class MediatorInterface : public QObject
{
    Q_OBJECT

public:

    MediatorInterface(QObject *parent = 0);
    virtual ~MediatorInterface();

    
    ComponentOneInterface *componentOne() const;
    ComponentTwoInterface *componentTwo() const;
    ComponentThreeInterface *componentThree() const;


    void setComponentOne(ComponentOneInterface *componentOne);
    void setComponentTwo(ComponentTwoInterface *componentTwo);
    
protected:
    void setComponentThree(ComponentThreeInterface *componentThree);

private:
    MediatorInterfacePrivate *d;

private:
    MediatorInterface(const MediatorInterface &other);
    void operator = (const MediatorInterface &other);
};

//конструктор
MediatorInterface::MediatorInterface(QObject *parent)
    : QObject(parent),
      d(new MediatorInterfacePrivate())
{
}

//деструктор
MediatorInterface::~MediatorInterface()
{
    delete d;
}

//возвращает интерфейс компонента
ComponentOneInterface *MediatorInterface::componentOne() const
{
    return d->m_componentOne;
}

//устанавливает компонент
void MediatorInterface::setComponentOne(ComponentOneInterface *componentOne)
{
    d->m_componentOne = componentOne;
}

class MediatorInterfacePrivate {

public:
    MediatorInterfacePrivate();
    ~MediatorInterfacePrivate();


    QPointer<ComponentOneInterface> m_componentOne;
    QPointer<ComponentTwoInterface> m_componentTwo;
    QPointer<ComponentThreeInterface> m_componentThree;
    
};

//конструктор
MediatorInterfacePrivate::MediatorInterfacePrivate() :
    m_componentOne(0),
    m_componentTwo(0),
    m_componentThree(0)
{
}

//деструктор
MediatorInterfacePrivate::~MediatorInterfacePrivate()
{
    delete m_componentOne;
    delete m_componentTwo;
    delete m_componentThree;
}

class Mediator : public MediatorInterface
{
    Q_OBJECT

public:
    Mediator(QObject *parent = 0);
    virtual ~Mediator();
};


Mediator::Mediator(QObject *parent)
    : MediatorInterface(parent)
{

    ComponentThree *componentThree = new ComponentThree(this);
    setComponentThree(componentThree);
    ............
    создание компонентов чья функция set находится в секции protected
}

class ComponentOne: public ComponentOneInterface
{
    Q_OBJECT

public:
    ComponentOne(MediatorInterface *core, QObject *parent = 0);
    virtual ~ComponentOne();

    .....
}

class ActionEditor: public QDesignerActionEditorInterface
{
    Q_OBJECT
public:
    explicit ActionEditor(QDesignerFormEditorInterface *core, QWidget *parent = 0, Qt::WindowFlags flags = 0);
    virtual ~ActionEditor();
....

class QDesignerActionEditorInterface: public QWidget
{
    Q_OBJECT
public:
    QDesignerActionEditorInterface(QWidget *parent, Qt::WindowFlags flags = 0);
    virtual ~QDesignerActionEditorInterface();

    virtual QDesignerFormEditorInterface *core() const;
...........
};

void ActionEditor::restoreSettings()
{
    QDesignerSettingsInterface *settings = m_core->settingsManager();
    m_actionView->setViewMode(settings->value(QLatin1String(actionEditorViewModeKey), 0).toInt());
    updateViewModeActions();
}
...
void ActionEditor::manageAction(QAction *action)
{
    .....
    core()->metaDataBase()->add(action);

   .......

    QDesignerPropertySheetExtension *sheet = qt_extension<QDesignerPropertySheetExtension*>(core()->extensionManager(), action);
    sheet->setChanged(sheet->indexOf(QLatin1String(objectNamePropertyC)), true);
    sheet->setChanged(sheet->indexOf(QLatin1String(textPropertyC)), true);
    refreshIconPropertyChanged(action, sheet);

   ...............
}