<![CDATA[Slot and Signal problem custom class]]>Hello,

I have a problem, i create one class for the differente action and i would like put the different slot on this class. But, when i create the connexion, it use the slot on the class for my ui and not in my class.

I explaine : My ui is in the class "MainWindowTracage." and the slot, i put on the class "MainWindowsAction." but, if i create the signal with this line : connect(window->ui->pushButton, SIGNAL(clicked()),action, SLOT(test()) ); on the class MainWindows Action it don't work.
I have this error message :

QObject::connect: No such slot QMainWindow::test() in ..\ihm_tracage\src\mainwindowsaction.cpp:8
QObject::connect:  (sender name:   'pushButton')

Do you have any solution for fixe my problem ?

the code :
mainwindowsaction.cpp :

#include "header\mainwindowsaction.h"

MainWindowsAction::MainWindowsAction(MainWindowTracage *window, MainWindowsAffichageMe *affichage, MainWindowsAction *action)
{
    this->window = window;
    this->affichage = affichage;

    connect(window->ui->pushButton, SIGNAL(clicked()),action, SLOT(MainWindowsAction::test()) );

}

void MainWindowsAction::test()
{
    printf("ok");
}

mainwindowsaction.h :

#ifndef MAINWINDOWSACTION_H
#define MAINWINDOWSACTION_H

#include "mainwindowsaffichageMe.h"
#include "mainwindowtracage.h"

#include "ui_mainwindowtracage.h"

class MainWindowsAction : public QMainWindow
{
    public:
        MainWindowsAction(MainWindowTracage *window, MainWindowsAffichageMe *affichage, MainWindowsAction *action);
    public slots:
        void test();
    private:
        MainWindowTracage *window;
        MainWindowsAffichageMe *affichage;
;
};

thank's for your answer !

]]>https://forum.qt.io/topic/131801/slot-and-signal-problem-custom-classRSS for NodeSun, 27 Sep 2026 20:23:30 GMTMon, 08 Nov 2021 10:53:37 GMT60<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 13:06:14 GMT]]>@vin212 said in Slot and Signal problem custom class:

I change for :

    connect(window->ui->pushButton, &QPushButton::clicked,this, &MainWindowsAction::test );

and i add Q_OBJECT
but i have an other error message :

Yes, it's maybe this problem, i recompile and it's work
Thank's for your answers

After adding Q_OBJECT to a class, you need rerun moc (Meta-Object Compiler).
Take a look at following links for more details!

]]>https://forum.qt.io/post/689082https://forum.qt.io/post/689082Mon, 08 Nov 2021 13:06:14 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 12:47:19 GMT]]>@vin212 said in Slot and Signal problem custom class:

and i add Q_OBJECT

Regardless of any other issues. Any time you add Q_OBJECT to an already defined and compiled class you must do a complete rebuild. This is a known practicality. If you do not, you are liable to get precisely the vtable error you got for that class.

]]>https://forum.qt.io/post/689068https://forum.qt.io/post/689068Mon, 08 Nov 2021 12:47:19 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 11:38:41 GMT]]>@J-Hilk

Yes, it's maybe this problem, i recompile and it's work

Thank's for your answers

]]>https://forum.qt.io/post/689047https://forum.qt.io/post/689047Mon, 08 Nov 2021 11:38:41 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 11:27:48 GMT]]>@vin212
seems like the compiler was unable to properly construct the polymorphism relations

My bet would be because your only constructor
MainWindowsAction(MainWindowTracage *window, MainWindowsAffichageMe *affichage, MainWindowsAction *action);

requieres a pointer to an other instance of your class.

]]>https://forum.qt.io/post/689042https://forum.qt.io/post/689042Mon, 08 Nov 2021 11:27:48 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 11:26:56 GMT]]>Ok !

I change for :

connect(window->ui->pushButton, &QPushButton::clicked,this, &MainWindowsAction::test );

and i add Q_OBJECT
but i have an other error message :

mainwindowsaction.cpp:3: erreur : undefined reference to `vtable for MainWindowsAction'
debug/mainwindowsaction.o: In function `ZN17MainWindowsActionC2EP17MainWindowTracageP22MainWindowsAffichageMePS_':
mainwindowsaction.cpp:3: undefined reference to `vtable for MainWindowsAction'

I add the destructor and is the same.

]]>https://forum.qt.io/post/689040https://forum.qt.io/post/689040Mon, 08 Nov 2021 11:26:56 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 11:07:42 GMT]]>@vin212 you're missing Q_OBJECTmacro in your header, old qt4 connect syntax does not work without it.
also action is wrong here as receiver object, it ought to be this

all in all its this quite wrong:

connect(window->ui->pushButton, SIGNAL(clicked()),action, SLOT(MainWindowsAction::test()) );

thats mixing syntaxes

connect(window->ui->pushButton, SIGNAL(clicked()),this, SLOT(test()) );

or preferably

connect(window->ui->pushButton, &QPushButton::clicked, this ,&MainWindowsAction::test );
]]>https://forum.qt.io/post/689037https://forum.qt.io/post/689037Mon, 08 Nov 2021 11:07:42 GMT<![CDATA[Reply to Slot and Signal problem custom class on Mon, 08 Nov 2021 11:01:02 GMT]]>@vin212
Start by changing over to New Signal Slot Syntax instead of using your SIGNAL/SLOT() macros, the compile-time errors you will receive while you get your code right will be much more helpful.

From the error message you show you cannot have action, SLOT(MainWindowsAction::test()) in your connect(). And/or you reference a QMainWindow::test() on the line it tells you, and there is no such slot.

]]>https://forum.qt.io/post/689035https://forum.qt.io/post/689035Mon, 08 Nov 2021 11:01:02 GMT