Qt插槽和信号：MainWindow中没有匹配功能

Question

I have looked at a variety of the Qt discussions for this error "no matching function for call to" and I still cannot see what is different in this case. I have successfully set up slot/signal pairs between GUI elements, but for some reason the latest set of slot/signal pairs is creating an error.

In order to allow all GUI elements to update the status bar on the main window I have created a signal in each panel as shown here

class PanelA : public QWidget
{
  ...
  public signals:
     void UpdateStatusBar(std::string);
  ...
}

Then in MainWindow there is a slot

//from MainWindow.h
class MainWindow : public QMainWindow
{
  private slots:
     void ReceiveStatus(std::string);
}

//from MainWindow.cpp
void MainWindow::ReceiveStatus(std::string s)
{
  //I can provide other controls, filters, etc.
  //but currently there are none
  ui->statusBar->showMessage(tr("System status: "+s));
}

And finally, in the MainWindow constructor I have several signals already and I have added one new connect line for each GUI element.

connect(ui->panelA, &PanelA::SelectionChanged, ui->panelB, &PanelB::UpdateSelection);
//this one works
connect(ui->panelA, &PanelA::UpdateStatusBar, ui, &MainWindow::ReceiveStatus);
//this one generates an error there is one status bar connection for each

So, as far as I can tell the syntax is right. both ui->panelA and ui are pointers. I don't know why one is correct and the other is wrong. I'd appreciate any suggestions.

Answer 1

Probably should be:

connect(ui->panelA, &PanelA::UpdateStatusBar, this, &MainWindow::ReceiveStatus);

The ui object isn't a MainWindow, but this will be.