Communication between MainWindow and a dialog

[marcel]

Since you create the dialog with the main window as parent, you could do a cast to get an instance of the window type:

((MainWindowClass*)parent())->resetKey(K2);

((MainWindowClass*)parent())->resetKey(K2);

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Regards

[Backslash]

I'm sorry, but I don't quite understand what doing a cast means.

The MainWindow instance is called mainWin (from main.cpp)

QApplication app(argc, argv);
    MainWindow mainWin;
    mainWin.show();
    return app.exec();

QApplication app(argc, argv);
    MainWindow mainWin;
    mainWin.show();
    return app.exec();

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So do you mean for me to write:

((MainWindow*)parent())->resetKey(K2);

or something else entirely?

Thanks,
Backslash

[marcel]

Yes, the easiest way is to do that.
In on_buttonBox_accepted, replace the last line with:

((MainWindow*)parent())->resetKey(K2);

((MainWindow*)parent())->resetKey(K2);

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Should work.

To find out what a cast is, do a search on google on"c++ inheritance and polymorphism".

Regards

[Backslash]

Thanks again for the help,

When I use that line "((MainWindow*)parent())->resetKey(K2);" I get this error message from make:

keydialog.cpp: In member function `void KeyDialog:n_buttonBox_accepted()':
keydialog.cpp:117: error: `MainWindow' undeclared (first use this function)
keydialog.cpp:117: error: (Each undeclared identifier is reported only once for
each function it appears in.)
keydialog.cpp:117: error: expected primary-expression before ')' token
keydialog.cpp:117: error: expected `)' before "parent"
mingw32-make[1]: *** [release\keydialog.o] Error 1

Did I misunderstand something?

[marcel]

You have to include MainWindow.h in keydialog.cpp.

A more elegant solution is to create a getter in the keydialog. This will return the key (K2).
So, in the slot on_push_0_clicked, you can do:

if(dialog.exec() == QDialog::Accepted )
{
 Key::Key k = dialog.getKey2();
 resetKey(k);
}

if(dialog.exec() == QDialog::Accepted )
{
 Key::Key k = dialog.getKey2();
 resetKey(k);
}

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Regards

[Backslash]

Wow, that is a neat solution. Definitely going to try that one...

Thanks for the patience and the insight,
Backslash

[Backslash]

Is this the order in which I should put this?

void MainWindow::on_push_0_clicked()
    {
    KeyDialog dialog(this);
    dialog.setKey(zero);
    dialog.exec();
        if(dialog.exec() == QDialog::Accepted )
        {
        Key::Key k = dialog.getKey();
        resetKey(k);
        }
    }

void MainWindow::on_push_0_clicked()
    {
    KeyDialog dialog(this);
    dialog.setKey(zero);
    dialog.exec();
        if(dialog.exec() == QDialog::Accepted )
        {
        Key::Key k = dialog.getKey();
        resetKey(k);
        }
    }

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In KeyDialog, My getKey(); looks like this:

Key getKey()
 {
 return K2;
 }

Key getKey()
 {
 return K2;
 }

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(K2 is defined at the top of KeyDialog because I use on_buttonBox_accepted to take the current state of the form's widgets and translate those into values to be stored in K2)

All of this seems ok to me but I'm getting a wierd error from make:

release\mainwindow.o(.text+0x8455):mainwindow.cpp: undefined reference to `KeyDi
alog::getKey()'
release\mainwindow.o(.text+0x9915):mainwindow.cpp: undefined reference to `KeyDi
alog::getKey()'
release\mainwindow.o(.text+0xadd5):mainwindow.cpp: undefined reference to `KeyDi
alog::getKey()'
release\mainwindow.o(.text+0xc295):mainwindow.cpp: undefined reference to `KeyDi
alog::getKey()'
release\mainwindow.o(.text+0xd755):mainwindow.cpp: undefined reference to `KeyDi
alog::getKey()'
release\mainwindow.o(.text+0xec15):mainwindow.cpp: more undefined references to
`KeyDialog::getKey()' follow
collect2: ld returned 1 exit status

I have no clue what that's about...

Thanks again,
Backslash

[marcel]

Well, this looks like c++ mistake:
When you implement a function in a class, you have to prepend the name of the class and the resolution operator to it:

Key::Key KeyDialog::getKey()
{
  return K2;
}

Key::Key KeyDialog::getKey()
{
  return K2;
}

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Now, K2 has to be a member of the class in order to be visible in any of the class's member functions.

Also, the correct thing to do is:

void MainWindow::on_push_0_clicked()
      {
          KeyDialog dialog(this);
          dialog.setKey(zero);
          if(dialog.exec() == QDialog::Accepted )
          {
              Key::Key k = dialog.getKey();
              resetKey(k);
          }
      }

void MainWindow::on_push_0_clicked()
      {
          KeyDialog dialog(this);
          dialog.setKey(zero);
          if(dialog.exec() == QDialog::Accepted )
          {
              Key::Key k = dialog.getKey();
              resetKey(k);
          }
      }

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exec(), by default, returns an exit code which shows you whether the user pressed ok or cancel( accepted or rejected).
So you need to call exec only once.

The compile errors tell you that you did not declared/defined the getKey function.
To declare a function - means you add it in the class declaration, in the header:

class KeyDialog : ...
{
 public:
    Key::Key getKey();
};

class KeyDialog : ...
{
 public:
    Key::Key getKey();
};

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The function definition means the implementation. It appears that you have donh that( incorrectly although ).

So, fix these errors and try again.

Regards

[Backslash]

Thanks for all the help. I'm glad there's a newbie section of this forum.
Now I just have to work out some more kinks in my code and implement a few more functions.

Thanks again,
Backslash