php - 用 & 符号启动 PHP 函数是什么意思？

Question

我正在使用包含以下代码的 Facebook 库:

class FacebookRestClient {
...
    public function &users_hasAppPermission($ext_perm, $uid=null) {
        return $this->call_method('facebook.users.hasAppPermission', 
        array('ext_perm' => $ext_perm, 'uid' => $uid));
    }
...
}

函数定义开头的 & 是什么意思，我该如何使用这样的库(在一个简单的例子中)

Answer 1

函数名前的和号表示函数将返回对变量的引用而不是值。

Returning by reference is useful when you want to use a function to find to which variable a reference should be bound. Do not use return-by-reference to increase performance. The engine will automatically optimize this on its own. Only return references when you have a valid technical reason to do so.

见 Returning References .