Иерархия классов

#include <iostream>
#include <iomanip>
 
class shape
{
public:
    using border_color_t = int; // use whatever you want here, OS-dependent
    shape() : m_enabled(false), m_border_color(sm_default_border_color) {}
    virtual ~shape() {}
    virtual void draw() = 0;
    virtual void wipe() = 0;
    void switch_on() { m_enabled = true; draw(); }
    void switch_off() { m_enabled = false; wipe(); }
    bool is_enabled() const { return m_enabled; }
    void set_border_color(border_color_t border_color) { m_border_color = border_color; }
private:
    bool m_enabled;
    border_color_t m_border_color;
    static const border_color_t sm_default_border_color = 255;
};
 
class filled_shape : public shape
{
public:
    using fill_color_t = int; // use whatever you want here, OS-dependent
    filled_shape() : shape(), m_fill_color(sm_default_fill_color) { }
    virtual void fill() = 0;
    void set_fill_color(fill_color_t fill_color) { m_fill_color = fill_color; }
private:
    fill_color_t m_fill_color;
    static const fill_color_t sm_default_fill_color = 0;
};
 
class circle : public shape
{
public:
    circle() : shape(), m_center_x(sm_default_center_x), m_center_y(sm_default_center_y), m_radius(sm_default_radius) { }
    circle(unsigned center_x, unsigned center_y, unsigned radius) :
        shape(), m_center_x(center_x), m_center_y(center_y), m_radius(radius)
    { }
    void draw() override { /* draw the circle here, OS-dependent */ }
    void wipe() override { /* draw the circle here, OS-dependent */ }
private:
    unsigned m_center_x;
    unsigned m_center_y;
    unsigned m_radius;
    static const unsigned sm_default_center_x = 0; /* select any reasonable default */
    static const unsigned sm_default_center_y = 0;
    static const unsigned sm_default_radius = 0;
};
 
class rectangle : public shape
{
public:
    rectangle() : shape(),
        m_topmost_x(m_default_topmost_x), m_leftmost_y(m_default_leftmost_y),
        m_rightmost_x(m_default_rightmost_x), m_bottommost_y(m_default_bottommost_y)
    { }
    rectangle(unsigned topmost_x, unsigned leftmost_y, unsigned rightmost_x, unsigned bottommost_y) : shape(),
        m_topmost_x(topmost_x), m_leftmost_y(leftmost_y),
        m_rightmost_x(rightmost_x), m_bottommost_y(bottommost_y)
    { }
    void draw() override { /* draw the circle here, OS-dependent */ }
    void wipe() override { /* draw the circle here, OS-dependent */ }
private:
    unsigned m_topmost_x;
    unsigned m_leftmost_y;
    unsigned m_rightmost_x;
    unsigned m_bottommost_y;
    static const unsigned m_default_topmost_x = 0; /* select any reasonable default */
    static const unsigned m_default_leftmost_y = 0;
    static const unsigned m_default_rightmost_x = 0;
    static const unsigned m_default_bottommost_y = 0;
};
 
int main()
{
    circle c(100, 100, 50);
    rectangle r(50, 50, 150, 150);
 
    c.draw();
    r.draw();
 
    return 0;
}