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An experimental investigation on the effects of context on source code identifiers splitting and expansion

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Abstract

Recent and past studies indicate that source code lexicon plays an important role in program comprehension. Developers often compose source code identifiers with abbreviated words and acronyms, and do not always use consistent mechanisms and explicit separators when creating identifiers. Such choices and inconsistencies impede the work of developers that must understand identifiers by decomposing them into their component terms, and mapping them onto dictionary, application or domain words. When software documentation is scarce, outdated or simply not available, developers must therefore use the available contextual information to understand the source code. This paper aims at investigating how developers split and expand source code identifiers, and, specifically, the extent to which different kinds of contextual information could support such a task. In particular, we consider (i) an internal context consisting of the content of functions and source code files in which the identifiers are located, and (ii) an external context involving external documentation. We conducted a family of two experiments with 63 participants, including bachelor, master, Ph.D. students, and post-docs. We randomly sampled a set of 50 identifiers from a corpus of open source C programs and we asked participants to split and expand them with the availability (or not) of internal and external contexts. We report evidence on the usefulness of contextual information for identifier splitting and acronym/abbreviation expansion. We observe that the source code files are more helpful than just looking at function source code, and that the application-level contextual information does not help any further. The availability of external sources of information only helps in some circumstances. Also, in some cases, we observe that participants better expanded acronyms than abbreviations, although in most cases both exhibit the same level of accuracy. Finally, results indicated that the knowledge of English plays a significant effect in identifier splitting/expansion. The obtained results confirm the conjecture that contextual information is useful in program comprehension, including when developers split and expand identifiers to understand them. We hypothesize that the integration of identifier splitting and expansion tools with IDE could help to improve developers’ productivity.

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Notes

  1. http://www.gnu.org

  2. http://www.linux.org

  3. http://www.freebsd.org

  4. http://www.acronymfinder.com

  5. Significant p-values are highlighted in bold face here and in all other tables.

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Acknowledgements

Special thanks to all the participants as this work would not be ossible without your time. Many thanks also to all the reviewers for their thorough and well considered reviews.

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Authors and Affiliations

  1. SOCCER Lab., DGIGL, École Polytechnique de Montréal, QC, Canada

    Latifa Guerrouj, Yann-Gaël Guéhéneuc & Giuliano Antoniol

  2. University of Sannio, Sannio, Italy

    Massimiliano Di Penta

Authors
  1. Latifa Guerrouj
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  2. Massimiliano Di Penta
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  3. Yann-Gaël Guéhéneuc
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  4. Giuliano Antoniol
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Corresponding author

Correspondence to Latifa Guerrouj.

Additional information

Communicated by: Martin Robillard

Appendices

Appendix

A Detailed Study Settings

Table 20 reports the characteristics of the 34 applications from which the 50 identifiers used in our study were sampled.

Table 20 Applications from which the 50 identifiers were sampled
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Table 21 reports the expansions of all the identifiers used in the experiments. The column Separator indicates whether underscore or Camel Case separators are used. The columns Abbr., Acro. and Plain report the number of abbreviations, acronyms and plain English words composing each identifier.

Table 21 Splitting/expansion oracle and kinds of terms composing identifiers
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B Detailed Results

This Appendix reports figures detailing results presented and discussed in Section 3. Specifically, Figs. 7 and 8 show boxplots of Precision and Recall for the different levels of context, respectively.

Fig. 7
figure 7

Boxplots of precision different context levels (AF = Acronym Finder)

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Fig. 8
figure 8

Boxplots of recall different context levels (AF = Acronym Finder)

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Guerrouj, L., Di Penta, M., Guéhéneuc, YG. et al. An experimental investigation on the effects of context on source code identifiers splitting and expansion. Empir Software Eng 19, 1706–1753 (2014). https://doi.org/10.1007/s10664-013-9260-1

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