Modular Reasoning in the Presence of Event Subtyping

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Separating crosscutting concerns while preserving modular reasoning is challenging. Type-based interfaces (event types) separate modularized crosscutting concerns (observers) and traditional object-oriented concerns (subjects). Event types paired with event specifications were shown to be effective in enabling modular reasoning about subjects and observers. Similar to class subtyping, organizing event types into subtyping hierarchies is beneficial. However, unrelated behaviors of observers and their arbitrary execution orders could cause unique, somewhat counterintuitive, reasoning challenges in the presence of event subtyping. These challenges threaten both tractability of reasoning and reuse of event types. This work makes three contributions. First, we pose and explain these challenges. Second, we propose an event-based calculus to show how these challenges can be overcome. Finally, we present modular reasoning rules of our technique and show its applicability to other event-based techniques.

Bib Info

  author = {Bagherzadeh, Mehdi and Dyer, Robert and Fernando, Rex D. and S\'{a}nchez, Jos{\'e} and Rajan, Hridesh},
  title = {Modular Reasoning in the Presence of Event Subtyping},
  booktitle = {Proceedings of the 14th International Conference on Modularity},
  series = {MODULARITY 2015},
  year = {2015},
  isbn = {978-1-4503-3249-1},
  location = {Fort Collins, CO, USA},
  pages = {117--132},
  numpages = {16},
  url = {},
  doi = {10.1145/2724525.2724569},
  acmid = {2724569},
  publisher = {ACM},
  address = {New York, NY, USA},
  keywords = {Event subtyping, event specification refinement, event type inheritance, modular rea- soning, translucid contracts},