php - 我可以将其他参数传递给内联 usort 函数吗？

Question

考虑以下代码:

$external_variable = TRUE;
usort($array, function($a, $b) {
    // do sorting stuff based on $external_variable
});

如何在 usort 函数中访问和使用 $external_variable？

Answer 1

使用 use 关键字:

$external_variable = TRUE;

usort($array, function($a, $b) use($external_variable) {
    // do sorting stuff based on $external_variable
});

http://php.net/manual/en/functions.anonymous.php

Closures may also inherit variables from the parent scope. Any such variables must be passed to the use language construct. From PHP 7.1, these variables must not include superglobals, $this, or variables with the same name as a parameter.