Awesome
Keep Cognitive Complexity Down
<br>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.
<br>Install
composer require tomasvotruba/cognitive-complexity --dev
The package is available on PHP 7.4+.
<br>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
<br>
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:
# phpstan.neon
parameters:
cognitive_complexity:
dependency_tree: 150
dependency_tree_types:
# only these explicit types are checked, nothing else
- Rector\Contract\Rector\RectorInterface
<br>
Happy coding!