Creating a Dialog in a Slot of QMainWindow

[tilm]

Thanks for your answers but the mistakes you pointed out do not seem to be the crucial ones. I still get the same compiler error. And obviously the compiler stops even before it recognizes the second specification of a default argument in the Dialog constructor because I did not get an error for this.

The second mistake would 'only' cause a memory leak and no compiler error, right?

[spirit]

your code

#include "Dialog.h"
 
Dialog::Dialog(QWidget *parent = 0) : QWidget(parent){
    Ui::Dialog *ui = new Ui::Dialog;
    ui.setupUi(this);
}

#include "Dialog.h"
 
Dialog::Dialog(QWidget *parent = 0) : QWidget(parent){
    Ui::Dialog *ui = new Ui::Dialog;
    ui.setupUi(this);
}

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must be

#include "Dialog.h"
 
Dialog::Dialog(QWidget *parent) : QWidget(parent){
    Ui::Dialog *ui = new Ui::Dialog;
    ui.setupUi(this);
}

#include "Dialog.h"
 
Dialog::Dialog(QWidget *parent) : QWidget(parent){
    Ui::Dialog *ui = new Ui::Dialog;
    ui.setupUi(this);
}

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yup, memory leak.

[tilm]

Yes, I corrected the mistakes in the way you suggested. But I still get the same compiler error I mentioned above in my first post:

release\MainWindow.o(.text+0x28f):MainWindow.cpp: undefined reference to 'Dialog::Dialog(QWidget*)'

The problem must be somewhere else and I suspect that I am not aware of a property of QMainWindow that prevents me to create an instance of a Dialog inside its member functions. Remember: the same code works in member functions of classes that inherit other QObjects.

I reduced the MainWindow class even further and still get the same error:

class MainWindow : public QMainWindow {
 
public:	
	MainWindow(QWidget *parent=0,Qt::WFlags flags=0);
	void createDialog();
 
private:
	Ui::MainWindow *ui;
};
 
MainWindow::MainWindow(QWidget *parent,Qt::WFlags flags){
	ui = new Ui::MainWindow;
	ui->setupUi(this);
	createDialog();
}
 
void MainWindow::createDialog(){
	Dialog d;
}

class MainWindow : public QMainWindow {
	
public:	
	MainWindow(QWidget *parent=0,Qt::WFlags flags=0);
	void createDialog();
	
private:
	Ui::MainWindow *ui;
};

MainWindow::MainWindow(QWidget *parent,Qt::WFlags flags){
	ui = new Ui::MainWindow;
	ui->setupUi(this);
	createDialog();
}

void MainWindow::createDialog(){
	Dialog d;
}

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[spirit]

can you attach compilable sources?

[jpn]

Do you have dialog.cpp in the .pro file? If not, that would explain why you didn't get compilation errors but managed to pass to the linking stage.

[tilm]

Thanks jpn, this was the problem. I always thought that

qmake -project

was sufficient to create a complete .pro file (I'm sure that I ran it before qmake and make). For me this was the first time that something in a .pro file created with qmake was missing. Do you know the reason for this?

[tilm]

I think I found the answer on my own: 'qmake -project' only includes dialog.cpp into the .pro file when dialog.h is included in MainWindow.h . But I first included the Dialog header file in MainWindow.cpp. That was the reason.