Signal between 2 class

Yacinoben

Hello,
I have 2 classes and I have to connect them with a signal

A::A()
{
QListView *view=new QListView(this)
/*
..
*/
connect(view,&QListView::clicked,this,[ ](){emit newSignal();});
};
B::B()
{
A *a=new A;
connect(a,&A::newSignal,this,()[ ]{qDebug("test");});
}

sorry for not post a complet code, he's long.
Signal of QListView is works, but newSignal is not emited !
Thanks for your help :)

Chris Kawa

Please post the actual code. This won't even compile.
[ ](){emit newSignal();} this lambda does not capture this so it would be a compilation error to try and call newSignal() from it.
()[ ]{qDebug("test");} the parenthesis are all backwards.
How and where is newSignal declared? Do you have a Q_OBJECT macro in you A class declaration?

praveen0991kr

connect(this->view,&QListView::clicked, this,[=]{
emit this->newSignal();
});

micland

@Yacinoben
Why using lambda in the first connect statement? You can directly connect signals with signals:

connect(view, &QListView::clicked, this, &A::newSignal);

Yacinoben

It doesn't work .
this is my code :

class History : public QDialog
{
    Q_OBJECT
public:
    explicit History(QWidget *parent = 0);

signals:
    void selectHistory();
};

History::History(QWidget *parent) : QDialog(parent)
{
/*
...
*/
     connect(view,&QListView::clicked,this,&History::selectHistory);
}

void MainWindow::showHistory()
{
    History *history=new History(this);
    history->exec();
    connect(history,&History::selectHistory,this,[ ] () {qDebug("test);});
}

The QListView contains a history of browser, i would like when i click in a index, i open a new tab in my navigator with a fonction addTab in Mainwindow, but the signal doesn't work

miho

http://easy-qt.blogspot.ru/2012/10/1.html

p.s. russian site

SGaist

Hi,

You're doing your connection after exec which means that it will happen after you close your history dialog thus you won't see any message.

On a side note, you are leaking memory since you don't delete history. The objects will get destroyed when MainWindow is since you give it a parent but the memory will fill up more each time you call showHistory.

Yacinoben

Yes, you are right, when i call history, the object doesn't deletes, the use of the memory increases.
but now, its work !!

   History *history=new History(this);
   history->setAttribute(Qt::WA_DeleteOnClose);
   connect(history,&History::selectHistory,this,[ ] () {qDebug("test");});
   history->exec();

Thank's

Chris Kawa

It's easier and shorter to just create it on the stack:

History history(this);
connect(&history,&History::selectHistory, this, [ ]{ qDebug("test"); } );
history.exec();

Yacinoben

Thanks !