What's New in PHP 8.4

PHP 8.4 (released November 2024) is one of the more substantial releases in the PHP 8 series, adding several long-requested language features alongside the usual performance and deprecation work.

Property hooks

Properties can now define get and set behavior directly, without a separate getter/setter method pair:

class User
{
    public string $name {
        set (string $value) {
            $this->name = ucfirst($value);
        }
    }
}

This removes a huge amount of boilerplate in classes that previously needed __get/__set magic methods or explicit accessor methods just to validate or normalize a value on assignment.

Asymmetric visibility

A property can now have a different visibility for reads than for writes — most commonly, publicly readable but only privately writable:

class Order
{
    public private(set) string $status = 'pending';
}

Previously this required a private property plus a public read-only accessor method just to prevent external code from mutating state it shouldn't touch.

New array functions

array_find(), array_any(), and array_all() land in 8.4, closing a long-standing gap versus array_filter() + manual iteration:

$hasAdmin = array_any($users, fn ($user) => $user->isAdmin());

Dom\HTMLDocument

A new Dom\HTMLDocument class provides spec-compliant HTML5 parsing and serialization, addressing long-standing quirks in the legacy DOMDocument class (which predates HTML5 and mishandles many modern HTML documents).

Deprecations to watch for

Implicitly nullable parameter types (e.g. function f(int $x = null) without an explicit ?int) are now deprecated — an explicit ?int is required going forward. Codebases upgrading to 8.4 should expect deprecation notices here and plan to add the explicit ? rather than suppress the warning.