• php之usort对二维数组排序，其中用到__invoke，感觉很巧妙

<?php
class Sort
{
    private $key;
    public function __construct(string $key)
    {
        $this->key = $key;
    }
    public function __invoke(array $a, array $b): int
    {
        return $a[$this->key] <=> $b[$this->key];
    }
}
$customers = [
    ['id' => 1, 'first_name' => 'John', 'last_name' => 'Do'],
    ['id' => 3, 'first_name' => 'Alice', 'last_name' => 'Gustav'],
    ['id' => 2, 'first_name' => 'Bob', 'last_name' => 'Filipe']
];
// sort customers by first name
usort($customers, new Sort('first_name'));
print_r($customers);
// sort customers by last name
usort($customers, new Sort('last_name'));
print_r($customers);
?>

• 输出:

Array
(
    [0] => Array
        (
            [id] => 3
            [first_name] => Alice
            [last_name] => Gustav
        )
    [1] => Array
        (
            [id] => 2
            [first_name] => Bob
            [last_name] => Filipe
        )
    [2] => Array
        (
            [id] => 1
            [first_name] => John
            [last_name] => Do
        )
)
Array
(
    [0] => Array
        (
            [id] => 1
            [first_name] => John
            [last_name] => Do
        )
    [1] => Array
        (
            [id] => 2
            [first_name] => Bob
            [last_name] => Filipe
        )
    [2] => Array
        (
            [id] => 3
            [first_name] => Alice
            [last_name] => Gustav
        )
)