在PHP中为变量添加别名

use MyNamespace\LongClassName as ShortName;

$externalVar = "I am from outside!";

$closure = function() use ($externalVar) {
    echo $externalVar;
};

$closure(); // 输出: I am from outside!

$externalVar = "Hello, world!";

$closure = function() use ($externalVar) {
    echo $externalVar;
};

$closure(); // 正常输出: Hello, world!

// 文件1
use MyNamespace\ClassA as A;

// 文件2
use AnotherNamespace\ClassA as A; // 这里会产生冲突，需要更改别名

<?php
namespace MyNamespace;

class MyClass {
    public function sayHello() {
        echo "Hello from MyClass!";
    }
}

// 使用命名空间别名
use MyNamespace\MyClass as MC;

$mc = new MC();
$mc->sayHello();

// 闭包中使用外部变量
$externalVar = "I am from outside!";

$closure = function() use ($externalVar) {
    echo $externalVar;
};

$closure();
?>