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Cool new

things in PHP

“While I wasn't paying attention,

PHP got quite good” [1]

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What’s already available

added in PHP ≤7.4, or polyfilled by MediaWiki

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yield

public function provideValues(): iterable {

yield 'null' => [ null ];

yield 'empty string' => [ '' ];

foreach ( [ 0, 1, -1 ] as $number ) {

yield "int $number" => [ $number ];

yield "string $number" => [ (string)$number ];

}

/** @dataProvider provideValues */

public function testSomething( $value ): void { /* ... */ }

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yield

generator syntax
returns an iterable object
extremely useful for PHPUnit data providers

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...

public function msg( string $msg, ...$args ): Message {

return wfMessage( $msg, ...$args )

->inLanguage( $this->getTargetLanguage() )

->page( $this->getPage() );

}

$array1 = [ 2, 3, 4 ];

$array2 = [ 0, 1, ...$array1, 5 ];

// [ 0, 1, 2, 3, 4, 5 ]

includes/parser/Parser.php,

as of commit a4da635e8a,

GPL-2.0-or-later

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...

you can mostly forget about func_get_args() and call_user_func() / call_user_func_array()
writing functions that wrap other functions, passing through all their arguments, is much easier now 😌
spreading in arrays is neat too I guess

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array destructuring

[ $causeAction, $causeAgent ] = $this->getCause();

[ , $lag, $index ] = $this->loadBalancer->getMaxLag();

[

'tables' => $tables,

'fields' => $fields,

'joins' => $joins,

] = $revStore->getQueryInfo();

includes/Storage/DerivedPageDataUpdater.php,

includes/api/ApiQuerySiteinfo.php,

as of commit a4da635e8a,

GPL-2.0-or-later

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array destructuring

forget about list(), just like you forgot about array() – both are [] now
we can also destructure associative arrays now

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static types / type declarations

class CreditsAction extends FormlessAction {

/** @var LinkRenderer */

private $linkRenderer;

/** @var UserFactory */

private $userFactory;

/**

* Convert a Message to a MessageValue

* @param Message $m

* @return MessageValue

public function convertMessage( $m ) {

includes/actions/CreditsAction.php (edited),

includes/Message/Converter.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

💩

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static types / type declarations

class CreditsAction extends FormlessAction {

private LinkRenderer $linkRenderer;

private UserFactory $userFactory;

/** Convert a Message to a MessageValue */

public function convertMessage( Message $m ): MessageValue {

includes/actions/CreditsAction.php (edited),

includes/Message/Converter.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

🤩

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static types / type declarations

source

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static types / type declarations

type declarations, unlike PHPdoc comments, get checked at runtime and are guaranteed to be correct

// sometimes I believe compiler ignores all my comments

mostly obsoletes Assert:parameterType( 'MyType', $x, '$x' );
if the doc comment has no information beyond the types, it’s redundant and can be left out altogether

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strict types

<?php // a.php

function f( string $a ) {

var_dump( $a );

}

<?php // b.php

require_once __DIR__ . '/a.php';

f( 1 );

# logs string(1) "1"

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strict types

<?php // a.php

function f( string $a ) {

var_dump( $a );

}

<?php // b.php

declare( strict_types = 1 );

require_once __DIR__ . '/a.php';

f( 1 );

# TypeError: f(): Argument #1 ($a) must be of type string, int given

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strict types

without strict types, PHP attempts to cast arguments to the expected parameter type
if you would rather have an TypeError, declare strict types
note that the strict types declaration affects the caller, not the callee
in other words, at the callee, a type declaration guarantees that the parameter now has the expected type, but it might have been cast to that type depending on the caller’s argument and its strict types declaration

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arrow functions

$messageKeys = array_map( fn( MessageSpecifier $m ) => $m->getKey(), $messages );

$database->method( 'newSelectQueryBuilder' )

->willReturnCallback( fn() => new SelectQueryBuilder( $database ) );

tests/phpunit/includes/api/ApiBaseTest.php,

tests/phpunit/unit/includes/PingbackTest.php,

as of commit a4da635e8a,

GPL-2.0-or-later

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arrow functions

short and sweet 🙂
automatically capture variables from the outer scope – notice that the second example didn’t need use ( $database )!

but if you want to capture by reference, i.e. use ( &$database ), you’ll still need an old-style function expression

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new operators

'cat_pages' => $countByType['page'] ?? 0,

'cat_subcats' => $countByType['subcat'] ?? 0,

'cat_files' => $countByType['file'] ?? 0

// If length is null, calculate and remember it (potentially SLOW!).

// This is for compatibility with old database rows that don't have the field set.

$this->mSize ??= $this->mSlots->computeSize();

return count( $a ) <=> count( $b );

includes/Category.php,

includes/Revision/RevisionStoreRecord.php,

includes/GlobalFunctions.php,

as of commit 5c9674df53,

GPL-2.0-or-later

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new operators

?? and ??= effectively replace isset() (not empty()!) – like isset(), there is no error if anything is unset (e.g. missing array key, undefined variable)
$a ?: $b evaluates to $b if $a is falsy in any way (zero, empty string, etc.), whereas $a ?? $b only evaluates to $b if $a is null
<=> (“spaceship” :3) is useful for making comparator functions – it compares the two operands and evaluates to an integer less than, equal to or greater than 0, respectively

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new functions

public function isKeyGlobal( $key ) {

return str_starts_with( $key, self::GLOBAL_PREFIX );

}

if ( str_ends_with( MW_CONFIG_FILE, '.php' ) ) {

public static function isExternal( $username ) {

return str_contains( $username, '>' );

}

includes/libs/objectcache/BagOStuff.php,

includes/Setup.php,

includes/user/ExternalUserNames.php,

as of commit a4da635e8a,

GPL-2.0-or-later

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new functions

harder-to-read workarounds (strpos(), substr(), whatever) are no longer needed (see the two RFCs for other problems with such workarounds)
technically, these functions are from PHP 8.0, but MediaWiki pulls in symfony/polyfill-php80 – thanks to Symfony for this useful library ♥

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What’s

coming

PHP ≥8.0, coming soon™ to a production near you!

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Union types

public function getWikiId(): string|false;

public function getId( string|false $wikiId = self::LOCAL ): int;

public function createComment(

IDatabase $dbw,

string|Message|CommentStoreComment $comment,

array $data = null

) {

includes/page/PageReference.php (edited)

includes/page/PageIdentity.php (edited),

includes/CommentStore/CommentStoreBase.php (edited)

as of commit c40084e898,

GPL-2.0-or-later

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Union types

we’ve been using them in PHPDoc for a long time
now we can finally make them proper types too, and get a runtime error if the value isn’t one of the expected types
mostly obsoletes Assert:parameterType( 'A|B|C', $x, '$x' );

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never return type

public function dieReadOnly(): never {

$this->fail( 'Unexpected call to selectField' );

throw new LogicException( 'Ooops' ); // Can't happen, make analyzer happy

includes/api/ApiBase.php (edited),

tests/phpunit/includes/Revision/

RevisionRendererTest.php,

as of commit c40084e898,

GPL-2.0-or-later

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never return type

have a guarantee, at the language level, that the method will never ever return normally

if it doesn’t exit or throw an exception, then PHP will throw an error when the end of the method body is reached

lets us get rid of all sorts of throw new LogicException( 'dieError did not throw an exception' );

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Named arguments

self::$extensionJsonCache[$this->extensionJsonPath] = json_decode(

file_get_contents( $this->extensionJsonPath ),

true,

512,

JSON_THROW_ON_ERROR

);

tests/phpunit/integration/includes/

ExtensionJsonTestBase.php,

as of commit c40084e898,

GPL-2.0-or-later

💩

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Named arguments

self::$extensionJsonCache[$this->extensionJsonPath] = json_decode(

file_get_contents( $this->extensionJsonPath ),

associative: true,

flags: JSON_THROW_ON_ERROR

);

🤩

tests/phpunit/integration/includes/

ExtensionJsonTestBase.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

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Named arguments

can make code much more readable
can skip parameters instead of having to specify the default value
caution: are parameter names part of the stable interface? is renaming a parameter a breaking change? to be decided…

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?->

return $this->user === null ? null : $this->user->getName();

return $this->user?->getName();

$revComment = $rev->getComment() === null ? null : $rev->getComment()->text;

$revComment = $rev->getComment()?->text;

includes/session/UserInfo.php,

(edited),

includes/actions/HistoryAction.php,

(edited),

as of commit c40084e898,

GPL-2.0-or-later

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?->

like -> but only if left-hand side is not null
if used in a chain, the rest of the chain is skipped in case of null, i.e. you can chain normal ->s after the first ?-> and they won’t crash

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Attributes

/**

* @return stdClass|array|false

#[\ReturnTypeWillChange]

public function current();

includes/libs/rdbms/database/

resultwrapper/IResultWrapper.php,

as of commit c40084e898,

GPL-2.0-or-later

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Attributes

syntax for adding additional information to classes, methods, etc.
can be retrieved via reflection
backwards-compatible: single-line attributes will simply be parsed as comments by PHP <8
ReturnTypeWillChange lets us acknowledge the upcoming change to the return type of e.g. Iterator::current() in PHP 9, to avoid a deprecation warning in PHP 8, while staying compatible with PHP 7

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Constructor property promotion

class CreditsAction extends FormlessAction {

private LinkRenderer $linkRenderer;

private UserFactory $userFactory;

public function __construct(

Article $article,

IContextSource $context,

LinkRenderer $linkRenderer,

UserFactory $userFactory

) {

parent::__construct( $article, $context );

$this->linkRenderer = $linkRenderer;

$this->userFactory = $userFactory;

}

includes/actions/CreditsAction.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

🤩

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Constructor property promotion

class CreditsAction extends FormlessAction {

public function __construct(

Article $article,

IContextSource $context,

private LinkRenderer $linkRenderer,

private UserFactory $userFactory

) {

parent::__construct( $article, $context );

}

includes/actions/CreditsAction.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

🤯

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Constructor property promotion

declare class properties as constructor parameters
skip the $this->whatever = $whatever assignment in the constructor
might be contentious, we’ll see 😇

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match expressions

switch ( $ext ) {

case 'gif':

return 'image/gif';

case 'png':

return 'image/png';

case 'jpg':

case 'jpeg':

return 'image/jpeg';

}

return 'unknown/unknown';

includes/StreamFile.php,

as of commit c40084e898,

GPL-2.0-or-later

💩

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match expressions

return match ( $ext ) {

'gif' => 'image/gif',

'png' => 'image/png',

'jpg', 'jpeg' => 'image/jpeg',

default => 'unknown/unknown',

};

includes/StreamFile.php (edited),

as of commit c40084e898,

GPL-2.0-or-later

🤩

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match expressions

concise syntax
strict comparison (===) unlike switch’s loose comparison (==)

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enums

// Audience options for accessors

public const FOR_PUBLIC = 1;

public const FOR_THIS_USER = 2;

public const RAW = 3;

public function getUser( $audience = self::FOR_PUBLIC, Authority $performer = null ) {

// Audience options for accessors

public const AUDIENCE_PUBLIC = 1;

public const AUDIENCE_RAW = 2;

includes/Revision/RevisionRecord.php,

includes/user/CentralId/CentralIdLookup.php,

as of commit 973253a7ee,

GPL-2.0-or-later

😱

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enums

enum RevisionAudience {

case ForPublic;

case ForThisUser;

case Raw;

}

enum CentralIdAudience {

case Public;

case Raw;

}

😌

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enums

“fancy objects” flavor of enums, with potential for future extension to “full Algebraic Data Types (ADTs)” flavor later

as opposed to “fancy constants” flavor
see their survey of enums in various languages

“make invalid states unrepresentable” modeling technique
see the Enumerations RFC, it’s well written

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