PHP Memcached extension OOP instantiation - oop

Question

Background:
I have installed the PHP Memcached extension on my live server.
Despite various efforts, I can't seem to install Memcached within my XAMPP development box, so I am relying on the following code to only instantiate Memcached only on the Live server:
My connect file which is included in every page:
// MySQL connection here
// Memcached
if($_SERVER['HTTP_HOST'] != 'test.mytestserver') {
$memcache = new Memcached();
$memcache->addServer('localhost', 11211);
}
At the moment I am instantiating each method, and I can't help thinking that that there is a better way to acheive my objective and wonder if anyone has any ideas?
My class file:
class instrument_info {
// Mysqli connection
function __construct($link) {
$this->link = $link;
}
function execute_query($query, $server) {
$memcache = new Memcached();
$memcache->addServer('localhost', 11211);
$result = mysqli_query($this->link, $query) or die(mysqli_error($link));
$row = mysqli_fetch_array($result);
if($server == 'live')
$memcache->set($key, $row, 86400);
} // Close function
function check_something() {
$memcache = new Memcached();
$memcache->addServer('localhost', 11211);
$query = "SELECT something from somewhere";
if($_SERVER['HTTP_HOST'] != 'test.mytestserver') { // Live server
$key = md5($query);
$get_result = $memcache->get($key);
if($get_result) {
$row = $memcache->get($key);
} else {
$this->execute_query($query, 'live');
}
} else { // Test Server
$this->execute_query($query, 'prod');
}
} // Close function
} // Close Class

Answer 1

I would suggest that you read up on interface-based programming and dependency injection. Here's some example code that might give you an idea about how you should go about it.
interface CacheInterface {
function set($name, $val, $ttl);
function get($name);
}
class MemCacheImpl implements CacheInterface {
/* todo: implement interface */
}
class OtherCacheImpl implements CacheInterface {
/* todo: implement interface */
}
class InstrumentInfo {
private $cache;
private $link;
function __construct($link, $cache) {
$this->link = $link;
$this->cache = $cache;
}
function someFunc() {
$content = $this->cache->get('some-id');
if( !$content ) {
// collect content somehow
$this->cache->set('some-id', $content, 3600);
}
return $content
}
}
define('IS_PRODUCTION_ENV', $_SERVER['HTTP_HOST'] == 'www.my-real-website.com');
if( IS_PRODUCTION_ENV ) {
$cache = new MemCacheImpl();
} else {
$cache = new OtherCacheImpl();
}
$instrumentInfo = new InstrumentInfo($link, $cache);
BTW. You actually have the same problem when it comes to mysqli_query, your'e making your code dependent on a Mysql database and the mysqli extension. All calls to mysqli_query should also be moved out to its own class, representing the database layer.