Hoiw do I resolve axxess to "protected " object ?

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I am trying to identify the "sender" of Qt "connect" function.

the

int i = RXobject->senderSignalIndex();

seems a good way to accomplish my task, but...

I get the "protected" member and do not know how to proceed...

Please ignore irrelevant code , this is "under construction"
and I am asking C++ question , nothing to do with Qt.

C++

void   MainWindow_Bluetooth::processMenu(int index_submenu, int index_mainmenu)
{
#ifdef LAMBDA
    text = "TASK DEBUG connect... "; //connect
    text += Q_FUNC_INFO;
    text += QString::number(__LINE__);
    // move index to class !!!
    text += " main loop index_main ";
    text += QString::number(index_mainmenu);
    text += " embeded loop  index_sub ";
    text += QString::number(index_submenu);
    text += " main loop class passed index ";
    text += QString::number(index);
    qDebug() << text;
#endif
    {// analyze indexes received block
        QString text;
        QObject *RXobject = sender();
        RXobject->dumpObjectInfo();
        QObjectList children = RXobject->children();
       //; text = RXobject->children().at(0);
        //QObjectList *RXChildren = RXobject->children();
        //QObject *RXparent = RXobject->parent();
        //QObject *TEST_parent = RXparent->parent();

        // protected member ???
int i = RXobject->senderSignalIndex();


//int SenderIndex = RXobject::senderSignalIndex();

        //text = RXobject->dumpObjectInfo();

        text = Q_FUNC_INFO;
        qDebug() << text;

/mnt/A_BT_DEC10/BT__PROGRAMS/A_JAN11/A_BT_LIBRARY/terminal_Bluetooth/mainwindow_Bluetooth_copy.cpp:3890: error: 'senderSignalIndex' is a protected member of 'QObject'
mainwindow_Bluetooth_copy.cpp:3890:19: error: 'senderSignalIndex' is a protected member of 'QObject'
int i = RXobject->senderSignalIndex();
                  ^
/home/nov25-1/Qt/5.15.2/gcc_64/include/QtCore/qobject.h:435:9: note: can only access this member on an object of type 'MainWindow_Bluetooth'
    int senderSignalIndex() const;
        ^

What I have tried:

Ask Mrs Google to provide example of "sender(*) " usage... no luck

Posted 24-Jan-24 6:59am

Salvatore Terress

Updated 24-Jan-24 7:08am

PIEBALDconsult

v2

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3 solutions

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Dave Kreskowiak · Answer 1 · 2024-01-24T08:47:00

Solution 1

If I understand what you're trying to do, you don't "resolve" that method. Protected members of a class are only accessible from the class code itself or from inheritors of the class, which I think is QObject.

Since your code is neither, you cannot call that method. It's for internal use of the QObject class itself. That's why you can't find any information on it on the web.

Posted 24-Jan-24 8:47am

Dave Kreskowiak

Comments

Salvatore Terress 24-Jan-24 15:02pm

I found this
QMetaMethod metaMethod = sender()->metaObject()->method(senderSignalIndex());
I really do not know HOW it works, but it manages to access senderSignalIndex , but the index returned does not make sense... so part of the problem is solved.. I will RTFM about QMetaMethod next...

KarstenK 25-Jan-24 4:41am

he should get the source code from https://www.qt.io/download-open-source

KarstenK · Answer 2 · 2024-01-24T22:41:00

Solution 2

Because QT is open source you can get the source code.
Read the documentation for details. Normally some installation and preparation. Pay attention that you need some compatible OS.

Posted 24-Jan-24 22:41pm

KarstenK

CPallini · Answer 3 · 2024-01-25T00:23:00

Solution 3

I guess you should replace

Quote:
int i = RXobject->senderSignalIndex();

with

int i = senderSignalIndex();

Posted 25-Jan-24 0:23am

CPallini