Available from version 1.41.0 (Gerrit change 884416)
Allows changing message keys, to customize it before the translation is accessed
Define function:
public static function onMessageCacheFetchOverrides( array &$keys ) { ... }
Attach hook: In extension.json:
	"Hooks": {
		"MessageCacheFetchOverrides": "MediaWiki\\Extension\\MyExtension\\Hooks::onMessageCacheFetchOverrides"
Called from: File(s): cache/MessageCache.php
Interface: MessageCacheFetchOverridesHook.php

For more information about attaching hooks, see Manual:Hooks .
For examples of extensions using this hook, see Category:MessageCacheFetchOverrides extensions.

Details edit

Both the input and output keys must have an initial lowercase character. No spaces can be used in the keys; any spaces must be converted to underscores.

  • &$keys - Array of message keys mapped to their replacement.

Values may be either a string or a callable that returns a string. Callables are provided four arguments: the message key, an instance of MessageCache, a Language object and a boolean indicating if the value should be loaded from the database.

function ( string $key, MessageCache $cache, Language $language, bool $useDB ): string { ... }

To prevent ambiguity between message keys that can also be interpreted as a callable (strtotime, for example), all string values are interpreted as a message key. To use a callable defined as a string, use Closure::fromCallable.

See also edit