What’s New in PHP 8.4: Features, Changes, and Deprecations

PHP 8.4 has officially arrived. With the PHP 8.4 release date having occurred on November 21, 2024, PHP teams across the globe are considering when or if they will upgrade. As this release includes several exciting new features and a few key deprecations, teams will need to assess how the changes in PHP 8.4 impact their applications and plans for upgrading or migration.

In this blog, I walk through what you need to know about PHP 8.4 before it releases. I discuss critical dates to keep in mind, explore new features, outline deprecations, and discuss migration considerations for teams building a migration plan.

PHP 8.4 Release Date Overview

PHP 8.4 released on November 21, 2024, making it the first version to release under the new community support life cycle, which changed in June due to an RFC passed earlier this year. 

The new policy starts the release cycle by a month later and reduces the release candidate phase from six to four releases in order to continue hitting the same annual release date. This was done to give more time for feature discussion, and due to a recognition that the additional two release candidates have historically had few, if any, changes.

Additionally, the lifecycle of releases has been extended in two ways. First, instead of hitting end of life (EOL) on an anniversary of the release, the EOL date is now December 31 in all cases. Second, all releases, starting with PHP 8.1, will now receive both two years of active support, including both security and bug fixes, and two years of security-only support, for a total of four years (plus a little over a month).

PHP 8.4 Release Date

The PHP 8.4 release date was November 21, 2024.

PHP 8.4 Release Date Timeline

As discussed above, PHP 8.4 follows a newly condensed timeline compared to previous versions. See the table below for further PHP 8.4 release date details.

New Features (and Deprecations) to Watch in PHP 8.4

Join me for an on-demand webinar, where I take an in-depth look at the new features and key deprecations included in PHP 8.4.

PHP 8.4 Features

PHP 8.4 introduces a number of new features and changes aiming to simplify PHP usage and solve a few common developer challenges. In this section, I will discuss a few of the most prominent PHP 8.4 features:

• Property Hooks
• Asymmetric Visibility
• New Find Array Functions
• MyClass()->method() Without Parentheses
• JIT Changes
• HTML5 Support
• Other PHP 8.4 features to watch

Property Hooks

Properties in PHP objects have raised issues for PHP developers since they were initially provided in the language. Property visibility has helped in many cases, as it allows developers to enforce value validations. The ability to provide property types starting in PHP 7 has helped this even more, but the fact that validation by necessity must happen via a method has led to a lot of boilerplate in the the forms of getters and setters, or abuse of the __get and __set magic methods.

The ability to define readonly properties in PHP 8 solves a lot of problems for many developers as they can guard values via the constructor and still provide fully typed properties for direct access. However, if you want a mutable structure, this only goes so far.

Property Hooks in PHP 8.4 finally provide a robust feature for working with PHP class properties. Properties can now optionally define one or more hooks, currently restricted to "get" and "set", that allow you to hook into the lifecycle of the property. Each hook is a short callable that allows you to perform some logic when the operation is called (e.g., when retrieving a property value, or setting a property value). As a short example from the RFC:

class User implements Named 
{ 
    private bool $isModified = false; 
 
    public function __construct(private string $first, private string $last) {} 
 
    public string $fullName { 
        // Override the "read" action with arbitrary logic. 
        get => $this->first . " " . $this->last; 
 
        // Override the "write" action with arbitrary logic. 
        set {  
            [$this->first, $this->last] = explode(' ', $value, 2); 
            $this->isModified = true; 
        } 
    } 
} 

public private(set) string $bar = 'baz'; 

$request = (new Request())->withMethod('GET')->withUri('/hello-world'); 

$request = new Request()->withMethod('GET')->withUri('/hello-world'); 

function foo(T1 $a, T2 $b = null, T3 $c) {}

function bar(T1 $a, ?T2 $b = null, T3 $c) {} 

function test(T1 $a, T2|null $b = null, T3 $c) {}