Error: no matching function for call to 'QObject::connect

[Paul Colby]

The problem is with the winContent lifetime.

void MainWindow::buildPage()
{
    MainWindowContent winContent;

    ui->centralWidget->setLayout(winContent.getPageWidgetsLayout());
    // at this point, winContent is destroyed, and automatically disconnected.
}

You probably want to do something more like:

void MainWindow::buildPage()
{
    MainWindowContent * winContent = new MainWindowContent(this);

    ui->centralWidget->setLayout(winContent->getPageWidgetsLayout());
}

Or move the slot to the MainWindow class.

Cheers.

[WhatIf]

Thank you very much for all the help!

The last problem I have is how to pass the label and lineedit to the slot. I don't want to make them global variables. if I create a custom signal with the label and lineedit to match the slot, I'm confused about where to emit the signal.

[SGaist]

Before that, why do you need the MainWindowContent. It looks like a convoluted mean to create the central widget content.

[WhatIf]

I want to keep the logic of how the program progresses from page to page in MainWindow. But I want other classes to generate the pages to be displayed. Basically I want to be able to manage the program without having a single .cpp file that is a thousand lines or so.

[SGaist]

Then why not make them full QWidget derivative ?

That's what is usually done, cut your application in logical pieces and then build as many QWidget based classes as needed to keep the code clean, simple and tidy.

[WhatIf]

Can you give an example please? Or direct me to any tutorial on the topic?

[SGaist]

The scribble example is a simple example to start with.

[WhatIf]

I went over the example but I still have some difficulty converting it to my use. I created a MainWindowContent that is a subclass of QWidget and created a

QGridLayout* MainWindowContent::getPageWidgetsLayout()

the exact same function I provided in the code above.

I don't think that this is the intended goal of this example because in MainWindow an instance of the QWidget subclass (ScribbleArea) is passed to setCentralWidget not a call to a function using the instance. Am I supposed to move all the code from getPageWidgetsLayout() to the constructor and declare the label, lineedit, and pushbutton as private variables.

[SGaist]

No the example shows what I suggested: create a separated widget that encapsulates the functionality of interest and use that one in the MainWindow.

[WhatIf]

Finally, I got it to work but I still have the same problem that I started with. How do I pass the line edit and label to the slot?

I searched online and all the examples have a condition other than the button being clicked that emit the signal . Any hints please?

[VRonin]

https://forum.qt.io/topic/86414/error-no-matching-function-for-call-to-qobject-connect/5