php7.4新特性

时间:2020-05-01

类的属性支持类型声明

class User
{
    public int $id;
    public string $name;

    public function __construct(int $id, string $name)
    {
        $this->id = $id;
        $this->name = $name;
    }
}

$user = new User(1, 'wyzda');
var_dump($user);

箭头函数

array_map — 为数组的每个元素应用回调函数

array_map ( callable $callback , array $array1 [, array $... ] ) : array

array_map():返回数组,是为 array1 每个元素应用 callback函数之后的数组。 callback 函数形参的数量和传给 array_map() 数组数量,两者必须一样。

$arr = array_map(fn($i) => $i + 5, [1, 2, 3]);
var_dump($arr);
$j = fn($i) => $i * 10;
var_dump($j(2));

定义返回类型

class A
{
    public function __construct()
    {
        echo 'A<br>';
    }
}

class B
{
    public function __construct()
    {
        echo 'B<br>';
    }
}

class Producer
{
    public function method(): A
    {
        return new A();
    }
}

class ChildProducer
{
    public function method(): B
    {
        return new B();
    }
}
class Test
{
    function t1(): string
    {
        return '111';
    }

}

$t = new Test();
echo $t->t1();

空赋值运算符

$data = [
    'name' => 'wyzda',
    'age' => 23
];

// 如果不存在,则赋值男
$data['sex'] ??= '男';

var_dump($data);

相当于

if (!isset($data['sex'])) {
    $data['sex'] = '男';
}

数组解包

$nums = [1, 2, 3];
$data = [...$nums, 4, 5];

var_dump($data);

... 相当于将数组的每个值取出来赋值

$nums = [1, 2, 3];
$data = [...$nums, 4, 5];

function add(...$nums)
{
    var_dump($nums);
}

add(1, 2, 3);
add(1, 2, 3, 4);
add(...$data);

数字分隔符

var_dump(6.674_083e-11);
var_dump(299_792_458);
var_dump(299,792,458);
var_dump(0xCAFE_F00D);
var_dump(0b0101_1111);

可以用下划线(_)分割数字

弱引用

允许类的__toString()方法抛出异常

class Test
{
    public function __toString()
    {
        throw new Exception('出错啦');
    }
}

$t = new Test();
$t->__toString();

CURLFile支持stream wrappers

还有其它的一些更新,不一一介绍了。

参考链接:https://www.php.net/manual/zh/migration74.php

Typed properties

Class properties now support type declarations.

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

The above example will enforce that $user->id can only be assigned integer values and $user->name can only be assigned string values.

Arrow functions

Arrow functions provide a shorthand syntax for defining functions with implicit by-value scope binding.

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

Limited return type covariance and argument type contravariance

The following code will now work:

<?php
class A {}
class B extends A {}

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

Full variance support is only available if autoloading is used. Inside a single file only non-cyclic type references are possible, because all classes need to be available before they are referenced.

Null coalescing assignment operator

<?php
$array['key'] ??= computeDefault();
// is roughly equivalent to
if (!isset($array['key'])) {
    $array['key'] = computeDefault();
}
?>

Unpacking inside arrays

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

Numeric literal separator

Numeric literals can contain underscores between digits.

<?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.

Allow exceptions from __toString()

Throwing exceptions from __toString() is now permitted. Previously this resulted in a fatal error. Existing recoverable fatal errors in string conversions have been converted to Error exceptions.

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

Support for preloading code has been added.

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.