OASIS Static Analysis Results Interchange Format (SARIF) TC

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  • 1.  Followup on code metrics

    Posted 10-01-2021 18:20




    All:
     
    I m following up on our meeting yesterday with some material on code metrics.
     
    There are a couple of metric families that are commonly used. The first are simple line counts. It s common for tools to have several varieties such as raw lines, non-blank lines, lines with comments, etc. There are also a few metrics
    that count syntactic constructs in various ways, such as nesting depth.
     
    Then there is the McCabe family which contains the much misunderstood Cyclomatic Complexity and a few relatives that attempt to compensate for its shortcomings; e.g. Essential Complexity, and Module Design Complexity.
     
    The Halstead metrics are an antiquated family that are based on counting tokens in various ways. They don t appear to be widely used any more.
     
    There are a bunch of Object-oriented metrics that are often about the relationship between classes: coupling, cohesion, etc.
     
    I mentioned metrics used in the embedded industry and how there s a need for this to be more standardized. A metrics collection that seems to be popular in automotive is the HIS/KGAS set
    https://docplayer.net/6136232-His-source-code-metrics.html . Here s a blog I wrote a little while ago that picks on one particular metric used in that set:
    https://blogs.grammatech.com/why-npath-is-a-terrible-code-metric .
     
    As I said in the meeting, metrics have numeric values, but we should also allow for exceptional results. For example:

    Computing the metric leads to a numeric error such as divide by zero The metric can t be computed because it s inapplicable for some reason The value can t be reasonably expressed (e.g., a path count metric can easily yield 30-40 digit decimal values) The value is infinity (which
    kind of infinity probably doesn t matter
    ð )
    There s some overlap between these of course. I ve seen them all in real life.
     
    -Paul
     
     
    --

    Paul Anderson, VP of Engineering, GrammaTech, Inc.
    531 Esty St., Ithaca, NY 14850
    Tel: +1 607 273-7340 x118;
    https://www.grammatech.com
     



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