How can I access public variable parent Form

[spirit]

could you prepare compilable example and show it?

[aurelius]

I attach a folder with 3 files, the parent header from QtDesigner and the child.

[aurelius]

The parent class is Ui_Form and the child class is paintimagewidget. I changed the names of the files. The original for the parent was ui_manysift.h and for the child paintimagewidget

[spirit]

there are two ways to set up ui
1.

//h-file
#include "ui_manysift.h"
 
class PaintImageWidget : public QWidget, private Ui::Form
{
    Q_OBJECT
....
};
 
//cpp-file
PaintImageWidget::PaintImageWidget(QWidget *parent)
   : QWidget(parent)
{
      setupUi(this);
}

//h-file
#include "ui_manysift.h"

class PaintImageWidget : public QWidget, private Ui::Form
{
    Q_OBJECT
....
};

//cpp-file
PaintImageWidget::PaintImageWidget(QWidget *parent)
   : QWidget(parent)
{
      setupUi(this);
}

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2.

//h-file
#include "ui_manysift.h"
 
class PaintImageWidget : public QWidget
{
    Q_OBJECT
....
private:
     Ui::Form m_ui;
};
 
//cpp-file
PaintImageWidget::PaintImageWidget(QWidget *parent)
   : QWidget(parent)
{
      m_ui.setupUi(this);
}

//h-file
#include "ui_manysift.h"

class PaintImageWidget : public QWidget
{
    Q_OBJECT
....
private:
     Ui::Form m_ui;
};

//cpp-file
PaintImageWidget::PaintImageWidget(QWidget *parent)
   : QWidget(parent)
{
      m_ui.setupUi(this);
}

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PS. this is not compilable example, I can't do qmake && nmake.

[aurelius]

I had a mistake in forward declaration. I found it, so now it works . Thanx for the help anyway ...

[rexi]

there are two ways to set up ui

I always wondered, is there a preferred way to do it? What are the advantages or disadvantages of either approach?

[spirit]

if modify second approch you can get more perfomance on compilation stage, i.e. if ui-file has been modified then only needed cpp file will be rebuild. this approach is very usefull in big project with many ui-files.

//h-file
#include <QWidget>
 
namespace Ui {
	class MyWidget;
};
 
class MyWidget: public QWidget
{
	Q_OBJECT
 
public:
	MyWidget(QWidget *parent = 0);
	virtual ~MyWidget();
 
private:
	Ui::MyWidget *m_ui;
};
 
//cpp-file
#include "mywidget.h"
#include "ui_mywidget.h"
 
MyWidget::MyWidget(QWidget *parent)
	: QWidget(parent)
{
	m_ui = new Ui::MyWidget;
	m_ui->setupUi(this);
}
 
MyWidget::~MyWidget()
{
	delete m_ui;
	m_ui = 0;
}

//h-file
#include <QWidget>

namespace Ui {
	class MyWidget;
};

class MyWidget: public QWidget
{
	Q_OBJECT

public:
	MyWidget(QWidget *parent = 0);
	virtual ~MyWidget();

private:
	Ui::MyWidget *m_ui;
};

//cpp-file
#include "mywidget.h"
#include "ui_mywidget.h"

MyWidget::MyWidget(QWidget *parent)
	: QWidget(parent)
{
	m_ui = new Ui::MyWidget;
	m_ui->setupUi(this);
}

MyWidget::~MyWidget()
{
	delete m_ui;
	m_ui = 0;
}

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[rexi]

So, in general there is no real advantage in any of the two first approaches, except that it's probably easiser to modify the second one to the third that you posted?

The third approach looks very interesting, I guess it can save quite some compile time while developing an application.

[spirit]

Yes the third one is usefull when you have a lot of ui files

[rexi]

I see that I always wondered what the difference between the first two ones was, but it just seems to be a matter of taste Thanks for clarifying that, and for pointing out the third one. I have to keep that one in mind, it might come in handy some day