Combining Aspects and Modules

Modules and aspects are different approaches to a common goal of constructing large, complex software quickly. Unfortunately, neither is solely sufficient. We demonstrate that the differences between modules and aspects are not irreconcilable, and that a carefully crafted module system can cater to aspect-oriented features. We show that it is possible to combine the software-engineering features of module systems with aspects’ abilities to modularize crosscutting behaviors. We present an existence proof in the form of a prototype module system, Aspectual Collaborations, combining separate compilation, modular reasoning, type safe reuse, and aspectual interception of behavior from oblivious base modules. Type soundness is shown to hold for a minimal model of the system. By tempering the power of aspects with encapsulation boundaries maintained by a module system, the desirable qualities of both are achieved while tempering their respective weaknesses.