Question

I have the following classes:

class cManipulator : public cEditor
{
 public:
    cManipulator( ICanvas *canvas, cCompositeRoot* obj );
    ~cManipulator();
 private:
    ....
    class VisitorSetProp* m_SetVisitor;
    class VisitorGetProp* m_GetVisitor;
}

cManipulator::cManipulator( ICanvas* canvas, cCompositeRoot* obj ) :
...
{
...
    m_SetVisitor = new VisitorSetProp (this);
    m_GetVisitor = new VisitorGetProp (this);
}

cManipulator::~cManipulator()
{
    delete m_SetVisitor;
    delete m_GetVisitor;
}

class VisitorSetProp : public Visitor
{
public:
......
}

class VisitorGetProp : public Visitor
{
public:
....
}

What the variant on UML class diagram is right?

or

Answer 1

The first one is right (named composition), since the cManipulator has the lifetime responsibility for m_SetVisitor and m_GetVisitor.

The second one is named aggregation. It’s used when more then one object point to the visitors, and they are not resposible for the lifetime.

Regards