Using machine states correctly

El3ctroGh0st

Hello,

I'm trying to implement to states in my program. Those are the relevant code snippets (it isn't the whole code, I've deleted some of the functions as to make it shorter):

//Header file
#ifndef JAPANESEMEMORISER_HPP
#define JAPANESEMEMORISER_HPP

#include <QMainWindow>
#include <QStateMachine>

#include "configurationbox.hpp"
#include "sessionbox.hpp"

namespace Ui {
class JapaneseMemoriser;
}

class JapaneseMemoriser : public QMainWindow
{
    Q_OBJECT
private:
    Ui::JapaneseMemoriser *ui;

    QState *configurationState = nullptr;
    QState *sessionState = nullptr;

    void configureStates();
    void enterSessionMode();
    void enterConfigurationMode();
};

#endif // JAPANESEMEMORISER_HPP

//Source file
#include "japanesememoriser.hpp"
#include "ui_japanesememoriser.h"

#include <QDesktopWidget>
#include <QDebug>

JapaneseMemoriser::JapaneseMemoriser(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::JapaneseMemoriser),
    configBox(new ConfigurationBox(this)),
    sessionBox(new SessionBox(this))
{
    ui->setupUi(this);

    configureStates();

    connect(configurationState, &QState::entered, this, &JapaneseMemoriser::enterConfigurationMode);
    connect(sessionState, &QState::entered, this, &JapaneseMemoriser::enterSessionMode);
}

void JapaneseMemoriser::configureStates()
{
    QStateMachine qmachine;
    configurationState = new QState();
    sessionState = new QState();

    configurationState->addTransition(ui->sessionButton, &QPushButton::pressed, sessionState);
    sessionState->addTransition(ui->sessionButton, &QPushButton::pressed, configurationState);

    qmachine.addState(configurationState);
    qmachine.addState(sessionState);
    qmachine.setInitialState(configurationState);
    qmachine.start();
}

void JapaneseMemoriser::enterConfigurationMode()
{
    ui->sessionButton->setText("Start Session");
    sessionBox->setVisible(false);
    configBox->setVisible(true);
}

void JapaneseMemoriser::enterSessionMode()
{
    ui->sessionButton->setText("End Session");
    sessionBox->setVisible(true);
    configBox->setVisible(false);
}

I've used this site as a guide line for the configuration. However, for some reason it doesn't seem to work. The program does start, but none of the implemented functionalities seem to work. Once I close the program, I get an "unexpected crash" error message. I have the feeling that it might be because the QStateMachine works asynchronously (although I'm not sure). If so, how should I change the program?

mranger90

Could it be because the qmachine is local and will be destroyed when configureStates() exits ?

El3ctroGh0st

Ha, yep this was the problem. Thanks a lot!