Java Extensions for Design Pattern Instantiation

Design patterns are not easily traceable in source code, leading to maintainability and comprehension issues, while the instantiation of certain patterns involves generalizable boiler-plate code. We provide high-level language constructs addressing design patterns that transform source code by injecting a substantial part of their implementation at compile time. We developed proof of concept extensions addressing widely used design patterns, namely Singleton, Visitor, Decorator, and Observer, using annotations as the means to extend Java. We describe our Java annotations to support these design patterns and the associated source code transformations, demonstrating that it is possible to significantly reduce the necessary code to instantiate a pattern through the use of high-level constructs.