Variability through the Eyes of the Programmer

Jean Melo, Fabricio Batista Narcizo, Dan Witzner Hansen, Claus Brabrand, Andrzej Wasowski

Research output: Conference Article in Proceeding or Book/Report chapterArticle in proceedingsResearchpeer-review


Preprocessor directives (#ifdefs) are often used to implement compile-time variability, despite the critique that they increase complexity, hamper maintainability, and impair code comprehensibility. Previous studies have shown that the time of bug finding increases linearly with variability. However, little is known about the cognitive process of debugging programs with variability. We carry out an experiment to understand how developers debug programs with variability. We ask developers to debug programs with and without variability, while recording their eye movements using an eye tracker. The results indicate that debugging time increases for code fragments containing variability. Interestingly, debugging time also seems to increase for code fragments without variability in the proximity of fragments that do contain variability. The presence of variability correlates with increase in the number of gaze transitions between definitions and usages for fields and methods. Variability also appears to prolong the "initial scan" of the entire program that most developers initiate debugging with.
Original languageEnglish
Title of host publication2017 IEEE/ACM 25th International Conference on Program Comprehension (ICPC)
Number of pages11
Publication date1 May 2017
ISBN (Electronic)978-1-5386-0535-6
Publication statusPublished - 1 May 2017
Event2017 IEEE/ACM 25th International Conference on Program Comprehension - Buenos Aires, Buenos Aires, Argentina
Duration: 22 May 201723 May 2017
Conference number: 25th


Conference2017 IEEE/ACM 25th International Conference on Program Comprehension
LocationBuenos Aires
CityBuenos Aires
Internet address


  • cognition
  • gaze tracking
  • human factors
  • program compilers
  • program debugging
  • software maintenance
  • code comprehensibility
  • code fragments
  • cognitive process
  • compile-time variability
  • debugging time
  • eye movements
  • eye tracker
  • gaze transitions
  • preprocessor directives
  • software maintainability
  • Complexity theory
  • Computer bugs
  • Debugging
  • Games
  • Open source software
  • Tools
  • Tracking
  • Eye Tracking
  • Highly-Configurable Systems
  • Preprocessors
  • Variability


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