Simple File Based Cache Mechanism in PHP

cache.php

<?php
/**
 * @param string $uniqID - Anything that would be unique to what you are caching (url/database query) 
 * @param integer $expireSeconds - How old is too old that we refresh the cache
 */
function _getFromCache($uniqID,$expireSeconds){
	$uniq = '/<path to your cache storage folder>/'.md5($uniqID);
	if(file_exists($uniq) && time() - filemtime($uniq) <= $expireSeconds){
		return '<process cached file>($uniq)';
	}
	$somethingToCache = '<standard execution to get item>($uniqID)';
	file_put_contents($uniq,$somethingToCache); //You will want to implement __toString() if this is an object or maybe you can just serialize it
	return $somethingToCache;
}