Metrics
Along with Architectural Smells, Arcan computes a set of software metrics. This page reports the complete list of the metrics that can be computed with Arcan.
| Name | Scope | Definition | Ref |
|---|---|---|---|
| Abstractness | Package | The number of abstract classes (and interfaces) divided by the total number of types in a package. This metric range is [0,1], where 0 indicates a completely concrete package and 1 indicates a completely abstract package. | [1] |
| Instability | Package | The package’s resilience to change. This metric range is [0,1], where 0 indicates that the package is completely stable and 1 completely unstable. This metric range is [0,1], where 0 indicates that the package is directly on the main sequence whereas 1 indicates that the package is as far away as possible from the main sequence. Small numbers are indicators of good packaging design. | [1] |
| Distance from main sequence | Package | The package’s balance between abstractness and stability. | [1] |
| Fan In | Package, Class | The number of ingoing dependences of a class. | [1] |
| Fan Out | Package, Class | The number of outgoing dependences of a class. | [1] |
| Lines of code | Package, Class | The number of lines of code of a given class or package. The metric does not count blank lines and commented lines. | - |
| Change has occurred (CHO) | Package, Class | Given the project history (Git commits), it measures whether a class or package has changed or not in the current commit with respect to the previous commit. | [2] |
| Code churn (TACH) | Package, Class | Givent the history of a project (git commits), it is the sum of added lines of code, deleted lines, and twice the changed lines since the last commit for a given class or package. | [2] |
| PageRank | Package, Class | Estimates whether an architectural smell is located in an important part of the project, where the importance is evaluated according to how many parts of a project depend on the one involved in the architectural smell. The metric is based on the one implemented by Brin and Page. | [3] |
| Coupling between objects | Class | Number of classes to which a class is coupled, that is the number of classes that a class references. The coupling beetween classes should be low, otherwise it will difficult to make changes to the system without change a lot of classes. | [4] |
| Depth of inheritance | Class | The depth of inheritance tree (DIT) is a code metric that is specific to object-oriented programming. It measures the maximum length between a node and the root node in a class hierarchy. The minimum value of DIT for a class is 1. The metric range is [0, infinite]. 0 indicates a root. The minimum value for a class is 1. A value > 1 indicates that there is code reuse through inheritance. If there is a majority of values below 2, it may represent poor exploitation of the advantages of OO design and inheritance. It is recommended a maximum value of 5 since deeper trees constitute greater design complexity. | [4] |
| Number of children | Class | The number of classes inheriting from a given class. | [4] |
| Number of architectural smells | Project | The total number of architectural smells detected by Arcan in the analysed project. | - |
| Number of components | Project | The sum of number of classes and packages of the analysed project. | - |
[1] R. C. Martin, J. Grenning, S. Brown, K. Henney, and J. Gorman, Clean architecture: a craftsman’s guide to software structure and design. Prentice Hall, 2018.
[2] M. O. Elish and M. A. R. Al-Khiaty, “A suite of metrics for quantifying historical changes to predict future change-prone classes in object-oriented software,” Journal of software: Evolution and Process, vol. 25, pp. 407–437, may 2013.
[3] R. Roveda, F. A. Fontana, I. Pigazzini, and M. Zanoni, “Towards an architectural debt index,” in Proceedings - 44th Euromicro Conference on Software Engineering and Advanced Applications, SEAA 2018, pp. 408–416, IEEE, aug 2018.
[4] S. R. Chidamber and C. F. Kemerer, “A metrics suite for object oriented designa metrics suite for object oriented design,” PhD Proposal, vol. 1, pp. 476–493, 1992.