Section: New Results

Dynamic Languages: Language Constructs for Modular Design

Magic Literals in Pharo Literals are constant values (numbers, strings, etc.) used in the source code. Magic literals are the ones used without a clear explanation of their meaning. Presence of such literals harms source code readability, decreases its modularity, and encourages code duplication. Identifying magic literals is not straightforward. A literal can be considered self-explanatory in one context and magic in another. We need a heuristic to help developers spot magic literals. We study and characterize the literals in Pharo. We implemented a heuristic to detect magic literals and integrated it as a code critic rule for System Browser and Critics Browser in Pharo 7. We run our heuristic on 112,500 Pharo methods which reported 23,292 magic literals spread across 8,986 methods. We manually validated our approach on a random subset of 100 methods and found that 62% of the reported literals in those methods are indeed magic. [3]

Towards easy program migration using language virtualization Migrating programs between language versions is a daunting task. A developer writes a program in a particular version of a language and cannot foresee future language changes. In this article, we explore a solution to gradual program migration based on virtualization at the programming language level. Our language virtualization approach adds a backwards-compatibility layer on top of a recent language version, allowing developers to load and run old programs on the more recent infrastructure. Developers are then able to migrate the program to the new language version or are able to run it as it is. Our virtualization technique is based on a dynamic module implementation and code intercession techniques. Migrated and non-migrated parts co-exist in the meantime allowing an incremental migration procedure. We validate it by migrating legacy Pharo programs, MuTalk and Fuel. [10]