Migration55/new-features-Phpdoc专题

新的特性

新增 Generators

Support for generators has been added via the yield keyword. Generators provide an easy way to implement simple iterators without the overhead or complexity of implementing a class that implements the Iterator interface.

A simple example that reimplements the range function as a generator (at least for positive step values):

<?php
function xrange($start, $limit, $step = 1) {
    for ($i = $start; $i <= $limit; $i += $step) {
        yield $i;
    }
}

echo 'Single digit odd numbers: ';

/* 注意保存在内存中的数组绝不会被创建或返回 */ 
foreach (xrange(1, 9, 2) as $number) {
    echo "$number ";
}
?>

以上例程会输出：

Single digit odd numbers: 1 3 5 7 9

新增 finally 关键字

try-catch blocks now support a finally block for code that should be run regardless of whether an exception has been thrown or not.

foreach 现在支持 list

foreach 控制结构现在支持通过 list 构造将嵌套数组分离到单独的变量。例如：

<?php
$array = [
    [1, 2],
    [3, 4],
];

foreach ($array as list($a, $b)) {
    echo "A: $a; B: $b\n";
}
?>

以上例程会输出：

A: 1; B: 2
A: 3; B: 4

关于 foreach 更深入的文档可参考相关手册页面。

empty 支持任意表达式

empty 现在支持传入一个任意表达式，而不仅是一个变量。例如：

<?php
function always_false() {
    return false;
}

if (empty(always_false())) {
    echo 'This will be printed.';
}

if (empty(true)) {
    echo 'This will not be printed.';
}
?>

以上例程会输出：

This will be printed.

array and string literal dereferencing

Array and string literals can now be dereferenced directly to access individual elements and characters:

<?php
echo 'Array dereferencing: ';
echo [1, 2, 3][0];
echo "\n";

echo 'String dereferencing: ';
echo 'PHP'[0];
echo "\n";
?>

以上例程会输出：

Array dereferencing: 1
String dereferencing: P

新的密码哈希 API

A 新的密码哈希 API that makes it easier to securely hash and manage passwords using the same underlying library as crypt in PHP has been added. See the documentation for password_hash for more detail.

Apache 2.4 handler supported on Windows

The Apache 2.4 handler SAPI is now supported on Windows.

改进 GD

对 GD 扩展做了多方面的改进，包括：

翻转支持使用新的 imageflip 函数。
高级裁剪支持使用 imagecrop & imagecropauto 函数。
WebP 的读写分别支持使用 imagecreatefromwebp & imagewebp 。