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PHP 8.4 New Features

Official Documentation: PHP 8.4 Release

1. Property Hooks​

Property hooks provide support for computed properties that can natively be understood by IDEs and static analysis tools. They allow reliable pre- or post-processing of values, without needing to check whether a matching getter or setter exists in the class.

class User {
    public string $first_name;
    public string $last_name;

    public string $full_name {
        get => "{$this->first_name} {$this->last_name}";
        set (string $value) {
            [$this->first_name, $this->last_name] = explode(' ', $value, 2);
        }
    }
}

2. Asymmetric Visibility​

Properties can now have different visibility for reading and writing.

class User {
    public private(set) string $name;

    public function __construct(string $name) {
        $this->name = $name;
    }
}

$user = new User('John');
echo $user->name; // OK
// $user->name = 'Jane'; // Error: Cannot modify private(set) property

3. New array_*() functions​

New functions array_find(), array_find_key(), array_any(), and array_all() are available.

$animal = array_find(
    ['dog', 'cat', 'cow', 'duck', 'goose'],
    static fn(string $value): bool => str_starts_with($value, 'c'),
);
// $animal is "cat"

4. Instantiating classes without extra parentheses​

Simplified syntax for instantiating classes and calling methods/properties.

// Before PHP 8.4
$name = (new User('John'))->name;

// PHP 8.4
$name = new User('John')->name;

5. #[Deprecated] attribute​

A standard way to mark functions, methods, and class constants as deprecated.

class OldSystem {
    #[Deprecated(since: '1.1', message: 'Use NewSystem::doSomething instead')]
    public function doSomething() {}
}

6. New mb_trim(), mb_ltrim(), and mb_rtrim() functions​

Multibyte versions of the standard trim functions.

7. DateTime::createFromTimestamp()​

A simpler way to create DateTime and DateTimeImmutable objects from a Unix timestamp.

$dt = DateTimeImmutable::createFromTimestamp(1715635200);

8. Bcrypt default cost increase​

Default Bcrypt cost changed from 10 to 12.

9. request_parse_body()​

A new function to parse multipart/form-data and application/x-www-form-urlencoded request bodies manually.

10. exit/die changed from language constructs to functions​

This allows them to be passed to higher-order functions and improves consistency.

11. Implicitly nullable parameter declarations deprecated​

Declaring a parameter with a default value of null without explicitly making it nullable is now deprecated.

// Deprecated in 8.4
function save(string $name = null) {}

// Correct in 8.4
function save(?string $name = null) {}