added clarifying note for C.139

This commit is contained in:
Bjarne Stroustrup 2017-04-30 13:33:35 -04:00
parent b3584cfa5f
commit e0de4df83b

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@ -7091,6 +7091,12 @@ Consistent use of `override` would catch this.
##### Note
Note every class is meant to be a base class.
Most standard-library classes are examples of that (e.g., `std::vector` and `std::string` are not designed to be derived from).
This rule are about using `final` on classes with virtual functions meant to be interfaces for a class hierarchy.
##### Note
Claims of performance improvements from `final` should be substantiated.
Too often, such claims are based on conjecture or experience with other languages.