Abstract
Both common coupling and pointer variables can exert a deleterious effect on the quality of software. The situation is exacerbated when global variables are assigned to pointer variables, that is, when an alias to a global variable is created. When this occurs, the number of global variables increases, and it becomes considerably harder to compute quality metrics correctly. However, unless aliasing is taken into account, variables may incorrectly appear to be unreferenced (neither defined nor used), or to be used without being defined. These ideas are illustrated by means of a case study of common coupling in the Linux kernel.
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Notes
This and other references to the Linux source code refer to kernel version 2.4.20, in order to be able to draw comparisons with previous studies, especially (Yu et al., 2004).
In what follows, for brevity we use the informal terminology “fields of task_struct” rather than the more precise “fields of instances of type task_struct.”
More precisely, what has been created is a reference to an existing global variable. From the viewpoint of a programmer, however, the effect is as if a new global variable has been created.
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D. G. Feitelson: On sabbatical leave from Hebrew University.
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Schach, S.R., Adeshiyan, T.O.S., Balasubramanian, D. et al. Common coupling and pointer variables, with application to a Linux case study. Software Qual J 15, 99–113 (2007). https://doi.org/10.1007/s11219-006-9005-0
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DOI: https://doi.org/10.1007/s11219-006-9005-0