Php/docs/migration74.new-features
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。
<?phpclass 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]);// $nums = array(10, 20, 30, 40);?>
有限返回类型协变与参数类型逆变
以下代码将不会正常工作：
<?phpclass A {}class B extends A {}class Producer { public function method(): A {}}class ChildProducer extends Producer { public function method(): B {}}?>
只有在使用自动加载的情况下，才会有完整的差异支持。在一个文件内，只有非循环类型引用是可能的，因为在引用之前，所有的类都需要可用。
空合并运算符赋值
<?php$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。
<?php6.674_083e-11; // float299_792_458; // decimal0xCAFE_F00D; // hexadecimal0b0101_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.
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.
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_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
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.
<?phpproc_open(['php', '-r', 'echo "Hello World\n";'], $descriptors, $pipes);?>
proc_open() now supports
redirect and null descriptors.
<?php// Like 2>&1 on the shellproc_open($cmd, [1 => ['pipe', 'w'], 2 => ['redirect', 1]], $pipes);// Like 2>/dev/null or 2>nul on the shellproc_open($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.
