How to show private inheritance relationship in a UML class diagram

Question

In C++ since private inheritance is not considered as an is-a relationship, how is it supposed to be shown in a class diagram and if it is shown as a has-a

Answer 1

It should be a Composition relationship (solid black diamond on the subclass side), because:

• Private inheritance means "implemented in terms of" but in this regard it can be simply treated the same as "has a" relationship.
• An instance of the subclass clearly owns the base calss part of the object, and the ownership is not shared with any other objects.