Clause 39: Use private inheritance wisely and prudently (using private inheritance judiciously)

Note:

1.private inheritance means is-implemented-in-terms-of (implemented according to something). It is usually lower than the compound (composition) level. But when derivated class needs to access the protected base class

Member, or need to redefine the inherited virtual function, it is reasonable to design this.

2. Unlike composite (composition), private inheritance can result in the optimization of empty base. This may be important for developers who are committed to minimizing the size of objects.

Clause 39: Use private inheritance wisely and prudently (using private inheritance judiciously)