Modern PHP 8 features in practice

Property hooks, asymmetric visibility, the pipe operator, clone-with, attributes, and the rewritten DOM and URI extensions.

Property hooks and asymmetric visibility

<?php
declare(strict_types=1);

class User
{
    // asymetric visibility: the world reads the id, only this class writes it
    public private(set) string $id;

    public string $fullName {
        get => $this->first . " " . $this->last;
        set (string $value) {
            [$this->first, $this->last] = explode(" ", $value, 2) + ["", ""];
        }
    }

    public function __construct(string $id, public string $first = "", public string $last = "")
    {
        $this->id = $id;
    }
}

$u = new User("u-1", "Ada", "Lovelace");
echo $u->fullName;
$u->fullName = "Grace Hopper";   // the setter splits it
// $u->id = "x";                 // Error: cannot modify from outside

• A hook turns an ordinary property into a computed one, so callers keep using $obj->name instead of getFullName().
• An asymmetric property has one visibility for reading and another for writing - exactly what identifiers need.
• The backing value is $this->prop inside the hook; a virtual property (a get with no stored value) must not be written without a set hook.

Pipe operator and clone-with

$slug = $title
    |> trim(...)
    |> strtolower(...)
    |> (fn(string $s): string => preg_replace('/[^a-z0-9]+/', '-', $s));

// equivalent without the pipe, read inside out
$slug = preg_replace('/[^a-z0-9]+/', '-', strtolower(trim($title)));

$draft = clone($post, ["status" => Status::Draft, "publishedAt" => null]);

The pipe passes the left-hand value as the argument of the callable on the right, so a chain reads in execution order. clone($object, [ ... ]) produces a modified copy without a temporary variable and without mutating the original.

Attributes and the new DOM and URI extensions

#[\Attribute]
final class Route
{
    public function __construct(public string $path, public string $method = "GET")
    {
    }
}

#[Route("/health")]
function health(): string
{
    return "ok";
}

#[\Deprecated("Use Client::send() instead")]
function send_request(): void
{
}

$ref = new ReflectionFunction("health");
foreach ($ref->getAttributes(Route::class) as $attr) {
    $route = $attr->newInstance();      // the attribute is an object again
    echo $route->method . " " . $route->path;
}

$doc = Dom\HTMLDocument::createFromString("<p>hi</p>");   // 8.4 DOM API
$uri = Uri\Rfc3986\Uri::parse("https://example.com/a?b=1");
echo $uri->getHost();

FAQ

Related

Object-oriented PHP Errors, exceptions and logging

Last refreshed 2026-09-18.