Q_OBJECT error

[Toshikazu]

Hey, my code compiles fine but I cannot connect my own functions to a signal. Is the reason because i have not put the Q_OBJECT macro in the class header file for the window?

if so when i do put this macro in i get 2 errors.

make: *** [debug] Error 2
make[1]: *** [debug\buttonTest.exe] Error 1

I was hoping if i fixed this then i would be able to connect signals to my own functions.

-----------------

class Window : public QWidget
{
	Q_OBJECT
 
public:
	Window(QWidget *parent = 0)
	{
		button = new QPushButton("Increment", this);
		lcd = new QLCDNumber(2, this);
		slider = new QSlider(Qt::Horizontal);
		slider->setRange(0,99);
		slider->setValue(0);
 
		QObject::connect(slider, SIGNAL(valueChanged(int)), 
				         this, SLOT(Update(int)));
				         //lcd, SLOT(display(int)));
 
		QVBoxLayout *layout = new QVBoxLayout;
		layout->addWidget(slider);
		layout->addWidget(lcd);
		layout->addWidget(button);
		this->setLayout(layout);
 
	}
 
private slots:
	void Update(int i)
	{
		lcd->display(i);
	}
 
 
private:
	QPushButton *button;
	QLCDNumber *lcd;
	QSlider *slider;
};

class Window : public QWidget
{
	Q_OBJECT
	
public:
	Window(QWidget *parent = 0)
	{
		button = new QPushButton("Increment", this);
		lcd = new QLCDNumber(2, this);
		slider = new QSlider(Qt::Horizontal);
		slider->setRange(0,99);
		slider->setValue(0);
		
		QObject::connect(slider, SIGNAL(valueChanged(int)), 
				         this, SLOT(Update(int)));
				         //lcd, SLOT(display(int)));
		
		QVBoxLayout *layout = new QVBoxLayout;
		layout->addWidget(slider);
		layout->addWidget(lcd);
		layout->addWidget(button);
		this->setLayout(layout);
		
	}
	
private slots:
	void Update(int i)
	{
		lcd->display(i);
	}

	
private:
	QPushButton *button;
	QLCDNumber *lcd;
	QSlider *slider;
};

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//.pro file
TEMPLATE = app
TARGET = buttonTest
QT += core \
    gui
HEADERS += buttontest.h
SOURCES += main.cpp \
    buttontest.cpp
FORMS += buttontest.ui
RESOURCES +=

//.pro file
TEMPLATE = app
TARGET = buttonTest
QT += core \
    gui
HEADERS += buttontest.h
SOURCES += main.cpp \
    buttontest.cpp
FORMS += buttontest.ui
RESOURCES +=

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[lyuts]

Q_OBJECT macro should be in your class definition and your function should be declared in "slots" section. In this case you'll be able to do "your connect".

[Toshikazu]

Ok thanks.

But when i try to include the Q_OBJECT macro i get those errors ?

[mazurekwrc]

do you place Q_OBJECT in private section of your class ?
and remeber that your class should inherit someway from QObject class

[ChristianEhrlicher]

There must be an earlier problem - the lines you post don't tell us anything. Also you did not tell us how you create the makefile. If you're using qmake then also show us your pro-File.

[vycke]

Did you also make sure that your class derives from QObject (either directly or indirectly)?
Vycke

[Toshikazu]

I have edited my original post to show the code for my class and for my .pro file. Although i am not that clear yet on the purpose of the .pro file.

[ChristianEhrlicher]

Did you rerun qmake after you added Q_OBJECT to your header?
And what's the actual error - as I said the error message you gave us isn't the first one you see and we can't say anything about the real problem.
The pro-file looks fine.

OT: But why did you put the implementation into the header? This isn't a good coding style.

[Toshikazu]

Hi, thnanks for your time.

I put the implementation in the header, becauase when I do not i get an additional error message. Even if it is all in the same file.

undefined reference to `vtable for Window'

Also I am new to eclipse and qt, This might sound dumb but am I not rerunning qmake when i save the source and build all and run? or do i need to do something else.

Thanks

[ChristianEhrlicher]

You have to rerun qmake every time you add/remove Q_OBJECT in an header - otherwise qmake can't create the moc calls for the headers and you get a vtable linker error.

[Toshikazu]

How do I rerun qmake and what files do i need to pass.
Or does qmake get invoked by eclipse everytime I do a build project?

I tried this on cmd but I still get the errors.

qmake -makefile -win32 C:/Eclipse/buttonTest/buttonTest.pro
qmake -project -win32 C:/Eclipse/buttonTest/buttonTest.pro

and they both didn't output any errors when i run them. But still errors when i try to build the project.

Sorry my understanding is low.