Slevomat Coding Standard

Slevomat Coding Standard is a collection of sniffs for PHP_CodeSniffer. The sniffs are categorized into three main types to help maintain high-quality PHP codebases:

• Functional: Improves the safety and behavior of your code.
• Cleaning: Detects dead code that can be removed.
• Formatting: Ensures consistent code appearance and style.

Yoda conditions (e.g., if (true === $variable)) can be managed using two opposing sniffs:

1. SlevomatCodingStandard.ControlStructures.DisallowYodaComparison: Disallows Yoda conditions and looks for/fixes them throughout the code.
2. SlevomatCodingStandard.ControlStructures.RequireYodaComparison: Requires the use of Yoda conditions.

If using RequireYodaComparison, you can use the alwaysVariableOnRight setting (default: false) to move variables to the right side of the operator.

The Slevomat Coding Standard provides a wide array of PHP sniffs to enforce coding styles and best practices. When browsing the list of available sniffs, you can identify their capabilities using specific icons:

• 🔧 Automatic error fixing: These sniffs can automatically fix the detected coding standard violations (e.g., via phpcs with --fix or similar tools).
• 🚧 Local suppression: These sniffs can be suppressed locally in your code if a specific instance requires an exception to the rule.

The recommended installation method is using Composer. Add slevomat/coding-standard to your require-dev section.

It is also highly recommended to install php-parallel-lint/php-parallel-lint to check for syntax errors before running sniffs. Sniffs require syntactically valid code to behave predictably. You should run PHP-Parallel-Lint in your build pipeline before PHP_CodeSniffer and exit early if it fails.

{
	"require-dev": {
		"slevomat/coding-standard": "~8.0"
	}
}

If you need to ignore a specific sniff violation for a particular piece of code, you can use the @phpcsSuppress annotation. Sniffs that support this are marked with the 🚧 symbol.

To suppress an error, use its full error code (e.g., SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingNativeTypeHint) in the annotation.

/**
 * @phpcsSuppress SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingNativeTypeHint
 * @param int $max
 */
public function createProgressBar($max = 0): ProgressBar
{

}

Sniffs marked with the 🔧 symbol support automatic fixing. To apply these fixes to your codebase, run phpcbf instead of phpcs using your ruleset.xml.

Note: Always back up your code before running automatic fixes and manually verify the results, as the fixer can occasionally produce unexpected output.

vendor/bin/phpcbf --standard=ruleset.xml --extensions=php --tab-width=4 -sp src tests

To run only specific sniffs from the standard, create a custom ruleset.xml file. In this file, use the <config name="installed_paths" ... /> tag to point to the Slevomat Coding Standard location (relative to your PHPCS source) and then reference the specific sniffs you want to include using the <rule ref="..."/> tag.

Once configured, run phpcs pointing to your ruleset.

<?xml version="1.0"?>
<ruleset name="AcmeProject">
	<config name="installed_paths" value="../../slevomat/coding-standard"/><!-- relative path from PHPCS source location -->
	<rule ref="SlevomatCodingStandard.Arrays.TrailingArrayComma"/>
	<!-- other sniffs to include -->
</ruleset>

vendor/bin/phpcs --standard=ruleset.xml --extensions=php --tab-width=4 -sp src tests

You can include the entire Slevomat Coding Standard in your ruleset.xml and then exclude specific sniffs.

Warning: This is not the recommended approach. Because the standard adds new sniffs in minor versions, your builds may break if you use version constraints like ^ or ~ in composer.json. It is better to explicitly include only the sniffs you want.

<?xml version="1.0"?>
<ruleset name="AcmeProject">
	<rule ref="vendor/slevomat/coding-standard/SlevomatCodingStandard/ruleset.xml"><!-- relative path to your ruleset.xml -->
		<!-- sniffs to exclude -->
	</rule>
</ruleset>

The SlevomatCodingStandard.Operators.SpreadOperatorSpacing sniff enforces a configurable number of spaces after the ... (spread) operator.

Settings:

• spacesCountAfterOperator: The number of spaces required after the ... operator.

Use SlevomatCodingStandard.TypeHints.DeclareStrictTypes to ensure every PHP file includes the declare(strict_types = 1) statement.

Settings:

• declareOnFirstLine: Requires the declaration to be on the first line immediately after <?php.
• linesCountBeforeDeclare: Number of lines allowed between <?php and the declare statement (ignored if declareOnFirstLine is enabled).
• linesCountAfterDeclare: Number of lines allowed between the declare statement and the next statement.
• spacesCountAroundEqualsSign: Number of required spaces around the = operator.

Use SlevomatCodingStandard.Attributes.DisallowAttributesJoining to ensure that each attribute is placed inside its own #[] block. This prevents comma-separated lists like #[AttributeOne, AttributeTwo] and forces them to be split into individual blocks like:

#[AttributeOne]
#[AttributeTwo]