https://github.com/tomasvotruba/cognitive-complexity

PHPStan rules to measure cognitive complexity of your classes and methods
https://github.com/tomasvotruba/cognitive-complexity

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PHPStan rules to measure cognitive complexity of your classes and methods

• Host: GitHub
• URL: https://github.com/tomasvotruba/cognitive-complexity
• Owner: TomasVotruba
• License: mit
• Created: 2022-12-23T12:16:31.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-01-03T13:13:16.000Z (9 months ago)
• Last Synced: 2024-10-01T08:49:02.750Z (2 days ago)
• Language: PHP
• Homepage: https://tomasvotruba.com/blog/keep-cognitive-complexity-low-with-phpstan/
• Size: 108 KB
• Stars: 107
• Watchers: 5
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
# Keep Cognitive Complexity Down




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

**How is cognitive complexity measured?**

```php

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](https://tomasvotruba.com/blog/keep-cognitive-complexity-low-with-phpstan/) post to learn it.




## Install

```bash

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](https://github.com/phpstan/extension-installer), everything is ready to run.

Enable each item on their own with simple configuration:

```neon

# phpstan.neon

parameters:

    cognitive_complexity:

        class: 50

        function: 8

```




## Detect complex Class Dependency Trees

In classes like controllers, Rector rules, PHPStan rules or other services of specific type, the complexity can be hidden in the __construct() dependencies. Simple class with 10 dependencies is more complex than complex class with 2 dependencies.

That's why there is a rule to detect these dependency trees. It checks:

* complexity of **current class**

* **constructor dependencies and their class complexity** together

Final number is compared and used as a final complexity:

```neon

# phpstan.neon

parameters:

    cognitive_complexity:

        dependency_tree: 150

        dependency_tree_types:

            # only these explicit types are checked, nothing else

            - Rector\Contract\Rector\RectorInterface

```




Happy coding!