Лямбда-выражения в QObject::connect

Form_1::Form_1(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Form_1)
{
    ui->setupUi(this);

    connect(ui->checkBox_1, &QCheckBox::stateChanged, this, &Form_1::showForm2);
}
...
void Form_1::showForm2(int state)
{
    if(state == Qt::Checked) {
        form2 = new Form_2(this); // Form2 *form2; declared in form1.h
        form2->show();
        connect(form2, &Form_2::finished, [this](){
            ui->checkbox_1->setCheckState(Qt::Unchecked);
        });
    }
    else if (state == Qt::Unchecked){
        delete form2;
    }
}