On the Composition of Design Patterns

Design patterns are usually applied in a composed form with each other. It is crucial to be able to formally reason about how patterns can be composed and to prove the properties of composed patterns. Based on our previous work on formal specification of design patterns and formal reasoning about their properties, this paper focuses on the composition of design patterns. A notion of composition of patterns with respect to overlaps is formally defined based on two operations on design patterns, which are the specialisation of a pattern with constraints and the lifting of a pattern with a subset of components as the key. The composition of design patterns is illustrated by the composition of Composite, Strategy and Observer patterns. A case study of the formalisation of the relationship between patterns as suggested by GoF is also reported

Formal specification of the variants and behavioural features of design patterns

The formal specification of design patterns is widely recognized as being vital to their effective and correct use in software development. It can clarify the concepts underlying patterns, eliminate ambiguity and thereby lay a solid foundation for tool support. This paper further advances a formal meta-modelling approach that uses first order predicate logic to specify design patterns. In particular, it specifies both structural and behavioural features of design patterns and systematically captures the variants in a well-structured format. The paper reports a case study involving the formal specification of all 23 patterns in the Gang of Four catalog. It demonstrates that the approach improves the accuracy of pattern specifications by covering variations and clarifying the ambiguous parts of informal descriptions

On the Composability of Design Patterns

In real applications, design patterns are almost always to be found composed with each other. It is crucial that these compositions be validated. This paper examines the notion of validity, and develops a formal method for proving or disproving it, in a context where composition is performed with formally defined operators on formally specified patterns. In particular, for validity, we require that pattern compositions preserve the features, semantics and soundness of the composed patterns. The application of the theory is demonstrated by a formal analysis of overlap-based pattern compositions and a case study of a real pattern-oriented software design

An Algebra of Design Patterns

In a pattern-oriented software design process, design decisions are made by selecting and instanti- ating appropriate patterns, and composing them together. In our previous work, we enabled these decisions to be formalised by dening a set of operators on patterns with which instantiations and compositions can be represented. In this paper, we investigate the algebraic properties of these operators. We provide and prove a complete set of algebraic laws so that equivalence between pattern expressions can be proven. Furthermore, we dene an always-terminating normalisation of pattern expressions to a canonical form, which is unique modulo equivalence in rst-order logic. By a case study, the pattern-oriented design of an extensible request-handling framework, we demonstrate two practical applications of the algebraic framework. Firstly, we can prove the correctness of a nished design with respect to the design decisions made and the formal specication of the patterns. Secondly, we can even derive the design from these components

Wenn Kostüme sprechen – Musterforschung in den Digital Humanities am Beispiel vestimentärer Kommunikation im Film

Um sich dem komplexen diegetischen Gestaltungselement des Filmkostüms zu nähern, wird im Rahmen der vorliegenden Arbeit aufgezeigt, wie mit Hilfe eines interdisziplinären Methodensets bestehende Fragestellungen – hier im Besonderen: Gibt es eine sogenannte ‚Kostümsprache‘ und wenn ja, wie kann die Konkretisierung einer solchen aussehen? – aus neuen Blickwinkeln heraus, Betrachtung erfahren können. Indem hierzu im Speziellen unterschiedliche Konzepte aus der Informatik in die Medienwissenschaft überführt werden, um einen modernen Ansatz für die Analyse der vestimentären Kommunikation im Film zu ermöglichen, ist das Vorgehen methodisch im Kontext der Digital Humanities zu verorten. Um dem als problematisch geltenden Begriff der ‚Kostümsprache’ neu zu begegnen, wird mit dem MUSE-Ansatz erstens ein neuer methodischer Ansatz zur Identifikation einer konkreten Kostümsprache mittels des Musterkonzeptes vorgestellt, und zweitens praktisch gezeigt, wie dieser Ansatz durch die MUSE-Werkzeugumgebung, bestehend aus dem MUSE-Repository und den MUSE-Analyse-Werkzeugen, unterstützt werden kann. Hiermit soll die Möglichkeit aufgezeigt werden, das ‚Wissen‘, das über die filmisch-vestimentäre Kommunikation in Filmen vorhanden ist, extrahierbar, analysierbar und zu Kostümmustern abstrahierbar zu machen. Die Kostümmuster, als Wissensbausteine untereinander zu einer Mustersprache verbunden, bieten abstrakt erfasstes, konventionalisiertes Lösungswissen zu Designproblemen, wie man mittels des Kostüms bestimmte Charaktere, deren Eigenschaften und Transformationen, kommunizieren kann