  Collaborative software development happens in teams, that cooperate on shared
artefacts, and discuss development on online platforms. Due to the complexity
of development and the variety of teams, software components often act as
effective containers for parallel work and teams.
  Past research has shown how communication between team members, especially in
an open-source environment, can become extremely toxic, and lead to members
leaving the development team. This has a direct effect on the evolution and
maintenance of the project in which the former members were active in.
  The purpose of our study is two-fold: first, we propose an approach to
evaluate, at a finer granularity, the positive and negative emotions in the
communication between developers; and second, we aim to characterise a
project's development paths, or components, as more or less impacted by the
emotions.
  Our analysis evaluates single sentences rather than whole messages as the
finest granularity of communication. The previous study found that the high
positivity or negativity at the sentence level may indirectly impact the writer
him/herself, or the reader. In this way, we could highlight specific paths of
Gentoo as the most affected by negative emotions, and show how negative
emotions have evolved and changed along the same paths.
  By joining the analysis of the mailing lists, from which we derive the
sentiment of the developers, with the information derived from the development
logs, we obtained a longitudinal picture of how development paths have been
historically affected by positive or negative emotions. Our study shows that,
in recent years, negative emotions have generally decreased in the
communication between Gentoo developers. We also show how file paths, as
collaborative software development artefacts, were more or less impacted by the
emotions of the developers.
