带有匿名函数和闭包的cURL WRITEFUNCTION回调

Question

我正在使用CURLOPT_WRITEFUNCTION的 cURL选项指定一个回调来处理来自cURL请求的数据.

$serverid=5;
$ch=curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://www.whatever.com');
curl_setopt(
    $ch, 
    CURLOPT_WRITEFUNCTION, 
    function ($ch, $string) { 
        return readCallback($ch, $string, $serverid);
    }
);
curl_exec($ch);

function readCallback($ch, $string, $serverid) {
    echo "Server #", $serverid, "  |  ", $string;
    return strlen($string);
}

我想使用匿名函数调用我自己的函数,其中actuall确实work(readCallback()),以便我可以包含与request($serverid)相关联的服务器ID .如何正确利用闭包,以便当cURL命中我的回调匿名函数时,匿名函数知道它最初定义为$serverid=5并且可以readCallback()适当调用？

我最终将使用ParalellCur l和一个常见的回调函数,这就是为什么有一个匿名函数需要使用ID调用我的回调.

Answer 1

如果您希望在匿名函数中访问$ serverid,则必须告诉PHP您要使用该变量.像这样:

/*
 * I replaced the simple $serverid var to $serverIdHolder because
 * 'use' passes the variable by value, so it won't change inside
 * your anonymous function that way. But if you pass a reference
 * to an object, then you are able to see always the current needed value.
 */
$serverIdHolder = new stdClass;
$serverIdHolder->id = 5;

$ch=curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://www.whatever.com');
curl_setopt(
    $ch, 
    CURLOPT_WRITEFUNCTION, 
    function ($ch, $string) use ($serverIdHolder) { 
        return readCallback($ch, $string, $serverIdHolder->id);
    }
);
curl_exec($ch);

function readCallback($ch, $string, $serverid) {
    echo "Server #", $serverid, "  |  ", $string;
    return strlen($string);
}