Expiry cache extension

AccessedPolicy.php

<?php

class AccessedPolicy implements PolicyInterface {
  public function __construct($access_count) { /*...*/ }
}

ExpireableItemInterface.php

<?php

interface ExpireableItemInterface extends Psr\Cache\CacheItemInterface
{
    public function setExpiryPolicy(PolicyInterface);
}

ExpireablePoolInterface.php

<?php

interface ExpireablePoolInterface extends Psr\Cache\CachePoolInterface
{
  // .. Whatever.
}

Policyinterface.php

<?php

interface PolicyInterface {
 // ... Whatever.
}

widget.php

<?php

/**
 * Caches a widget.
 */
function set_widget(ExpireablePoolInterface $pool, Widget $widget)
{
    $key = 'widget.' . $widget->id();
    $item = $pool->getItem($key);
    
    // Expire this item after 5 reads or 300 seconds (5 minutes), whichever comes first.
    $item->setExpiryPolicy(new AccessedPolicy(5));
    $item->expireAfter(300);
    $item->set($widget);
    $pool->save($item);
}