Advanced Features

Abstract

In this chapter, we elaborate on the ideas of properties, attributes and semi-associations, all of them introduced in earlier chapters and collectively called features. We introduce some additional characteristics of features, such as the idea that features which must preserve the order of their instances may be marked as sorted in a model. We also explain that semi-associations that connect a class to another that is mentioned on its definition should be marked as strong, to capture the fact that a definitional dependency exists between the classes. Then, we deal with the awkward but common phenomenon that some self-associations involve a single role and therefore a single semi-association; we explain that these are called symmetric self-associations and present a special notation for them. Finally, we explain that associations with overall semantics of “contains”, “shares” or “refers to” can be depicted through a compact notation, which results in tidier diagrams.