"Cloning Considered Harmful" Considered Harmful

Kapser, Cory; Godfrey, Michael W.

doi:10.1109/wcre.2006.1

Cited by 185 publications

(126 citation statements)

References 29 publications

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“…They also proposed a tool support for the comprehension of software clones [28]. Kapser and Godfrey [29] also presented a taxonomy of cloning patterns, describing for each pattern the motivation, the pros and cons, the way clones manifest in the code structure, and clone management issues. Each pattern is described using examples detected in large software systems such as the Linux Kernel or the Apache Web server.…”

Section: Empirical Studies On the Presence And Evolution Of Clonesmentioning

confidence: 99%

An empirical study on the maintenance of source code clones

et al. 2009

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Code cloning has been very often indicated as a bad software development practice. However, many studies appearing in the literature indicate that this is not always the case. In fact, either changes occurring in cloned code are consistently propagated, or cloning is used as a sort of templating strategy, where cloned source code fragments evolve independently. This paper (i) proposes an automatic approach to classify the evolution of source code clone fragments, and (ii) reports a fine-grained analysis of clone evolution in four different Java and C software systems, aimed at investigating to what extent clones are consistently propagated or they evolve independently. Also, the paper investigates the relationship between the presence of clone evolution patterns and other characteristics such as clone raSuresh Thummalapenta North Carolina State University, Raleigh, USA E-mail: sthumma@ncsu.edu Luigi Cerulo, Lerina Aversano, Massimiliano Di Penta Department of Engineering -University of Sannio, Benevento, Italy E-mail: lcerulo@unisannio.it, aversano@unisannio.it, dipenta@unisannio.it 2 dius, clone size and the kind of change the clones underwent, i.e., corrective maintenance or enhancement.

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Section: Empirical Studies On the Presence And Evolution Of Clonesmentioning

confidence: 99%

An empirical study on the maintenance of source code clones

et al. 2009

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“…Although cloning is beneficial in some cases [13] and often programmers intentionally use it [17], it can be detrimental to software maintenance [8,12]. For example, if a bug is detected in a code fragment, all the fragments similar to it should be investigated to check for the same bug [19], and when enhancing or adapting a piece of code, duplicated fragments can multiply the work to be done [12].…”

Section: Introductionmentioning

confidence: 99%

An Empirical Study of Function Clones in Open Source Software

Roy

Cordy

2008

2008 15th Working Conference on Reverse Engineering

104

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The new hybrid clone detection tool NICAD combines the strengths and overcomes the limitations of both textbased and AST-based clone detection techniques to yield highly accurate identification of cloned code in software systems. In this paper, we present a first empirical study of function clones in open source software using NICAD. We examine more than 15 open source C and Java systems, including the entire Linux Kernel and Apache httpd, and analyze their use of cloned code in several different dimensions, including language, clone size, clone location and clone density by proportion of cloned functions. We manually verify all detected clones and provide a complete catalogue of different clones in an online repository in a variety of formats. These validated results can be used as a cloning reference for these systems and as a benchmark for evaluating other clone detection tools.

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“…Second, besides source code with pervasive modifications, we compared the similarity analysers on an available data set containing reuse of boiler-plate code, and a data set of boiler-plate code with pervasive modifications. Since boiler-plate code is inherently different from pervasively modified code and normally found in software development (Kapser 2006), the findings give a guideline to choosing the right tools/techniques when measuring code similarity in the presence of boiler-plate code. Third, we investigated the effects of reusing optimal configurations from one data set on another data set.…”

Section: Contributionsmentioning

confidence: 99%

“…1 Boiler-plate code occurs when developers reuse a code template, usually a function or a code block, to achieve a particular task. It has been defined as one of the code cloning patterns by (Kapser 2006;Kapser and Godfrey 2008). Boiler-plate code can be found when building device drivers for operating systems (Baxter et al 1998), developing android applications , and giving programming assignments (Burrows et al 2007;Schleimer et al 2003).…”

Section: Source Code Modificationsmentioning

confidence: 99%

A comparison of code similarity analysers

2017

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Copying and pasting of source code is a common activity in software engineering. Often, the code is not copied as it is and it may be modified for various purposes; e.g. refactoring, bug fixing, or even software plagiarism. These code modifications could affect the performance of code similarity analysers including code clone and plagiarism detectors to some certain degree. We are interested in two types of code modification in this study: pervasive modifications, i.e. transformations that may have a global effect, and local modifications, i.e. code changes that are contained in a single method or code block. We evaluate 30 code similarity detection techniques and tools using five experimental scenarios for Java source code. These are (1) pervasively modified code, created with tools for source code and bytecode obfuscation, and boiler-plate code, (2) source code normalisation through compilation and decompilation using different decompilers, (3) reuse of optimal configurations over different data sets, (4) tool evaluation using ranked-based measures, and (5) local + global code modifications. Our experimental results show that in the presence of pervasive modifications, some of the general textual similarity measures can offer similar performance to specialised code similarity tools, whilst in the presence of boiler-plate code, highly specialised source code similarity detection techniques and tools outperform textual similarity measures. Our study strongly validates the use of compilation/decompilation as a normalisation technique. Its use reduced false classifications to zero for three of the tools. Moreover, we demonstrate that optimal configurations are very sensitive to a specific data set. After directly applying optimal configurations derived from one data set to another, the tools perform poorly on the new data set. The code similarity analysers are thoroughly evaluated not only based on several well-known pair-based and query-based error measures but also on each specific type of pervasive code modification. This broad, thorough study is the largest in existence and potentially an invaluable guide for future users of similarity detection in source code.

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"Cloning Considered Harmful" Considered Harmful

Abstract: Current literature on the topic of duplicated (cloned)

Cited by 185 publications

References 29 publications

An empirical study on the maintenance of source code clones

An empirical study on the maintenance of source code clones

An Empirical Study of Function Clones in Open Source Software

A comparison of code similarity analysers

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