How to open MainWindow with signal

[isan]

I want to open MainWindow with button clicked signal, but the MainWindow close right after open it, why this happening?

 Dialog dialog;
 dialog.show();
 QObject::connect(
     &dialog, &Dialog::onSetClicked,
     [](const QString &port, const QString &config, const QString &model) {
       MainWindow demo(port, config, model);
       demo.show();
     });

[mpergand]

@isan said in How to open MainWindow with signal:

QObject::connect(
&dialog, &Dialog::onSetClicked,
[](const QString &port, const QString &config, const QString &model) {
MainWindow demo(port, config, model); --> local variable !
demo.show();
});

[isan]

@mpergand can you explain more?

[SGaist]

Hi,

You create demo in your lambda. It will be destroyed at the end of the function.

[isan]

@SGaist How can I fix it?

[mpergand]

@isan How can I fix it?

MainWindow* demo=new MainWindow(port, config, model);

Don't forget to add this in the MainWindow constructor:

setAttribute(Qt::WA_DeleteOnClose);

otherwise you will have a memory leak.

[mrjj]

@mpergand
did we miss a new in the code ?

[mpergand]

@mrjj said in How to open MainWindow with signal:

@mpergand
did we miss a new in the code ?

Yes indeed :)