使用 send() - 函数将值传递给生成器

生成器是快速编码的，在许多情况下是重型迭代器实现的简单替代。随着快速实现，当生成器应该停止生成或者是否应该生成其他内容时，会有一点缺乏控制。然而，这可以通过使用 send() 函数来实现，使得请求函数能够在每次循环之后将参数发送到生成器。

//Imagining accessing a large amount of data from a server, here is the generator for this:
function generateDataFromServerDemo()
{
    $indexCurrentRun = 0; //In this example in place of data from the server, I just send feedback everytime a loop ran through.

    $timeout = false;
    while (!$timeout)
    {
        $timeout = yield $indexCurrentRun; // Values are passed to caller. The next time the generator is called, it will start at this statement. If send() is used, $timeout will take this value.
        $indexCurrentRun++;
    }

    yield 'X of bytes are missing. </br>';
}

// Start using the generator
$generatorDataFromServer = generateDataFromServerDemo ();
foreach($generatorDataFromServer as $numberOfRuns)
{
    if ($numberOfRuns < 10)
    {
        echo $numberOfRuns . "</br>";
    }
    else
    {
        $generatorDataFromServer->send(true); //sending data to the generator
        echo $generatorDataFromServer->current(); //accessing the latest element (hinting how many bytes are still missing.
    }
}

导致此输出：