why-when-generator-php-blog-gist5.php

<?php
function createLogger($file)): Generator {
    $f = fopen($file, 'a');
    while (true) {
        $line = yield;
        fwrite($f, $line. "\n");
    }
}

$log = createLogger('/path-to-log/file.log');
$log->send("First");
$log->send("Second");
$log->send("Third");