how to get the pointer to parent widget/object?

[squidge]

The parent is already given to your constructor, so just store it somewhere?

Alternatively, you can use parentWidget()

[rambo83]

It does not work, if I use "parentWidget()->updateChromosome()". The error says:
plot.cpp:453: error: 'class QWidget' has no member named 'updateChromosome'

my mainFrame looks like this:

mainframe.h:

#include "plot.h"
#include <qwt_plot_picker.h>
 
using namespace std;
 
class mainFrame : public QMainWindow
{
    Q_OBJECT
 
public:
    mainFrame(QWidget *parent = 0);
 
...

#include "plot.h"
#include <qwt_plot_picker.h>

using namespace std;

class mainFrame : public QMainWindow
{
    Q_OBJECT

public:
    mainFrame(QWidget *parent = 0);

...

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mainframe.cpp:

mainFrame::mainFrame(QWidget *parent)
    : QMainWindow(parent)
{
	ui.setupUi(this);
...
d_plot = new Plot(this);
	layout_plot->addWidget(d_plot);

mainFrame::mainFrame(QWidget *parent)
    : QMainWindow(parent)
{
	ui.setupUi(this);
...
d_plot = new Plot(this);
	layout_plot->addWidget(d_plot);

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So how to get the pointer to the mainFrame class?

My idea was to include mainframe.h into plot.h and declare there

mainFrame *_mf;

mainFrame *_mf;

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and then store the passed pointer to it, but I have already includede plot.h into mainframe.h, so there will be conflict!

Help me please.

[Lykurg]

You just have to cast the pointer to your class.

[rambo83]

In this case it is not possible, because I have already included the definition of class "Plot" into the header file of class "mainFrame", so that I cannot include the definition of class "mainFrame" into the header or cpp file of class "Plot"

If I however do so (#inlcude "mainframe.h" in plot.cpp) and then:

mainFrame *mf = dynamic_cast<mainFrame*>(parentWidget());
			mf->updateChromosome( selected_Points[i]->value(),index);

mainFrame *mf = dynamic_cast<mainFrame*>(parentWidget());
			mf->updateChromosome( selected_Points[i]->value(),index);

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then I get this error:
plot.h:11: error: redefinition of 'class Plot'
plot.h:12: error: previous definition of 'class Plot'

So I must somehow trick it around, but how?

[Lykurg]

then I get this error:
plot.h:11: error: redefinition of 'class Plot'
plot.h:12: error: previous definition of 'class Plot'

So I must somehow trick it around, but how?

Then is your header file wrong! use something like:

#ifndef PLOT_H
#define PLOT_H
 
class Plot : ...
 
#endif

#ifndef PLOT_H
#define PLOT_H

class Plot : ...

#endif

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[Lykurg]

In this case it is not possible, because I have already included the definition of class "Plot" into the header file of class "mainFrame", so that I cannot include the definition of class "mainFrame" into the header or cpp file of class "Plot"

You can use a forward declaration!

class mainFrame;
 
class Plot
{
  public:
    Plot(mainFrame *mf = 0);
//...
};

class mainFrame;

class Plot
{
  public:
    Plot(mainFrame *mf = 0);
//...
};

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[rambo83]

Yes, you are right, Lykurg!

I have just found something about forward declaration in Google and used it in my code and it works now! Thank you very much.

best regards,

Vitali