新增特性如下

枚举

PHP < 8.1

class Status

{

const DRAFT = 'draft';

const PUBLISHED = 'published';

const ARCHIVED = 'archived';

}

function acceptStatus(string $status) {…}

PHP 8.1

enum Status

{

case Draft;

case Published;

case Archived;

}

function acceptStatus(Status $status) {…}

只读属性

PHP < 8.1

class BlogData

{

private Status $status;

public function __construct(Status $status)

{

$this->status = $status;

}

public function getStatus(): Status

{

return $this->status;

}

}

PHP 8.1

class BlogData

{

public readonly Status $status;

public function __construct(Status $status)

{

$this->status = $status;

}

}

一流的 Callable Syntax

PHP < 8.1

$foo = [$this, 'foo'];

$fn = Closure::fromCallable('strlen');

PHP 8.1

$foo = $this->foo(…);

$fn = strlen(…);

初始化器中的新内容

PHP < 8.1

class Service

{

private Logger $logger;

public function __construct(

?Logger $logger = null,

) {

$this->logger = $logger ?? new NullLogger();

}

}

PHP 8.1

class Service

{

private Logger $logger;

public function __construct(

Logger $logger = new NullLogger(),

) {

$this->logger = $logger;

}

}

对象现在可以用作默认参数值、静态变量和全局常量，以及属性参数。

这有效地使使用嵌套属性成为可能。

PHP < 8.1

class User

{

/**

* @Assert\All({

* @Assert\NotNull,

* @Assert\Length(min=5)

* })

*/

public string $name = '';

}

PHP 8.1

class User

{

#[\Assert\All(

new \Assert\NotNull,

new \Assert\Length(min: 6))

]

public string $name = '';

}

纯交集类型

PHP < 8.1

function count_and_iterate(Iterator $value) {

if (!($value instanceof Countable)) {

throw new TypeError('value must be Countable');

}

foreach ($value as $val) {

echo $val;

}

count($value);

}

PHP 8.1

function count_and_iterate(Iterator&Countable $value) {

foreach ($value as $val) {

echo $val;

}

count($value);

}

当一个值需要同时满足多个类型约束时，使用交集类型。

目前无法将交集和联合类型混合在一起，例如A&B|C.

从不返回类型

PHP < 8.1

function redirect(string $uri) {

header('Location: ' . $uri);

exit();

}

function redirectToLoginPage() {

redirect('/login');

echo 'Hello'; // <- dead code

}

PHP 8.1

function redirect(string $uri): never {

header('Location: ' . $uri);

exit();

}

function redirectToLoginPage(): never {

redirect('/login');

echo 'Hello'; // <- dead code detected by static analysis

}

与声明的函数或方法never类型表明它不会返回一个值，要么抛出一个异常，或与通话结束脚本的执行die()，exit()，trigger_error()，或者类似的东西。

最终类常量

PHP < 8.1

class Foo

{

public const XX = “foo”;

}

class Bar extends Foo

{

public const XX = “bar”; // No error

}

PHP 8.1

class Foo

{

final public const XX = “foo”;

}

class Bar extends Foo

{

public const XX = “bar”; // Fatal error

}

可以声明 final 类常量，以便它们不能在子类中被覆盖。

显式八进制数字表示法Doc

PHP < 8.1

016 === 16; // false because `016` is octal for `14` and it's confusing

016 === 14; // true

PHP 8.1

0o16 === 16; // false — not confusing with explicit notation

0o16 === 14; // true

Fibers

PHP < 8.1

$httpClient->request('https://example.com/')

->then(function (Response $response) {

return $response->getBody()->buffer();

})

->then(function (string $responseBody) {

print json_decode($responseBody)['code'];

});

PHP 8.1

$response = $httpClient->request('https://example.com/');

print json_decode($response->getBody()->buffer())['code'];

对字符串键控数组的数组解包支持

PHP < 8.1

$arrayA = ['a' => 1];

$arrayB = ['b' => 2];

$result = array_merge(['a' => 0], $arrayA, $arrayB);

// ['a' => 1, 'b' => 2]

PHP 8.1

$arrayA = ['a' => 1];

$arrayB = ['b' => 2];

$result = ['a' => 0, …$arrayA, …$arrayB];

// ['a' => 1, 'b' => 2]