The single Inheritance Approach

[raphaelf]

Hi everybody
I have created a widget with the designer. Now i am trying to subclass it like the doc, i get following error by compiling. Can somebody see the problem?
main.cpp

#include <QApplication>
#include "dialog.h"
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    Dialog dialog;
    dialog.show();
    return app.exec(); 
}

#include <QApplication>
#include "dialog.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
   
    Dialog dialog;
    dialog.show();
    return app.exec(); 
}

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dialog.h

#include "ui_widget1.h"
 
 
class Dialog : public QDialog
{
    Q_OBJECT
 
    public:
    	Dialog(QWidget *parent = 0);
 
    private:
    	Ui::Dialog ui;
};

#include "ui_widget1.h"


class Dialog : public QDialog
{
    Q_OBJECT
    
    public:
    	Dialog(QWidget *parent = 0);
    
    private:
    	Ui::Dialog ui;
};

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dialog.cpp

#include "dialog.h"
 
Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
{
	ui.setupUi(this);
 
}

#include "dialog.h"

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
{
	ui.setupUi(this);

}

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ui_widget1.h

#ifndef UI_WIDGET1_H
#define UI_WIDGET1_H
 
#include <QtCore/QVariant>
#include <QtGui/QAction>
#include <QtGui/QApplication>
#include <QtGui/QButtonGroup>
#include <QtGui/QPushButton>
#include <QtGui/QWidget>
 
class Ui_Widget1
{
public:
    QPushButton *btn1;
    QPushButton *btn1_2;
 
    void setupUi(QWidget *Widget1)
    {
    Widget1->setObjectName(QString::fromUtf8("Widget1"));
    Widget1->resize(QSize(181, 101).expandedTo(Widget1->minimumSizeHint()));
    btn1 = new QPushButton(Widget1);
    btn1->setObjectName(QString::fromUtf8("btn1"));
    btn1->setGeometry(QRect(50, 40, 75, 24));
    btn1_2 = new QPushButton(Widget1);
    btn1_2->setObjectName(QString::fromUtf8("btn1_2"));
    btn1_2->setGeometry(QRect(100, 70, 75, 24));
    retranslateUi(Widget1);
 
    QMetaObject::connectSlotsByName(Widget1);
    } // setupUi
 
    void retranslateUi(QWidget *Widget1)
    {
    Widget1->setWindowTitle(QApplication::translate("Widget1", "Ich bin ein Widget", 0, QApplication::UnicodeUTF8));
    btn1->setText(QApplication::translate("Widget1", "Show Message", 0, QApplication::UnicodeUTF8));
    btn1_2->setText(QApplication::translate("Widget1", "Show Message", 0, QApplication::UnicodeUTF8));
    Q_UNUSED(Widget1);
    } // retranslateUi
 
};
 
namespace Ui {
    class Widget1: public Ui_Widget1 {};
} // namespace Ui
 
#endif // UI_WIDGET1_H

#ifndef UI_WIDGET1_H
#define UI_WIDGET1_H

#include <QtCore/QVariant>
#include <QtGui/QAction>
#include <QtGui/QApplication>
#include <QtGui/QButtonGroup>
#include <QtGui/QPushButton>
#include <QtGui/QWidget>

class Ui_Widget1
{
public:
    QPushButton *btn1;
    QPushButton *btn1_2;

    void setupUi(QWidget *Widget1)
    {
    Widget1->setObjectName(QString::fromUtf8("Widget1"));
    Widget1->resize(QSize(181, 101).expandedTo(Widget1->minimumSizeHint()));
    btn1 = new QPushButton(Widget1);
    btn1->setObjectName(QString::fromUtf8("btn1"));
    btn1->setGeometry(QRect(50, 40, 75, 24));
    btn1_2 = new QPushButton(Widget1);
    btn1_2->setObjectName(QString::fromUtf8("btn1_2"));
    btn1_2->setGeometry(QRect(100, 70, 75, 24));
    retranslateUi(Widget1);

    QMetaObject::connectSlotsByName(Widget1);
    } // setupUi

    void retranslateUi(QWidget *Widget1)
    {
    Widget1->setWindowTitle(QApplication::translate("Widget1", "Ich bin ein Widget", 0, QApplication::UnicodeUTF8));
    btn1->setText(QApplication::translate("Widget1", "Show Message", 0, QApplication::UnicodeUTF8));
    btn1_2->setText(QApplication::translate("Widget1", "Show Message", 0, QApplication::UnicodeUTF8));
    Q_UNUSED(Widget1);
    } // retranslateUi

};

namespace Ui {
    class Widget1: public Ui_Widget1 {};
} // namespace Ui

#endif // UI_WIDGET1_H

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ERROR:

dialog.h:5: error: invalid use of undefined type `struct QDialog'
D:/apps/Qt/4.1.3/include/QtGui/../../src/gui/kernel/qwindowdefs.h:38: error: for
ward declaration of `struct QDialog'
dialog.h:12: error: using-declaration for non-member at class scope
dialog.h:12: error: expected `;' before "ui"
In file included from dialog.cpp:1:
dialog.h:13:3: warning: no newline at end of file
dialog.cpp: In constructor `Dialog::Dialog(QWidget*)':
dialog.cpp:4: error: type `struct QDialog' is not a direct base of `Dialog'
dialog.cpp:6: error: `ui' undeclared (first use this function)
dialog.cpp:6: error: (Each undeclared identifier is reported only once for each
function it appears in.)
dialog.cpp:8:2: warning: no newline at end of file
mingw32-make[1]: *** [release\dialog.o] Error 1
mingw32-make[1]: Leaving directory `W:/Data/qt4/einstieg/widget'
mingw32-make: *** [release] Error 2

dialog.h:5: error: invalid use of undefined type `struct QDialog'
D:/apps/Qt/4.1.3/include/QtGui/../../src/gui/kernel/qwindowdefs.h:38: error: for
ward declaration of `struct QDialog'
dialog.h:12: error: using-declaration for non-member at class scope
dialog.h:12: error: expected `;' before "ui"
In file included from dialog.cpp:1:
dialog.h:13:3: warning: no newline at end of file
dialog.cpp: In constructor `Dialog::Dialog(QWidget*)':
dialog.cpp:4: error: type `struct QDialog' is not a direct base of `Dialog'
dialog.cpp:6: error: `ui' undeclared (first use this function)
dialog.cpp:6: error: (Each undeclared identifier is reported only once for each
function it appears in.)
dialog.cpp:8:2: warning: no newline at end of file
mingw32-make[1]: *** [release\dialog.o] Error 1
mingw32-make[1]: Leaving directory `W:/Data/qt4/einstieg/widget'
mingw32-make: *** [release] Error 2

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Thank you

[jpn]

You designed a widget in the designer, but are using the Ui for a dialog. It works this way, because QDialog inherits QWidget, but more appropriate way is to design a dialog for a dialog, a widget for a widget and a mainwindow for a mainwindow.

// dialog.h
#include "ui_widget1.h"
// you must include this because you designed a widget in the designer
#include <QDialog>
 
class Dialog : public QDialog
{
	Q_OBJECT
 
public:
	Dialog(QWidget *parent = 0);
 
private:
	Ui::Widget1 ui; // corrected the name, check the object name property in the designer
};

// dialog.h
#include "ui_widget1.h"
// you must include this because you designed a widget in the designer
#include <QDialog>

class Dialog : public QDialog
{
	Q_OBJECT

public:
	Dialog(QWidget *parent = 0);

private:
	Ui::Widget1 ui; // corrected the name, check the object name property in the designer
};

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[raphaelf]

Hi JPN!!
Thanks it works. I will design a dialog for a dialog..