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Chapter 6. Change Dynamics
However, a serious investigation of change at higher level of abstraction
remains to be done and we intend to consider it in future work.
6.5 Limitations
In order to place our study in context, we highlight some of the known
limitations of our approach in addition to our findings.
The change detection method used in this work may miss a small set
of classes if the change is not measurable in the metrics under consideration.
The accuracy can be improved by adding further metrics
and additional aspects like a comparison of the call graph. The value
of this additional complexity remains as a topic for consideration in our
future work. Furthermore, our distance measure compares the initial
version of a class to the final version. This method will miss edits where
a class is modified and returned back to its original shape, as seen by
our change detection technique. This limitation can be addressed by
computing a distance measure incrementally. As a consequence, the
analysis approach will need to be adjusted to take into consideration
the way the metric information is being collected.
Our method of computing modification misses classes that have been
renamed; they will be considered as a deletion (in the earlier version)
and an addition (to the later version). However, of the few classes that
are deleted (less than 4% in general), a subset might be class renames.
We checked if a class has indeed been renamed manually in 300 randomly
selected instances. Less than 5% of the classes that we checked
can be considered refactored with a name change. Based on this observation,
the benefit from using a complex algorithm to detect renamed
classes is likely to have at best a minimal overall impact and our overall
conclusions and recommendations will still hold.
We have also not investigated in depth why changing classes have higher
than normal In-Degree Count. We speculate that the introduction of
new clients creates the need for adaptations. Other possibilities are
that (i) new clients introduce new requirements, but that suggests new
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