How to design API headers

Library headers (API) should be minimal and not change very often. If this directive is followed, then the API is more direct, and any internal changes do not reflect to recompiling the whole user project.

The following article describes what steps to take to achieve this goal on an C++ API header.

Forward declarations vs includes in headers

What should be included and what can be forward declared in this header ?

class Polygon : public Shape {

public:
    void setBasicCurve (const Bezier& curve);
    void magnify (Vector direction);
    void setPoints (const vector<Point*>& points);

private:
    Plane*             m_surface;
    std::list<Point*>  m_points;
    Color              m_color;
    Bezier&            m_basic_curve;

    static Type        m_shape_type;

};

Here are some practical tips to keep your header files lean.