Lazy Evaluation

lazy-generator.php

<?php

// User Generator
function getGuideAuthors(int $guideid): Iterator {
  // Guide::getUserids could be a generator too!
  foreach (Guide::getUserids($guideid) as $userid) {
    // Yield full ORM object.
    yield User::get($userid);
  }
}

function notifyUser(int $guideid, Iterator $users): void {
  $guide = Guide::get($guideid);
  if (!$guide->public) {
    // If the guide isn't public, no Users are generated.
    return;
  }
  
  foreach ($users as $user) {
    sendNotification('stuff', $user);
  }
}

$authorGen = getGuideAuthors(13470);
notifyUsers(13470, $authorGen);