Deriving Extract Method Refactoring Suggestions for Long Methods

Automatizing Software Cognitive Complexity Reduction

“…The first one (columns 4-11) is devoted to SSCC related metrics: iniCC is the initial cognitive complexity of the original methods (always above the threshold), extrac is the number of Extract Method refactorings proposed by the best solution, reducCC is the reduction on the cognitive complexity of the original methods, minReduc is the minimum reduction for a single extraction, maxReduc is the maximum reduction for a single extraction, avgReduc is the mean (average) reduction considering all extractions of the best solution, totalReduc is the sum of the reductions of all extractions of the best solution, and finalCC is the SSCC of the original methods after applying the sequence of Extract Method refactorings determined by the best solution. The second block (columns [12][13][14][15] shows LOC metrics, the third block (columns [16][17][18][19] provides information about the parameters involved in the extracted methods, and, finally, the last block the execution time in milliseconds.…”

“…In 2016, Haas and Hummel addressed the problem of finding the most appropriate refactoring candidate for long methods written in Java. The approach determines valid refactoring candidates and ranks them using a scoring function that aims to improve readability and reduce code complexity [14]. Later that year, Wijendra and Hewagamage proposed a cognitive complexity metric which determines the amount of information inside the software through cognitive weights and the way of information scattering in terms of Lines of Code (LOC) [30].…”

“…Due to its many uses [12], Extract Method has been recognized as the "Swiss army knife of refactorings" [10], [13]. It has also been recently used to reduce the complexity of code [14], [15] as we do in this paper. The main differences with already existing approaches are the following: they performed a more limited experimental validation, they do not impose any threshold for the cognitive complexity of the methods, and, most important, they are not able to generate sequences of feasible extractions.…”

Just-in-time code duplicates extraction

“…A considerable effort has been spent by the research community on identifying and suggesting Extract Method refactorings. The focus of these studies ranges from using program slicing techniques [30,31,41] and graph representations of code [12,23,32,35] to relying on scoring functions to find the most appropriate refactoring candidates [21,29,33,34] and using machine learning techniques [14,15,16,36]. We summarize the key studies in Table 1.…”

“…First, the pasted code fragment is parsed using the IDE's Program Structure Interface (PSI) 3 to generate its corresponding syntactic and semantic model. This model is used to calculate a set of 78 comprehensive structural and semantic metrics, previously used in various studies recommending the Extract Method refactoring [16,23,29,30,31,32,33,34,35,36]. Based on these metrics, a binary classification is performed to decide whether or not to suggest the refactoring.…”