Manual:Hooks/MessageCacheFetchOverrides

Details
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.

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