Implementing Modular Class-based Reuse Mechanisms on Top of a Single Inheritance VM

Pablo Tesone (1, 2) , Guillermo Polito (3) , Luc Fabresse (1) , Noury Bouraqadi (1) , Stéphane Ducasse (2)

1 CERI SN - IMT Nord Europe - Centre for Digital Systems
2 RMOD - Analyses and Languages Constructs for Object-Oriented Application Evolution
3 CRIStAL - Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189

Code reuse is a good strategy to avoid code duplication and speed up software development. Existing object-oriented programming languages propose different ways of combining existing and new code such as e.g., single inheritance, multiple inheritance, Traits or Mixins. All these mechanisms present advantages and disadvantages and there are situations that require the use of one over the other. To avoid the complexity of implementing a virtual machine (VM), many of these mechanisms are often implemented on top of an existing high-performance VM, originally meant to run a single inheritance object-oriented language. These implementations require thus a mapping between the programming model they propose and the execution model provided by the VM. Moreover, reuse mechanisms are not usually composable, nor it is easy to implement new ones for a given language. In this paper, we propose a modular meta-level runtime architecture to implement and combine different code reuse mechanisms. This architecture supports dynamic combination of several mechanisms without affecting runtime performance in a single inheritance object-oriented VM. It includes moreover a reflective Meta-Object Protocol to query and modify classes using the programming logical model instead of the underlying low-level runtime model. Thanks to this architecture, we implemented Stateful Traits, Mixins, CLOS multiple inheritance, CLOS Standard Method Combinations and Beta prefixing in a modular and composable way.

Mots clés: code reuse; composable language features; performance

Domaines: Langage de programmation [cs.PL]

Pablo Tesone, Guillermo Polito, Luc Fabresse, Noury Bouraqadi, Stéphane Ducasse. Implementing Modular Class-based Reuse Mechanisms on Top of a Single Inheritance VM. SAC 2018:- The 33rd ACM/SIGAPP Symposium On Applied Computing, ACM/SIGAPP, Apr 2018, Pau, France. ⟨10.1145/3167132.3167244⟩. ⟨hal-01812612⟩