What's New in PHP 8.4: Key Features, Updates, and Deprecated Elements

PHP 8.4, released on November 21, 2024, introduces several significant features and changes aimed at enhancing code quality, performance, and developer experience. Here's an overview of the key updates:

1. Property Hooks

Property hooks allow developers to define custom behavior for property access and modification directly within the class, eliminating the need for traditional getters and setters. This feature simplifies class design and enhances maintainability. citeturn0search0

2. Asymmetric Visibility

PHP 8.4 introduces asymmetric visibility, enabling different visibility levels for reading and writing properties. This means a property can be publicly readable but privately writable, offering greater flexibility in property access control. citeturn0search5

3. New Array Functions

Several new array functions have been added to PHP 8.4 to improve array manipulation:

• array_find(): Returns the value of the first element that satisfies a given condition.
• array_find_key(): Returns the key of the first element that satisfies a given condition.
• array_any(): Checks if any element in the array satisfies a given condition.
• array_all(): Checks if all elements in the array satisfy a given condition.

These functions enhance the expressiveness and efficiency of array operations. citeturn0search1

4. Simplified Object Instantiation

PHP 8.4 allows method chaining on object instantiation without the need for additional parentheses. This results in cleaner and more readable code. citeturn0search2

5. HTML5 Support

The DomHTMLDocument class has been introduced to provide native support for parsing and manipulating HTML5 documents, enhancing PHP's capabilities in web development. citeturn0search6

6. Deprecations and Removals

PHP 8.4 deprecates several features to encourage better coding practices and prepare for future versions:

• Implicitly nullable parameter declarations are deprecated.
• The E_STRICT constant is deprecated.
• Calling session_set_save_handler() with more than two arguments is deprecated.
• The #[\Deprecated] attribute is introduced to mark features for deprecation.

Additionally, the Pspell, IMAP, OCI8, and PDO-OCI extensions have been moved from PHP Core to PECL. citeturn0search1

These changes aim to streamline the language and encourage developers to adopt more robust and modern coding practices.

For a comprehensive list of all changes, refer to the official PHP 8.4 release notes. citeturn0search7

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.

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) {}