1)
{
void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(&_t1)) };
QMetaObject::activate(this, &staticMetaObject, 0, _a);
}
QT_WARNING_POP
QT_END_MOC_NAMESPACE