"Multitudes of Objects: First Implementation and Case Study for Java"
Friedrich Steimann
Jesper Öqvist
Görel Hedin
erschienen in:
The Journal of Object Technology, Volume 13, no. 5 (September 2014), Pages 1:1-33

In object-oriented programs, the relationship of an object to many objects is usually implemented using indirection through a collection.This is in contrast to a relationship to one object, which is usually implemented directly. However, using collections for relationships to many objects does not only mean that accessing the related objects always requires accessing the collection first, it also presents a lurking maintenance problem that manifests itself when a relationship needs to be changed from to-one to to-many or vice versa. Continuing our prior work on fixing this problem, we show how we have extended the Java 7 programming language with multiplicities, that is, with expressions that evaluate to a number of objects not wrapped in a container, and report on the experience we have gathered using these multiplicities in a case study.

ein Vieles, welches kein Eines ist
(a multitude which is not a one)
— inspired by Georg Cantor’s conception of a set as “jedes Viele, welches sich als Eines denken läßt”, i.e., any multitude which can be thought of as a one

Friedrich Steimann | 12.08.2021