Exceptional C++: 47 Engineering Puzzles, Programming Problems, and Solutions

Chapter 24. Uses and Abuses of Inheritance

Difficulty: 6

“Why inherit?”

Inheritance is often overused, even by experienced developers. Always minimize coupling. If a class relationship can be expressed in more than one way, use the weakest relationship that's practical. Given that inheritance is nearly the strongest relationship you can express in C++ (second only to friendship), it's only really appropriate when there is no equivalent weaker alternative.

In this Item, the spotlight is on private inheritance, one real (if obscure) use for protected inheritance, and a recap of the proper use of public inheritance. Along the way, we will create a fairly complete list of all the usual and unusual reasons to use inheritance.

The following template provides ...