New Features in PHP 8.4.1: Property Hooks, Asymmetric Visibility, Deprecation Attributes, Ext‑DOM Enhancements, BCMath Object API, and New array_* Functions

The PHP development team released PHP 8.4.1 on November 21, bringing a collection of security fixes and major language enhancements that target backend developers.

1. Property Hooks allow computed properties to be understood directly by IDEs and static analysis tools, eliminating the need for fragile docblock annotations. They enable reliable pre‑ and post‑processing of values without explicit getters or setters.

countryCode = strtoupper($countryCode);
        }
    }
    public string $combinedCode {
        get => sprintf("%s_%s", $this->languageCode, $this->countryCode);
        set(string $value) {
            [$this->languageCode, $this->countryCode] = explode('_', $value, 2);
        }
    }
    public function __construct(string $languageCode, string $countryCode) {
        $this->languageCode = $languageCode;
        $this->countryCode = $countryCode;
    }
}
$brazilianPortuguese = new Locale('pt', 'br');
var_dump($brazilianPortuguese->countryCode); // BR
var_dump($brazilianPortuguese->combinedCode); // pt_BR
?>

2. Asymmetric Visibility lets developers control the write‑access scope of a property separately from its read‑access scope, reducing the need for verbose getter methods that expose values without permitting external modification.

3. Deprecation Attributes extend PHP’s deprecation mechanism to user‑defined functions, methods, and class constants, providing clearer migration paths.

getVersion();
    }
    public function getVersion(): string { return '8.4'; }
}
$phpVersion = new PhpVersion();
// Deprecated: Method PhpVersion::getPhpVersion() is deprecated since 8.4, use PhpVersion::getVersion() instead
echo $phpVersion->getPhpVersion();
?>

4. New ext‑dom Features and HTML5 Support add a standards‑compliant DOM API, fixing long‑standing spec bugs and providing classes such as Dom\HTMLDocument and Dom\XMLDocument for easier document handling.

PHP 8.4 is a feature‑rich release!
PHP 8.4 adds new DOM classes that are spec‑compliant, keeping the old ones for compatibility.
HTML,
    LIBXML_NOERROR
);
$node = $dom->querySelector('main > article:last-child');
var_dump($node->classList->contains('featured')); // bool(true)
?>

5. BCMath Object API introduces BcMath\Number , an immutable, stringable object that enables object‑oriented arbitrary‑precision arithmetic.

$num2); // false
?>

6. New array_*() Functions add array_find() , array_find_key() , array_any() , and array_all() to simplify common array operations.

str_starts_with($value, 'c')
);
var_dump($animal); // string(3) "cat"
?>

For a complete list of changes, refer to the official release notes at https://www.php.net/releases/8.4/zh.php .