Slot called two times for one signal

[fzminwl]

I have created some custom signal in a class BrowserTab (inherit from QMainWindow) class which receive and emit another signal :

BrowserTab::BrowserTab(QWidget *parent, WebPageView *view
                       ,QWebEngineProfile *profile, QString url)
    : QMainWindow(parent)
    , m_Profile(profile)
    , m_webView(view)
{
   //some initialisations
  [...]
     connect(m_webView, &WebPageView::newWindowRequested,  
       [this](BrowserTab* tab){ emit newWindowTabRequired(tab);
     });
}

[...]

It's parent ViewTabWidget will receive this signal and call the associated slot.
My problem is that when the signal is emitted, the slot is called two time.
I didn't add another connection for this signal, this is the only one!

ViewTabWidget::ViewTabWidget(QWebEngineProfile *profile,
                            TabsBehavior::Tabs how, QWidget * parent)
    : QTabWidget(parent)
    , fznavName(tr("Fz Navigator"))
    , newTabTitle(tr("New Tab"))
    , m_profile(profile)
{
    if(how == ViewTabWidget::NewTab){
         BrowserTab *tab = createNewBrowserTab();
         setUpTabConnexions(tab);
         addTab(tab, newTabTitle);
     }
     [...]
}

void ViewTabWidget::setUpTabConnexions(BrowserTab* newTab)
{
  [...]
//The slot is called two time when signal is emitted
  connect(newTab, &BrowserTab::newWindowTabRequired,
          this, &ViewTabWidget::handleNewBrowserTab);
 }

//And here the code for the slot : 
void ViewTabWidget::handleNewBrowserTab(BrowserTab *tab){
    this->addNewTab(tab, ViewTabWidget::BrowserWindow);
}

I know that i can add the optional argument Qt::UniqueConnection in the connect() function to avoid the slot being called two time but i don't understand why the slot is called two times.

connect(newTab, &BrowserTab::newWindowTabRequired,
        this, ViewTabWidget::handleNewBrowserTab, Qt::UniqueConnection)

So i need to understand why the slot is called two times.

A little help would be very grateful and sorry for my poor English !!

[SGaist]

Hi,

Might be a silly question but are you sure that your method setting connection is only called once ?

[JonB]

@fzminwl
How many times does setUpTabConnexions() get called, and so do the connect(), for a given tab? Put in a qDebug()/breakpoint to find out.

[fzminwl]

@SGaist @JonB It is called whenever a new tab is created and ready to be added to the ViewTabWidget widget.

[Christian Ehrlicher]

@fzminwl said in Slot called two times for one signal:

I know that i can add the optional argument Qt::UniqueConnection in the connect() function to avoid the slot being called two time but i don't understand why the slot is called two times.

Did you actually try it? If it works it means you do the connect twice as @JonB and @SGaist already said.

[fzminwl]

Like said @SGaist, that's just a silly question.
@SGaist said in Slot called two times for one signal:

Might be a silly question but are you sure that your method setting connection is only called once ?

I didn't pay attention to the methods that are called in the addNewTab() method. Indeed, setUpTabConnexions() is called twice at some point.

After using qDebug() and breakpoints, and I was able to find the cause of this problem.
Sorry to have bothered you!