Assignment operator, copy constructor, destructor

Canvas::~Canvas( )
{
    delete [] objects;
}

void Canvas::operator =( const Canvas& canvas )
{
    if (this == &canvas) // self-assignment 'A=A', nothing to do
        return;

    delete [] objects;
    
    objects = new MovingObject [canvas.capacity];
    capacity = canvas.capacity;
    n = canvas.n;

    copy (canvas.objects, canvas.objects + canvas.capacity, objects);
}

Canvas::Canvas( const Canvas& canvas )
{
    capacity = 8;
    objects = new MovingObject [capacity];
    n = 0;

    // instead of the three above lines a single line
    //     objects = NULL;
    // would also work

    *this = canvas;
}