Slevomat Coding Standard

Slevomat Coding Standard for PHP_CodeSniffer provides sniffs that fall into three categories:

• Functional - improving the safety and behaviour of code
• Cleaning - detecting dead code
• Formatting - rules for consistent code looks

Table of contents

1. Sniffs included in this standard

• Functional - improving the safety and behaviour of code
• Cleaning - detecting dead code
• Formatting - rules for consistent code looks

2. Installation
3. How to run the sniffs

• Choose which sniffs to run
• Using all sniffs from the standard

4. Fixing errors automatically
5. Suppressing sniffs locally
6. Contributing

Sniffs included in this standard

🔧 = Automatic errors fixing

🚧 = Sniff check can be suppressed locally

Functional - improving the safety and behaviour of code

SlevomatCodingStandard.TypeHints.TypeHintDeclaration 🔧🚧

• Checks for missing property types in phpDoc @var.
• Checks for missing typehints in case they can be declared natively. If the phpDoc contains something that can be written as a native PHP 7.0, 7.1 or 7.2 typehint, this sniff reports that.
• Checks for missing @return and/or native return typehint in case the method body contains return with a value.
• Checks for useless doc comments. If the native method declaration contains everything and the phpDoc does not add anything useful, it's reported as useless and can optionally be automatically removed with phpcbf.
• Some phpDocs might still be useful even if they do not add any typehint information. They can contain textual descriptions of code elements and also some meaningful annotations like @expectException or @dataProvider.
• Forces to specify what's in traversable types like array, iterable and \Traversable.

Sniff provides the following settings:

• DEPRECATED enableNullableTypeHints: enforces to transform Foo|null in phpDoc into ?Foo in native typehint.
• DEPRECATED enableVoidTypeHint: enforces to transform @return void into native void return typehint.
• enableObjectTypeHint: enforces to transform @param object or @return object into native object typehint. It's on by default if you're on PHP 7.2+
• traversableTypeHints: enforces which typehints must have specified contained type. E. g. if you set this to \Doctrine\Common\Collections\Collection, then \Doctrine\Common\Collections\Collection must always be supplied with the contained type: \Doctrine\Common\Collections\Collection|Foo[].
• usefulAnnotations: prevents reporting and removing useless phpDocs if they contain an additional configured annotation like @dataProvider.
• enableEachParameterAndReturnInspection: enables inspection and fixing of @param and @return annotations separately. Useful when you only want to document parameters or return values that could not be expressed natively (i.e. member types of array or Traversable).

This sniff can cause an error if you're overriding or implementing a parent method which does not have typehints. In such cases add @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingParameterTypeHint annotation to the method to have this sniff skip it.

SlevomatCodingStandard.Exceptions.ReferenceThrowableOnly 🔧

In PHP 7.0, a Throwable interface was added that allows catching and handling errors in more cases than Exception previously allowed. So, if the catch statement contained Exception on PHP 5.x, it means it should probably be rewritten to reference Throwable on PHP 7.x. This sniff enforces that.

SlevomatCodingStandard.TypeHints.DeclareStrictTypes 🔧

Enforces having declare(strict_types = 1) at the top of each PHP file. Allows configuring how many newlines should be between the <?php opening tag and the declare statement.

Sniff provides the following settings:

• newlinesCountBetweenOpenTagAndDeclare: allows to set 0 to N newlines to be between <?php and declare
• newlinesCountAfterDeclare: allows to set 0 to N newlines to be between declare and next statement
• spacesCountAroundEqualsSign: allows to set number of required spaces around the = operator

SlevomatCodingStandard.ControlStructures.AssignmentInCondition

Disallows assignments in if, elseif and do-while loop conditions:

if ($file = findFile($path)) {

}

Assignment in while loop condition is specifically allowed because it's commonly used.

This is a great addition to already existing SlevomatCodingStandard.ControlStructures.DisallowYodaComparison because it prevents the danger of assigning something by mistake instead of using comparison operator like ===.

SlevomatCodingStandard.ControlStructures.DisallowEqualOperators 🔧

Disallows using loose == and != comparison operators. Use === and !== instead, they are much more secure and predictable.

SlevomatCodingStandard.ControlStructures.RequireNullCoalesceOperator 🔧

Require usage of null coalesce operator when possible.

SlevomatCodingStandard.ControlStructures.EarlyExit 🔧

Require usage of early exit.

Cleaning - detecting dead code

SlevomatCodingStandard.Classes.UnusedPrivateElements 🚧

Although PHP_CodeSniffer is not suitable for static analysis because it is limited to analysing one file at a time, it is possible to use it to perform certain checks. UnusedPrivateElementsSniff checks for unused methods, unused or write-only properties in a class and unused private constants. Reported unused elements are safe to remove.

This is very useful during refactoring to clean up dead code and injected dependencies.

Sniff provides the following settings:

• alwaysUsedPropertiesAnnotations: mark certain properties as always used, for example the ones with @ORM\Column
• alwaysUsedPropertiesSuffixes: mark properties with name ending with a certain string to be always marked as used

SlevomatCodingStandard.Namespaces.UnusedUses 🔧

Looks for unused imports from other namespaces.

Sniff provides the following settings:

• searchAnnotations (defaults to false): enables searching for mentions in annotations, which is especially useful for projects using Doctrine Annotations

SlevomatCodingStandard.Namespaces.UseFromSameNamespace 🔧

Prohibits uses from the same namespace:

namespace Foo;

use Foo\Bar;

SlevomatCodingStandard.Exceptions.DeadCatch

This sniff finds unreachable catch blocks:

try {
	doStuff();
} catch (\Throwable $e) {
	log($e);
} catch (\InvalidArgumentException $e) {
	// unreachable!
}

Formatting - rules for consistent code looks

SlevomatCodingStandard.Arrays.TrailingArrayComma 🔧

Commas after last element in an array make adding a new element easier and result in a cleaner versioning diff.

This sniff enforces trailing commas in multi-line arrays and requires short array syntax [].

SlevomatCodingStandard.ControlStructures.LanguageConstructWithParentheses 🔧

LanguageConstructWithParenthesesSniff checks and fixes language construct used with parentheses.

SlevomatCodingStandard.ControlStructures.NewWithParenthesesSniff 🔧

Require new with parentheses.

SlevomatCodingStandard.ControlStructures.DisallowYodaComparison/RequireYodaComparison 🔧

Yoda conditions decrease code comprehensibility and readability by switching operands around comparison operators forcing the reader to read the code in an unnatural way.

DisallowYodaComparisonSniff looks for and fixes such comparisons not only in if statements but in the whole code.

However, if you prefer Yoda conditions, you can use RequireYodaComparisonSniff.

SlevomatCodingStandard.Namespaces.AlphabeticallySortedUses 🔧

Checks whether uses at the top of a file are alphabetically sorted. Follows natural sorting and takes edge cases with special symbols into consideration. The following code snippet is an example of correctly sorted uses:

use LogableTrait;
use LogAware;
use LogFactory;
use LoggerInterface;
use LogLevel;
use LogStandard;

Sniff provides the following settings:

• caseSensitive: compare namespaces case sensitively, which makes this order correct:

use LogAware;
use LogFactory;
use LogLevel;
use LogStandard;
use LogableTrait;
use LoggerInterface;

SlevomatCodingStandard.TypeHints.LongTypeHints 🔧

Enforces using shorthand scalar typehint variants in phpDocs: int instead of integer and bool instead of boolean. This is for consistency with native scalar typehints which also allow shorthand variants only.

SlevomatCodingStandard.Files.TypeNameMatchesFileName

For projects not following the PSR-0 or PSR-4 autoloading standards, this sniff checks whether a namespace and a name of a class/interface/trait follows agreed-on way to organize code into directories and files.

Other than enforcing that the type name must match the name of the file it's contained in, this sniff is very configurable. Consider the following sample configuration:

<rule ref="SlevomatCodingStandard.Files.TypeNameMatchesFileName">
	<properties>
		<property name="rootNamespaces" type="array" value="app/ui=>Slevomat\UI,app=>Slevomat,build/SlevomatSniffs/Sniffs=>SlevomatSniffs\Sniffs,tests/ui=>Slevomat\UI,tests=>Slevomat"/>
		<property name="skipDirs" type="array" value="components,forms,model,models,services,stubs,data,new"/>
		<property name="ignoredNamespaces" type="array" value="Slevomat\Services"/>
	</properties>
</rule>

Sniff provides the following settings:

• rootNamespaces property expects configuration similar to PSR-4 - project directories mapped to certain namespaces.
• skipDirs are not taken into consideration when comparing a path to a namespace. For example, with the above settings, file at path app/services/Product/Product.php is expected to contain Slevomat\Product\Product, not Slevomat\services\Product\Product.
• extensions: allow different file extensions. Default is php.
• ignoredNamespaces: sniff is not performed on these namespaces.

SlevomatCodingStandard.Classes.ClassConstantVisibility 🔧

In PHP 7.1+ it's possible to declare visibility of class constants. In a similar vein to optional declaration of visibility for properties and methods which is actually required in sane coding standards, this sniff also requires declaring visibility for all class constants.

Sniff provides the following settings:

• fixable: the sniff is not fixable by default because we think it's better to decide about each constant one by one however you can enable fixability with this option.

const FOO = 1; // visibility missing!
public const BAR = 2; // correct

SlevomatCodingStandard.TypeHints.ReturnTypeHintSpacing 🔧

Enforces consistent formatting of return typehints, like this:

function foo(): ?int

Sniff provides the following settings:

• spacesCountBeforeColon: the number of spaces expected between closing brace and colon.

SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue 🔧

Checks whether the nullablity ? symbol is present before each nullable and optional parameter (which are marked as = null):

function foo(
	int $foo = null, // ? missing
	?int $bar = null // correct
) {

}

SlevomatCodingStandard.TypeHints.ParameterTypeHintSpacing 🔧

• Checks that there's a single space between a typehint and a parameter name: Foo $foo
• Checks that there's no whitespace between a nullability symbol and a typehint: ?Foo

SlevomatCodingStandard.Namespaces.DisallowGroupUse

Group use declarations are ugly, make diffs ugly and this sniff prohibits them.

SlevomatCodingStandard.Namespaces.FullyQualifiedClassNameAfterKeyword 🔧

Enforces fully qualified type references after configurable set of language keywords.

For example, with the following setting, extended or implemented type must always be referenced with a fully qualified name:

<rule ref="SlevomatCodingStandard.Namespaces.FullyQualifiedClassNameAfterKeyword">
	<properties>
		<property name="keywordsToCheck" type="array" value="T_EXTENDS,T_IMPLEMENTS"/>
	</properties>
</rule>

SlevomatCodingStandard.Namespaces.FullyQualifiedExceptions 🔧

This sniff reduces confusion in the following code snippet:

try {
	$this->foo();
} catch (Exception $e) {
	// Is this the general exception all exceptions must extend from? Or Exception from the current namespace?
}

All references to types named Exception or ending with Exception must be referenced via a fully qualified name:

try {
	$this->foo();
} catch (\FooCurrentNamespace\Exception $e) {

} catch (\Exception $e) {

}

Sniff provides the following settings:

• Exceptions with different names can be configured in specialExceptionNames property.
• If your codebase uses classes that look like exceptions (because they have Exception or Error suffixes) but aren't, you can add them to ignoredNames property and the sniff won't enforce them to be fully qualified. Classes with Error suffix has to be added to ignored only if they are in the root namespace (like LibXMLError).

SlevomatCodingStandard.Namespaces.FullyQualifiedGlobalConstants 🔧

All references to global constants must be referenced via a fully qualified name.

Sniff provides the following settings:

• exclude: list of global constants that are allowed not to be referenced via FQN.

SlevomatCodingStandard.Namespaces.FullyQualifiedGlobalFunctions 🔧

All references to global functions must be referenced via a fully qualified name.

Sniff provides the following settings:

• exclude: list of global functions that are allowed not to be referenced via FQN.

SlevomatCodingStandard.Namespaces.MultipleUsesPerLine

Prohibits multiple uses separated by commas:

use Foo, Bar;

SlevomatCodingStandard.Namespaces.ReferenceUsedNamesOnly 🔧

Sniff provides the following settings:

• searchAnnotations (defaults to false): enables searching for mentions in @var, @param, @return and @throws annotations.
• namespacesRequiredToUse: if not set, all namespaces are required to be used. When set, only mentioned namespaces are required to be used. Useful in tandem with UseOnlyWhitelistedNamespaces sniff.
• fullyQualifiedKeywords: allows fully qualified names after certain keywords. Useful in tandem with FullyQualifiedClassNameAfterKeyword sniff.
• allowFullyQualifiedExceptions, specialExceptionNames & ignoredNames: allows fully qualified exceptions. Useful in tandem with FullyQualifiedExceptions sniff.
• allowFullyQualifiedNameForCollidingClasses: allow fully qualified name for a class with a colliding use statement.
• allowFullyQualifiedNameForCollidingFunctions: allow fully qualified name for a function with a colliding use statement.
• allowFullyQualifiedNameForCollidingConstants: allow fully qualified name for a constant with a colliding use statement.
• allowFullyQualifiedGlobalClasses: allows using fully qualified classes from global space (i.e. \DateTimeImmutable).
• allowFullyQualifiedGlobalFunctions: allows using fully qualified functions from global space (i.e. \phpversion()).
• allowFullyQualifiedGlobalConstants: allows using fully qualified constants from global space (i.e. \PHP_VERSION).
• allowFallbackGlobalFunctions: allows using global functions via fallback name without use (i.e. phpversion()).
• allowFallbackGlobalConstants: allows using global constants via fallback name without use (i.e. PHP_VERSION).
• allowPartialUses: allows using and referencing whole namespaces:

SlevomatCodingStandard.Namespaces.UseOnlyWhitelistedNamespaces

Disallows uses of other than configured namespaces.

Sniff provides the following settings:

• namespacesRequiredToUse: namespaces in this array are the only ones allowed to be used. E. g. root project namespace.
• allowUseFromRootNamespace: also allow using top-level namespace:

use DateTimeImmutable;

SlevomatCodingStandard.Namespaces.UseDoesNotStartWithBackslash 🔧

Disallows leading backslash in use statement:

use \Foo\Bar;

SlevomatCodingStandard.Types.EmptyLinesAroundTypeBraces 🔧

Enforces one configurable number of lines after opening class/interface/trait brace and one empty line before the closing brace.

Sniff provides the following settings:

• linesCountAfterOpeningBrace: allows to configure the number of lines after opening brace.
• linesCountBeforeClosingBrace: allows to configure the number of lines before closing brace.

SlevomatCodingStandard.Namespaces.FullyQualifiedClassNameInAnnotation 🔧

Enforces fully qualified names of classes and interfaces in phpDocs - in @var, @param, @return, @throws. This results in unambiguous phpDocs.

SlevomatCodingStandard.Commenting.ForbiddenAnnotations 🔧

Reports forbidden annotations. No annotations are forbidden by default, the configuration is completely up to the user. It's recommended to forbid obsolete and inappropriate annotations like:

• @author, @created, @version: we have version control systems.
• @package: we have namespaces.
• @copyright, @license: it's not necessary to repeat licensing information in each file.
• @throws: it's not possible to enforce this annotation and the information can become outdated.

Sniff provides the following settings:

• forbiddenAnnotations: allows to configure which annotations are forbidden to be used.

SlevomatCodingStandard.Commenting.ForbiddenComments 🔧

Reports forbidden comments in descriptions. Nothing is forbidden by default, the configuration is completely up to the user. It's recommended to forbid generated or inappropriate messages like:

• Constructor.
• Created by PhpStorm.

Sniff provides the following settings:

• forbiddenCommentPatterns: allows to configure which comments are forbidden to be used. This is an array of regular expressions (PCRE) with delimiters.

SlevomatCodingStandard.Commenting.InlineDocCommentDeclaration 🔧

Reports invalid format of inline phpDocs with @var.

Installation

The recommended way to install Slevomat Coding Standard is through Composer.

{
	"require-dev": {
		"slevomat/coding-standard": "~4.0"
	}
}

It's also recommended to install jakub-onderka/php-parallel-lint which checks source code for syntax errors. Sniffs count on the processed code to be syntactically valid (no parse errors), otherwise they can behave unexpectedly. It is advised to run PHP-Parallel-Lint in your build tool before running PHP_CodeSniffer and exiting the build process early if PHP-Parallel-Lint fails.

How to run the sniffs

You can choose one of two ways to run only selected sniffs from the standard on your codebase:

Choose which sniffs to run

Mention Slevomat Coding Standard in your project's ruleset.xml:

<?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>

When running phpcs on the command line, use the --sniffs option to list all the sniffs you want to use separated by a comma:

vendor/bin/phpcs --standard=ruleset.xml \
--sniffs=SlevomatCodingStandard.ControlStructures.DisallowYodaComparison,SlevomatCodingStandard.Namespaces.AlphabeticallySortedUses \
--extensions=php --encoding=utf-8 --tab-width=4 -sp src tests

Or write your own ruleset.xml by referencing the selected sniffs. This is a sample ruleset.xml:

<?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>

Then run the phpcs executable the usual way:

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

Using all sniffs from the standard

⚠️ This is no longer a recommended way to use Slevomat Coding Standard, because your build can break when moving between minor versions of the standard (which can happen if you use ^ or ~ version constraint in composer.json). We regularly add new sniffs even in minor versions meaning your code won't most likely comply with new minor versions of the package.

If you want to use the whole coding standard, besides requiring slevomat/coding-standard in composer.json, require also Consistence Coding Standard:

{
	"require-dev": {
		"consistence/coding-standard": "~2.0"
	}
}

Then mention both standards in ruleset.xml:

<?xml version="1.0"?>
<ruleset name="AcmeProject">
	<rule ref="vendor/consistence/coding-standard/Consistence/ruleset.xml" />
	<rule ref="vendor/slevomat/coding-standard/SlevomatCodingStandard/ruleset.xml" />
	<!-- additional settings -->
</ruleset>

To check your code base for violations, run PHP-Parallel-Lint and PHP_CodeSniffer from the command line:

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

Fixing errors automatically

Sniffs in this standard marked by the 🔧 symbol support automatic fixing of coding standard violations. To fix your code automatically, run phpcbf instead of phpcs:

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

Always remember to back up your code before performing automatic fixes and check the results with your own eyes as the automatic fixer can sometimes produce unwanted results.

Suppressing sniffs locally

Selected sniffs in this standard marked by the 🚧 symbol can be suppressed for a specific piece of code using an annotation. Consider the following example:

/**
 * @param int $max
 */
public function createProgressBar($max = 0): ProgressBar
{

}

The parameter $max could have a native int scalar typehint. But because the method in the parent class does not have this typehint, so this one cannot have it either. PHP_CodeSniffer shows a following error:

----------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
----------------------------------------------------------------------
 67 | ERROR | [x] Method ErrorsConsoleStyle::createProgressBar()
    |       |     does not have parameter type hint for its parameter $max
    |       |     but it should be possible to add it based on @param
    |       |     annotation "int".
    |       |     (SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingParameterTypeHint)

If we want to suppress this error instead of fixing it, we can take the error code (SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingParameterTypeHint) and use it with a @phpcsSuppress annotation like this:

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

}

Contributing

To make this repository work on your machine, clone it and run these two commands in the root directory of the repository:

composer install
bin/phing

After writing some code and editing or adding unit tests, run phing again to check that everything is OK:

bin/phing

We are always looking forward for your bugreports, feature requests and pull requests. Thank you.

Code of Conduct

This project adheres to a Contributor Code of Conduct. By participating in this project and its community, you are expected to uphold this code.