PHP7.0和7.1 部分新增特性备忘代码分享

$foo = null;
$bar = $foo ?? 123;

// 相当于 $bar = isset($bar) ? $bar : 123

// 在严格模式下，传参类型不匹配会抛出错误

declare(strict_types=1);

function fn(int $a) : int
{
    echo $a;
}

fn(1.2);

var_dump($a <=> $b);

$a = 0;
$b = "abc";

var_dump($a <=> $b);
// 注意，字符串在与数字比较时会被当作 0；

function generator()
{
    yield 1;
    yield 2;
    return "a";
}

$generator = generator();
foreach ($generator as $val) {
    var_dump($val);
}

var_dump($generator->getReturn());

function generator()
{
    yield 1;
    yield 2;
    return "a";
}

$generator = generator();

var_dump($generator->current());
var_dump($generator->next());

var_dump($generator->getReturn()); // 报错

var_dump($generator->current());
var_dump($generator->next());

define('COLORS', ['red', 'blue', 'black']);
echo COLORS[1];  // red

use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};

list($a, $b) = ["a", "b"];

function(?string $name)
{
    var_dump($name);
}

// 传参类型为 string 或 null

function(string $name = "default-name")
{
    var_dump($name);
}

[$a, $b] = ["a", "b"];

try {
    
} catch (OneException | AnotherException $e) {
    
}