Clone refactoring inspection by summarizing clone refactorings and detecting inconsistent changes during software evolution

摘要

It has been broadly assumed that removing code clones by refactorings would solve theproblems of code duplication. Despite recent empirical studies on the benefit ofrefactorings, contradicting evidence shows that it is often difficult or impossible toremove clones by using standard refactoring techniques. Developers cannot easilydetermine which clones can be refactored or how they should be maintained scatteredthroughout a large code base in evolving systems. We propose pattern-based clonerefactoring inspection (PRI), a technique for managing clone refactorings. PRI summarizesrefactorings of clones and detects clones that are not consistently refactored.To help developers refactor these anomalies, PRI also visualizes clone evolution andrefactorings and fixes refactoring anomalies to prevent the clone group from being leftin an inconsistent state. We evaluated PRI on 6 open-source projects and showed thatit identifies clone refactorings with 94.1% accuracy and detects inconsistentrefactorings with 98.4% accuracy, tracking clone change histories. In a study with 10student developers, the participants reported that flexible PRI's summarization anddetection features can be valuable for novice developers to learn about refactoringsto clones. These results show that PRI should improve developer productivity ininspecting clone refactorings distributed across multiple files in evolving systems.