Code Analysis with PHP Metrics

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Presented by Chris Gmyr @cmgmyr

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Installation composer global require phpmetrics/phpmetrics

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Generate Report phpmetrics --report-html=myreport /path/of/src

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Laravel git clone git@github.com:laravel/laravel.git phpmetrics --report-html=laravel_metrics laravel

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What Are We Going to Learn? 4 Maintainability 4 Violations 4 Complexity 4 Relationships

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But First, Some Vocabulary! !

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Cyclomatic Complexity The cyclomatic complexity of a section of source code is the number of linearly independent paths within it. 4 If the source code contained no control flow statements (conditionals or decision points), the complexity would be 1. 4 One IF statement = two paths through the code, complexity would be 2. 4 Two nested single-condition IFs, or one IF with two conditions, would produce a complexity of 3. https://en.wikipedia.org/wiki/Cyclomatic_complexity

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More Conditionals & Statements = More Complex

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Lower Score is Better!

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Halstead Complexity Measures Observation that metrics of the software should reflect the implementation or expression of algorithms in different languages, but be independent of their execution on a specific platform. https://en.wikipedia.org/wiki/ Halstead_complexity_measures http://www.verifysoft.com/en_halstead_metrics.html

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Lower Score is Better!

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Maintainability Index Provides a score between 0 to 118. Halstead's metrics, LOC and Cyclomatic complexity number. General scores: 4 <64: low maintainability. The project has probably technical debt. 4 65-84: medium maintainability. The project has problems, but nothing really serious. 4 >85: high maintainability. The project is probably good.

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Higher Score is Better!

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Let's Explore!

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Violations

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Size & Volume

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Complexity & Defects

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Object Oriented Metrics

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Object Relations

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Coupling

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Takeaways 1. More Classes 2. Smaller Classes 3. Simpler Classes 4. Loosely Coupled Classes