Methodbook: Recommending Move Method Refactorings via Relational Topic Models

Abstract

Abstract-During software maintenance and evolution the internal structure of the software system undergoes continuous changes. These modifications drift the source code away from its original design, thus deteriorating its quality, including cohesion and coupling of classes. Several refactoring methods have been proposed to overcome this problem. In this paper we propose a novel technique to identify Move Method refactoring opportunities and remove the Feature Envy bad smell from source code. Our approach, coined as Methodbook, is based on Relational Topic Models (RTM), a probabilistic technique for representing and modeling topics, documents (in our case methods) and known relationships among these. Methodbook uses RTM to analyze both structural and textual information gleaned from software to better support move method refactoring. We evaluated Methodbook in two case studies. The first study has been executed on six software systems to analyze if the move method operations suggested by Methodbook help to improve the design quality of the systems as captured by quality metrics. The second study has been conducted with eighty developers that evaluated the refactoring recommendations produced by Methodbook. The achieved results indicate that Methodbook provides accurate and meaningful recommendations for move method refactoring operations.

The Scent of a Smell: An Extensive Comparison Between Textual and Structural Smells

“…Therefore, we had to select more than one technique to carry out our investigation. Given our definition of structural code smells, we discarded all the approaches that use a combination of more sources of information (e.g., the techniques by Bavota et al [8], [11], [12]), as well as the approaches using other types of information (e.g., the change history information [74]). Furthermore, we avoided the use of industrial tools such as inCode [43] and iPlasma [44], and code quality checkers (e.g., PMD 1 or Checkstyle 2 ) for two main reasons.…”

“…In general, tools detecting the Feature Envy code smell [8], [88], [100] are also Move Method refactoring tools, although algorithms used to recommend refactoring solutions are more lightweight than the decomposition algorithms used by Extract Method and Extract Class refactoring tools. We selected JDeodorant [100] as there are no other structural-based tools able to detect this emphMove Method smell with a comparable accuracy [28].…”

“…The research community spent a lot of effort studying the extent to which code smells tend to remain in a software project for long periods of time [4], [22], [61], [84], as well as their negative impact on non-functional properties of source code, such as program comprehension [1], change-and fault-proneness [48], [49], testability [77], [68] and, more generally, maintainability [97], [111], [109]. As a consequence, several tools and techniques have been proposed to help developers in detecting code smells and to suggest refactoring opportunities [12], [8], [65], [67], [74], [75], [100].…”

Analysis of Metric-Based Object-Oriented Code Refactoring Opportunities Identification Approaches

“…However, during software evolution or maintenance, as the software systems' internal structure is subjected to continuous enhancement, modification and adaptation, its code becomes comp lex and consequently drift away fro m the orig inal design [5] [21]. Furthermo re, poor design decisions due to strict condition of deadline forces developers not to adhered to the princip le of h igh cohesion and low coupling [11] [12].…”

“…To assess the performance of MethodBook, Oliveto et al [ 11] performed a preliminary emp irical evaluation on software system known as ArgoUM L version 0. 16 [21] proposed a novel method to specifically detect bad smell in code feature envy and automatically fix them with move method refactoring. Their approach is also called the Methodbook and is based on the approach of R3 -RTM discussed in [11] and [12].…”