class Example
{
    public private(set) static string $classTitle = 'Example class';
 
    // Implicitly public-read, just like object properties.
    protected(set) static int $counter = 0;
 
    public static function changeName(string $name): void
    {
        // From private scope, so this is allowed.
        self::$classTitle = $name;
    }
}
 
print Example::$classTitle; // Allowed.
 
Example::$classTitle = 'Nope'; // Disallowed.

final class Request
{
    #[Validate(is_string(...))]
    #[Validate(static function (string $locale): bool {
        return preg_match('/^[a-z]{2}$/', $locale);
    })]
    public mixed $locale = 'ru';
}

final readonly class Checks
{
    public const Closure IS_STRING = is_string(...);

    public const Closure IS_LOCALE = static function (string $locale): bool {
        return preg_match('/^[a-z]{2}$/', $locale);
    };
}

final readonly class Worker
{
    public function __construct(
        private Closure $onFinish = static function (): void {}
    ) {}

    // ...
}