PHP 8 Features Every Developer Should Know

opcache.enable=1
opcache.jit_buffer_size=256M
opcache.jit=1255

#[Attribute(Attribute::TARGET_METHOD | Attribute::TARGET_FUNCTION)]
class Route
{
    public function __construct(
        public string $path,
        public array $methods = ['GET'],
        public ?string $name = null
    ) {}
}

#[Attribute(Attribute::TARGET_PROPERTY)]
class Validate
{
    public function __construct(
        public string $rule,
        public ?string $message = null
    ) {}
}

class UserController
{
    #[Route('/users', methods: ['GET'], name: 'user.list')]
    public function index(): array
    {
        return User::all();
    }

    #[Route('/users/{id}', methods: ['GET', 'POST'])]
    public function show(int $id): User
    {
        return User::findOrFail($id);
    }
}

class User
{
    #[Validate('email', message: 'Invalid email format')]
    public string $email;

    #[Validate('min:8', message: 'Password too short')]
    public string $password;
}

$reflection = new ReflectionClass(UserController::class);

foreach ($reflection->getMethods() as $method) {
    $attributes = $method->getAttributes(Route::class);
    
    foreach ($attributes as $attribute) {
        $route = $attribute->newInstance();
        echo "Path: {$route->path}, Methods: " . implode(',', $route->methods);
    }
}

class Calculator
{
    // Accept int or float, return int or float
    public function add(int|float $a, int|float $b): int|float
    {
        return $a + $b;
    }
}

class Repository
{
    // Return entity or null
    public function find(int $id): User|null
    {
        return User::find($id);
    }

    // Accept multiple input types
    public function search(string|array $criteria): Collection
    {
        if (is_string($criteria)) {
            $criteria = ['name' => $criteria];
        }
        return User::where($criteria)->get();
    }
}

// Properties can have union types too
class ApiResponse
{
    public string|array|null $data = null;
    public int|string $statusCode = 200;
}

// Using expressions in conditions
$result = match(true) {
    $age < 13 => 'Child',
    $age < 20 => 'Teenager',
    $age < 65 => 'Adult',
    default => 'Senior',
};

// With objects and methods
$action = match($request->getMethod()) {
    'GET' => $this->index(),
    'POST' => $this->store($request),
    'PUT', 'PATCH' => $this->update($request),
    'DELETE' => $this->destroy($request),
    default => throw new MethodNotAllowedException(),
};

class CreateUserDTO
{
    public function __construct(
        #[Assert\NotBlank]
        #[Assert\Length(min: 2, max: 50)]
        public readonly string $name,

        #[Assert\Email]
        public readonly string $email,

        #[Assert\PositiveOrZero]
        public readonly int $age = 0,
    ) {}
}

// API response handling
$userName = $response?->data?->user?->name ?? 'Guest';

// Config access
$timeout = $config?->getDatabase()?->getTimeout() ?? 30;

// Collection operations
$firstUserEmail = $users->first()?->email;

// Combined with null coalescing
$avatar = $user?->profile?->avatar ?? '/default-avatar.png';

// In arrow functions
$fn = fn() => throw new Exception('Error!');

// With null coalescing
$value = $array['key'] ?? throw new InvalidArgumentException('Key required');

// In ternary operators
$result = $condition 
    ? $this->process() 
    : throw new LogicException('Condition not met');

// Short-circuit evaluation
$user = $this->findUser($id) ?? throw new UserNotFoundException();

// In match expressions
$message = match($code) {
    200 => 'OK',
    404 => 'Not Found',
    default => throw new UnexpectedValueException("Unknown code: $code"),
};

// PHP 7: Warning, returns null
strlen([]); // Warning: strlen() expects string, array given

// PHP 8: TypeError exception
strlen([]); // TypeError: strlen(): Argument #1 ($string) must be of type string, array given

// New ValueError
array_fill(-1, 5, 'x'); // ValueError: array_fill(): Argument #1 ($start_index) must be >= 0

// Better error messages
function greet(string $name): void {}
greet(123);
// PHP 8: TypeError: greet(): Argument #1 ($name) must be of type string, int given