mirror of https://gitlab.com/basile.b/dexed.git
62 lines
2.3 KiB
Markdown
62 lines
2.3 KiB
Markdown
---
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title: Options - Code Metrics
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header-includes: <script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/4.2.2/anchor.min.js"></script>
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---
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The quality of the D code is verifiable using code metrics.
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In general several metrics exist:
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* simple Source Line of Code (SLOC), white lines and comment counter.
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* [Halstead complexity](https://en.wikipedia.org/wiki/Halstead_complexity_measures): quality indicator based on the count of operators and operands.
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* [Cyclomatic complexity](https://en.wikipedia.org/wiki/Cyclomatic_complexity): quality indicator based on the program execution flow.
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Dexed implements the Halstead metric. The others may be added in a further version.
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## Halstead complexity
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The metric uses the count and the sum of the functions operands and operators to compute several indexes. Even it's clearly related to the SLOC it's more accurate. For example:
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```d
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void foo()
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{
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int a = 1, b;
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a = a + a;
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}
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```
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Is seen as less complex than
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```d
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void foo()
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{
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int a = 1, b;
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a = a + b++;
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}
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```
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even if the SLOC count is the same.
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The verification is launched from the _File_ menu, _View Halstead metrics_.
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Each free function and member function of the module that has the focus is measured.
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When thresholds are crossed warnings are emitted. There is 3 possible warnings:
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* the maximal estimated number of bugs per function is reached, by default 0.5.
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* the maximal estimated number of bugs per module is reached, by default 2.
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* the maximal volume of a function is reached, by default 2000.
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Warnings are informative. They should simply be interpreted as an indicator that a function must be more tested or refactorized.
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It's important to note the limits of the measure:
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* even with D embedded unit tests, the measure is not able to detect that a complex function is well tested.
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* the evolution of the quality over the time is not followed-up.
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* results are only relevant with the _imperative_ and _object oriented_ programming paradigm. Template Meta Programming will give wrong results. UFCS chain are not detected as consecutive calls.
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Default values can be modified in the option editor:
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The maximal volume of a module is not verified, simply because it's possible to have huge modules with many small functions of high quality.
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