Connecting buttons to mainwindows slot

Question

I tried to do a bunch of research on how to solve this problem, and everything is slightly different than my situation, or didn't work to fix my problem. I will start off by explaining my main goal. I have a main window with 7 buttons on it(amongst other things), when you hit each button, it closes out the current window and opens up a new window. All the windows will have the same 7 buttons, so you can go between each window. With all windows having the exact same 7 buttons, I wanted to set up a function that each class can call to set up each button and connect to a slot() in my mainwindow.cpp(called setupSubsystemButtons in example below). The actual buttons are being placed there, but they only work when pressed from my mainwindow.cpp....when I press them from a different class nothing happens.

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtWidgets>
#include <QDialog>


namespace Ui {
class MainWindow;
}

class MainWindow : public QDialog
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    QWidget *window;
    void setupSubsystemButtons(QGridLayout *layout);
    ~MainWindow();

private:
Ui::MainWindow *ui;

QLineEdit *tempValueBox;
QLineEdit *humidityValueBox;
QLineEdit *c02ValueBox;
...
public slots:
void ECSgeneralScreen();
void homeScreen();

};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "ecsgeneralcommand.h"

#include <QtWidgets>
#include <QtCore>

MainWindow::MainWindow(QWidget *parent) : QDialog(parent)
{

    QGridLayout *layout = new QGridLayout;
...
setLayout(layout);

}

void MainWindow::ECSgeneralScreen()
{
    ECSgeneralCommand *ECSgeneral = new ECSgeneralCommand;
    this->close();
    ECSgeneral->show();
    //opens up the ECS screen
}

void MainWindow::homeScreen()
{
    MainWindow *home = new MainWindow;
    this->close();
    home->show();
    //opens up the home screen
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::setupSubsystemButtons(QGridLayout *layout)
{
    //Push Button Layout
    homeScreenButton = new QPushButton("Home");
    layout->addWidget(homeScreenButton, 3, 11);
    connect(homeScreenButton, SIGNAL(clicked()), this, SLOT(homeScreen()));


    ECSgeneralScreenButton = new QPushButton("General");
    layout->addWidget(ECSgeneralScreenButton,5,11);
    connect(ECSgeneralScreenButton, SIGNAL(clicked()), this, SLOT(ECSgeneralScreen()));

}

ecsgeneralcommand.h

#ifndef ECSGENERALCOMMAND_H
#define ECSGENERALCOMMAND_H

#include <QDialog>
#include <QMainWindow>
#include <QtWidgets>
#include <QObject>
#include "mainwindow.h"

class ECSgeneralCommand : public QDialog
{
    Q_OBJECT

public:
    explicit ECSgeneralCommand(MainWindow *parent = 0);

private:
    ...

public slots:

};

#endif // ECSGENERALCOMMAND_H

ecsgeneralcommand.cpp

#include "ecsgeneralcommand.h"
#include "mainwindow.h"

#include <QtWidgets>
#include <QtCore>

ECSgeneralCommand::ECSgeneralCommand(MainWindow *parent) :   QDialog(parent)
{
    QGridLayout *layout = new QGridLayout;
    QWidget::setFixedHeight(600);
    QWidget::setFixedWidth(550);

    ...

    MainWindow setupButtons;
    //Setup Subsystem Buttons
    setupButtons.setupSubsystemButtons(layout);


    setLayout(layout);
};

Answer 1

    MainWindow setupButtons;
    //Setup Subsystem Buttons
    setupButtons.setupSubsystemButtons(layout);

This will create the buttons and connect their signals to slots of setupButtons, which will get deleted as soon as it's out of scope (the end of the ECSgeneralCommand constructor). So your buttons will be left connected to nothing.

You need to connect the button signals to an object that will exist at the time the button is pressed, such as the ECSgeneralCommand itself. Then it could close itself and spawn the correct window.

Or, possibly a much better solution, if applicable for your application: Use a single main window, with a QStackedWidget that switches widgets when a button is pressed. That's what's typically done.