PHP 8.1 Analysis | A Look at its Features & Updates

PHP 8.1 will be released within a few months, and once again, many peculiarities of PHP 8.1 get me excited! So in this post, I want to share the actual impact of PHP 8.1 on our code that I’ve observed.

Enums

A much-anticipated feature, enums are coming in PHP 8.1. Earlier, we’ve utilized spatie/enum or myclabs/php-enum for enum support, But now PHP 8.1 will come with this exciting feature. In PHP 8.1 we’ll convert this code:

/**
 * @method static self draft()
 * @method static self published()
 * @method static self archived()
 */
class StatusEnum extends Enum
{
}

To this

enum Status {

 	case draft; 
	case published;
 	case archived;
 }

Array unpacking with string keys

This one might look like a little one, but it has annoyed me more than once: Before PHP 8.1 only list arrays could be unpacked. Here’s an example:

$a = [1, 2, 3];
$b = [4, 5, 6];

// This is allowed
$test = [...$a, ...$b];

While arrays with string keys cannot:

$a = ['a' => 1, 'b' => 2, 'c' => 3];
$b = ['d' => 4, 'e' => 5, 'f' => 6];

$test = [...$a, ...$b]; 

// You'd need to use array_merge in this case
$test = array_merge($a, $b); 

And so, one of the great features of PHP 8.1 that will make my life easier, is that arrays with string keys can now be unpacked as well!

$a = ['a' => 1, 'b' => 2, 'c' => 3];
$b = ['d' => 4, 'e' => 5, 'f' => 6];

// :)
$test = [...$a, ...$b]; 

Class properties: initializers and read-only

Another remarkable feature of PHP 8.1 is that now we can set default arguments in function parameters. Once again, this feature is such a quality-of-life improvement. Imagine you’d want to set a default state class for a BlogData object. Before PHP 8.1 you’d have to make it nullable and set it in the constructor:

class BlogData
{
    public function __construct(
       	public string $title,
        public ?BlogState $state = null,
    ) {
        $this->state ??= new Draft();
    }
}

PHP 8.1 provides that new call directly in the function definition. It will be immense:

class BlogData 
{
   public function __construct( 
	public string $title, 
	public BlogState $state = new Draft(),
	     ) {
 	}
 }

Class properties can be marked as readonly, meaning they can only be written once.

class BlogData 
{ 
   public function __construct( 
	public readonly string $title, 
	public readonly BlogState $state = new Draft(),
		) {
	 }
 }

First-class callable syntax

As if that wasn’t adequate, there’s now also the first-class callable syntax, which provides you a neat way of constructing closures from callables.
Before you’d had to write something like this:

$strlen = Closure::fromCallable('strlen');
$callback = Closure::fromCallable([$object, 'method']);

In PHP 8.1, you can do… this:

$strlen = strlen(...); 
$callback = $object->method(...);

There are even more features in PHP 8.1, but these are the ones I’m most passionate about.