C++ Coding Standards: 101 Rules, Guidelines, and Best Practices

35. Avoid inheriting from classes that were not designed to be base classes

Summary

Some people don’t want to have kids: Classes meant to be used standalone obey a different blueprint than base classes (see Item 32). Using a standalone class as a base is a serious design error and should be avoided. To add behavior, prefer to add nonmember functions instead of member functions (see Item 44). To add state, prefer composition instead of inheritance (see Item 34). Avoid inheriting from concrete base classes.

Discussion

Using inheritance when it is not needed betrays a misplaced faith in the power of object orientation. In C++, you need to do specific things when defining base classes (see also Items 32, 50, and 54), and very different and often ...