Keep Cognitive Complexity Down

Cognitive complexity tells us, how difficult code is to understand by a reader.

How is cognitive complexity measured?

function get_words_from_number(int $number): string
{
    $amountInWords = '';

    if ($number === 1) {            // + 1
        $amountInWords = 'one';
    } elseif ($number === 2) {      // + 1
        $amountInWords = 'couple';
    } elseif ($number === 3) {      // + 1
        $amountInWords = 'a few';
    } else {                        // + 1
        $amountInWords = 'a lot';
    }

    return $amountInWords;
}

This function uses nesting, conditions and continue back and forth. It's hard to read and results in cognitive complexity of 4.

How to keep cognitive complexity on 1? Read Keep Cognitive Complexity Low with PHPStan post to learn it.

Install

composer require tomasvotruba/cognitive-complexity --dev

The package is available on PHP 7.2-8.1 versions in tagged releases.

Usage

With PHPStan extension installer, everything is ready to run.

Enable each item on their own with simple configuration:

# phpstan.neon
parameters:
    cognitive_complexity:
        class: 50
        function: 8