copy constructor of an inherited class

Question

I'm trying to define the copy constructor of a class but I'm mistaking. I'm trying to do a son of QGraphicsRectItem using this constructor:

QGraphicsRectItem( qreal x, qreal y, qreal width, qreal height, QGraphicsItem * parent = 0 )

here some code

QGraphicsRectItem defined by QtL

QGraphicsRectItem( qreal x, qreal y, qreal width, qreal height, QGraphicsItem * parent = 0 )

Cell.h, son's class:

Cell();
Cell(const Cell &c);
Cell(qreal x, qreal y, qreal width, qreal height, QGraphicsItem * parent = 0 );

Cell.cpp:

Cell::Cell() {}

/* got error defining this constructor (copy constructor) */
Cell::Cell(const Cell &c) :
    x(c.rect().x()), y(c.rect().y()),
    width(c.rect().width()), height(c.rect().height()), parent(c.parent) {}


Cell::Cell(qreal x, qreal y, qreal width, qreal height, QGraphicsItem *parent) : 
    QGraphicsRectItem(x, y, width, height, parent) {
    ...
    // some code
    ...
}

error says:

/../../../../cell.cpp:7: error: class 'Cell' does not have any field named 'x'
/../../../../cell.cpp:7: error: class 'Cell' does not have any field named 'y'
/../../../../cell.cpp:7: error: class 'Cell' does not have any field named 'width'
/../../../../cell.cpp:7: error: class 'Cell' does not have any field named 'height'
/../../../../cell.cpp:7: error: class 'Cell' does not have any field named 'parent'

thank you

Answer 1

You need to make your copy constructor as follows:

Cell::Cell(const Cell &c)
    :
        QGraphicsRectItem(c.rect().x(), c.rect().y(),
                          c.rect().width(), c.rect().height(),
                          c.parent())
{}

The reason is that your Cell class is a QGraphicsRectItem because of inheritance. Thus c argument of the constructor is also representing QGraphicsRectItem , so you can use its QGraphicsRectItem::rect() and QGraphicsRectItem::parent() functions to construct new object - the copy of c .