Do code clones matter?

Juergens, Elmar; Deissenboeck, Florian; Hummel, Benjamin; Wagner, Stefan

doi:10.1109/icse.2009.5070547

Cited by 325 publications

(210 citation statements)

References 31 publications

(70 reference statements)

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“…Even parts of preconditions or postconditions can be refined, which would otherwise require to clone contracts and modify them. Such specification clones may lead to similar problems as code clones [14]. For example, when updating a contract, we may forget to update clones of this contract and introduce inconsistencies.…”

Section: Consecutive Contract Refinementmentioning

confidence: 99%

Applying Design by Contract to Feature-Oriented Programming

Thüm

Schaefer

Kuhlemann

et al. 2012

Fundamental Approaches to Software Engineering

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Abstract. Feature-oriented programming (FOP) is an extension of object-oriented programming to support software variability by refining existing classes and methods. In order to increase the reliability of all implemented program variants, we integrate design by contract (DbC) with FOP. DbC is an approach to build reliable object-oriented software by specifying methods with contracts. Contracts are annotations that document and formally specify behavior, and can be used for formal verification of correctness or as test oracles. We present and discuss five approaches to define contracts of methods and their refinements in FOP. Furthermore, we share our insights gained by performing five case studies. This work is a foundation for research on the analysis of feature-oriented programs (e.g., for verifying functional correctness or for detecting feature interactions).

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Section: Consecutive Contract Refinementmentioning

confidence: 99%

Applying Design by Contract to Feature-Oriented Programming

Thüm

Schaefer

Kuhlemann

et al. 2012

Fundamental Approaches to Software Engineering

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“…We employed the latter algorithm. ConQAT has been used in various studies on clone detection (Juergens et al, 2009;Juergens et al, 2010a) including the study we build on Juergens, Deissenboeck & Hummel (2010b).…”

Section: Clone Detection Toolsmentioning

confidence: 99%

How are functionally similar code clones syntactically different? An empirical study and a benchmark

Wagner

Abdulkhaleq

Bogicevic

et al. 2016

PeerJ Computer Science

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Background. Today, redundancy in source code, so-called ''clones'' caused by copy &paste can be found reliably using clone detection tools. Redundancy can arise also independently, however, not caused by copy&paste. At present, it is not clear how only functionally similar clones (FSC) differ from clones created by copy&paste. Our aim is to understand and categorise the syntactical differences in FSCs that distinguish them from copy&paste clones in a way that helps clone detection research. Methods. We conducted an experiment using known functionally similar programs in Java and C from coding contests. We analysed syntactic similarity with traditional detection tools and explored whether concolic clone detection can go beyond syntax. We ran all tools on 2,800 programs and manually categorised the differences in a random sample of 70 program pairs. Results. We found no FSCs where complete files were syntactically similar. We could detect a syntactic similarity in a part of the files in <16% of the program pairs. Concolic detection found 1 of the FSCs. The differences between program pairs were in the categories algorithm, data structure, OO design, I/O and libraries. We selected 58 pairs for an openly accessible benchmark representing these categories. Discussion. The majority of differences between functionally similar clones are beyond the capabilities of current clone detection approaches. Yet, our benchmark can help to drive further clone detection research.

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“…However, to reduce the number of falsepositives, all approaches are in need of specifying a minimal code clone length for their unit of measurement (be it tokens, statements, lines or AST nodes) when applied in practice. This minimal clone length is usually in the range of 5-10 units (Bellon et al 2007;Juergens et al 2009), which makes it too long to detect our micro-clones of length 2 to 5 units.…”

Section: Why Current Clone Detectors Are Not Suitablementioning

confidence: 99%

The last line effect explained

Beller

Zaidman

Karpov³

et al. 2016

Empir Software Eng

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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.

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Do code clones matter?

Cited by 325 publications

References 31 publications

Applying Design by Contract to Feature-Oriented Programming

Applying Design by Contract to Feature-Oriented Programming

How are functionally similar code clones syntactically different? An empirical study and a benchmark

The last line effect explained

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