Using Named Parameters and Match Expressions in PHP 8

PHP 8 introduces named parameters, enabling arguments to be passed by name rather than position, which allows skipping optional parameters and reordering them freely.

Example:

function test($name, $age='18', $sex='男') {
    echo $name . '-------' . $age . '--------' . $sex;
}

test('Landy', age: 20, sex: '女'); // Landy-------20--------女

You can also skip parameters and rely on defaults:

test('Landy', sex: '女'); // Landy-------18--------女

The order of arguments is no longer fixed:

test(age: 30, sex: '女', name: 'tom'); // tom-------30--------女

Named parameters work with static methods as well:

class Person {
    public static function test($name, $age) {
        echo $name . '|' . $age;
    }
}

Person::test(age: 100, name: 'Landy'); // Landy|100

Variadic functions can receive named arguments after the fixed ones:

function test1($arg1, $arg2, ...$args) {
    print_r($args);
}

test1(1, 2, name: 'Landy', age: 11, sex: 2);
/*
Array
(
    [name] => Landy
    [age] => 11
    [sex] => 2
)
*/

The new match expression provides strict type matching:

$a = 8.0;
echo match($a) {
    8.0 => '匹配8.0',
    '8.0' => 'test 8.0',
    default => '没有匹配值',
}; // 匹配8.0

match can also match expressions and multiple values, and requires a trailing semicolon:

function test3() {
    return 8.0;
}
$a = 8.0;
echo match($a) {
    test3() => '匹配函数',
    8.0 => '匹配8.0',
    '8.0' => 'test 8.0',
    9, 10, 11 => '多次匹配',
    default => '没有匹配值',
}; // 匹配函数

Constructor property promotion lets you define class properties directly in the constructor signature:

class Point {
    public function __construct(
        public float $x = 1.0,
        public float $y = 2.0,
        public float $z = 3.0,
    ) {}
}

echo (new Point())->x; // 1