Conclusion
From Andrey
The main point of this article is to consider the nature of an object's behavior as consisting of two aspects: the general behavior, provided by its class, and the behavior specific to a particular context in which the object is used. Conceptually, overriding in owner class is the mechanism for separating the object's behavior specific to a particular context (role) from the behavior specific to its class. Thus, overriding in owner class introduces a different way to organize the code defining the behavior. Looking at the examples within this article, one can see that it can make it easier to accomplish a variety of tasks, such as: to enforce class invariants concerning a member, as is done in the example with lee_jeans; to create an object managing two-way input and output, as is done in the example with visual_cash; to solve the updates issue, as is done in the example with working_girl; to write a class for immediate reuse without implementing all the minor details, as in the example with circular_gauge; to simplify and "objectify" the interface of a class, as in the example with int_property. Overriding in owner class can affect the way you create the designs, particularly in how you set up objects of unrelated classes to work together; how the processing of an action is split from its cause; how reusable classes are written. I think that this approach will help minimize dependencies between classes; reduce their need for updates; avoid redundant subclassing and dynamic structures; provide fuller control over class members. The ease with which this mechanism fits into C++ and the fact that it does not, in my opinion, create inconsistencies in the language makes me think that it logically and usefully extends the language.
Acknowledgments
I am grateful to Vitaly Shmatikov for reviewing the draft of this paper and helping in its improvement.
References
[1] A. Potekhin “Implementation of Overriding in Owner Class.” [[1]]
[2] E. Gamma et al., “Design Patterns, Elements of Reusable Object-Oriented Software”
