PHP - Manual: 新特性

2024-11-14

新特性

PHP 核心中的新特性

属性添加限定类型

类的属性中现在支持添加指定的类型。


<?php
class User {
    public int $id;
    public string $name;
}
?>

上面的例子中，会强制要求 $user->id 只能为 int 类型，同时 $user->name 只能为 string 类型。

箭头函数

箭头函数提供了一种更简洁的定义函数的方法。


<?php
$factor = 10;
$nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]);
// $nums = array(10, 20, 30, 40);
?>

有限返回类型协变与参数类型逆变

以下代码现在可以正常执行：


<?php
class A {}
class B extends A {}

class Producer {
    public function method(): A {}
}
class ChildProducer extends Producer {
    public function method(): B {}
}
?>

只有在使用自动加载的情况下，才会有完整的差异支持。在一个文件内，只有非循环类型引用是可能的，因为在引用之前，所有的类都需要可用。

空合并运算符赋值


<?php
$array['key'] ??= computeDefault();
// 等同于以下旧写法
if (!isset($array['key'])) {
    $array['key'] = computeDefault();
}
?>

数组展开操作


<?php
$parts = ['apple', 'pear'];
$fruits = ['banana', 'orange', ...$parts, 'watermelon'];
// ['banana', 'orange', 'apple', 'pear', 'watermelon'];
?>

数值文字分隔符

数字文字可以在数字之间包含下划线。


<?php
6.674_083e-11; // float
299_792_458;   // decimal
0xCAFE_F00D;   // hexadecimal
0b0101_1111;   // binary
?>

Weak references

Weak references allow the programmer to retain a reference to an object that does not prevent the object from being destroyed.

允许从 __toString() 抛出异常

现在允许从 __toString() 抛出异常。之前的版本，将会导致一个致命错误。新版本中，之前发生致命错误的代码，已经被转换为 Error 异常。

CURL

CURLFile now supports stream wrappers in addition to plain file names, if the extension has been built against libcurl >= 7.56.0.

Filter

The FILTER_VALIDATE_FLOAT filter now supports the min_range and max_range options, with the same semantics as FILTER_VALIDATE_INT.

FFI

FFI is a new extension, which provides a simple way to call native functions, access native variables, and create/access data structures defined in C libraries.

GD

Added the IMG_FILTER_SCATTER image filter to apply a scatter filter to images.

Hash

Added crc32c hash using Castagnoli's polynomial. This CRC32 variant is used by storage systems, such as iSCSI, SCTP, Btrfs and ext4.

Multibyte String

Added the mb_str_split() function, which provides the same functionality as str_split(), but operating on code points rather than bytes.

OPcache

新增缓存预加载特性。

Regular Expressions (Perl-Compatible)

The preg_replace_callback() and preg_replace_callback_array() functions now accept an additional flags argument, with support for the PREG_OFFSET_CAPTURE and PREG_UNMATCHED_AS_NULL flags. This influences the format of the matches array passed to to the callback function.

PDO

The username and password can now be specified as part of the PDO DSN for the mysql, mssql, sybase, dblib, firebird and oci drivers. Previously this was only supported by the pgsql driver. If a username/password is specified both in the constructor and the DSN, the constructor takes precedence.

It is now possible to escape question marks in SQL queries to avoid them being interpreted as parameter placeholders. Writing ?? allows sending a single question mark to the database and e.g. use the PostgreSQL JSON key exists (?) operator.

PDO_OCI

PDOStatement::getColumnMeta() is now available.

PDO_SQLite

PDOStatement::getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT) allows checking whether the statement is read-only, i.e. if it doesn't modify the database.

PDO::setAttribute(PDO::SQLITE_ATTR_EXTENDED_RESULT_CODES, true) enables the use of SQLite3 extended result codes in PDO::errorInfo() and PDOStatement::errorInfo().

SQLite3

Added SQLite3::lastExtendedErrorCode() to fetch the last extended result code.

Added SQLite3::enableExtendedResultCodes($enable = true), which will make SQLite3::lastErrorCode() return extended result codes.

Standard

strip_tags() with array of tag names

strip_tags() now also accepts an array of allowed tags: instead of strip_tags($str, '<a><p>') you can now write strip_tags($str, ['a', 'p']).

Custom object serialization

A new mechanism for custom object serialization has been added, which uses two new magic methods: __serialize and __unserialize.


<?php
// Returns array containing all the necessary state of the object.
public function __serialize(): array;

// Restores the object state from the given data array.
public function __unserialize(array $data): void;
?>

The new serialization mechanism supersedes the Serializable interface, which will be deprecated in the future.

Array merge functions without arguments

array_merge() and array_merge_recursive() may now be called without any arguments, in which case they will return an empty array. This is useful in conjunction with the spread operator, e.g. array_merge(...$arrays).

proc_open() function

proc_open() now accepts an array instead of a string for the command. In this case the process will be opened directly (without going through a shell) and PHP will take care of any necessary argument escaping.


<?php
proc_open(['php', '-r', 'echo "Hello World\n";'], $descriptors, $pipes);
?>

proc_open() now supports redirect and null descriptors.


<?php
// Like 2>&1 on the shell
proc_open($cmd, [1 => ['pipe', 'w'], 2 => ['redirect', 1]], $pipes);
// Like 2>/dev/null or 2>nul on the shell
proc_open($cmd, [1 => ['pipe', 'w'], 2 => ['null']], $pipes);
?>

argon2i(d) without libargon

password_hash() now has the argon2i and argon2id implementations from the sodium extension when PHP is built without libargon.

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User Contributed Notes 2 notes

down

Rain ¶

2 years ago


It should be noted that typed properties internally are never initialized to a default null. Unless of course you initialize them to null yourself. That's why you will always going to encounter this error if you try to access them before initialization.

**Typed property foo::$bar must not be accessed before initialization**

<?php
class User
{
    public $id;
    public string $name; // Typed property (Uninitialized)
    public ?string $age = null; //  Typed property (Initialized)
}

$user = new User;
var_dump(is_null($user->id)); // bool(true)
var_dump(is_null($user->name)); // PHP Fatal error: Typed property User::$name must not be accessed before initialization
var_dump(is_null($user->age));// bool(true)
?>

Another thing worth noting is that it's not possible to initialize a property of type object to anything other than null.  Since the evaluation of properties happens at compile-time and object instantiation happens at runtime. One last thing, callable type is not supported due to its context-dependent behavior.