The last line effect explained

The last line effect explained

Beller, M.M. (TU Delft Software Engineering)
Zaidman, A.E. (TU Delft Software Engineering)
Karpov, Andrey (OOO 'Program Verification Systems')
Zwaan, Rolf A. (Erasmus Universiteit Rotterdam)

2017-06

Micro-clones are tiny duplicated pieces of code; they typically comprise only few statements or lines. In this paper, we study the “Last Line Effect,” the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 219 open source projects and reporting on 263 faulty micro-clones and interviewing six authors of real-world faulty micro-clones. In an interdisciplinary collaboration, we examine the underlying psychological mechanisms for the presence of these relatively trivial errors. Based on the interviews and further technical analyses, we suggest that so-called “action slips” play a pivotal role for the existence of the last line effect: Developers’ attention shifts away at the end of a micro-clone creation task due to noise and the routine nature of the task. Moreover, all micro-clones whose origin we could determine were introduced in unusually large commits. Practitioners benefit from this knowledge twofold: 1) They can spot situations in which they are likely to introduce a faulty micro-clone and 2) they can use PVS-Studio, our automated micro-clone detector, to help find erroneous micro-clones.

Clone detection
Code clones
Interdisciplinary work
Last line effect
Micro-clones
Psychology

http://resolver.tudelft.nl/uuid:9f43b6df-e66b-4f06-8a65-a71de350a859

https://doi.org/10.1007/s10664-016-9489-6

1382-3256

Empirical Software Engineering, 22 (3), 1508-1536

Institutional Repository

journal article

© 2017 M.M. Beller, A.E. Zaidman, Andrey Karpov, Rolf A. Zwaan