Share variables between functions in PHP without using globals

Question

I have a class for interacting with a memcache server. I have different functions for inserting, deleting and retrieving data. Originally each function made a call to

Answer 1

You should use dependency injection. The singleton pattern and static constructs are considered bad practice because they essentially are globals (and for good reason -- they cement you to using whatever class you instantiate as opposed to some other).

Here is something like what you should do in order to have easy maintenance.

class MemCache {
    protected $memcache;

    public function __construct(){
        $this->memcache = memcache_connect();
    }
}

class Client {
    protected $MemCache;

    public function __construct( MemCache $MemCache ){
        $this->MemCache = $MemCache;
    }

    public function getMemCache(){
        return $this->MemCache;
    }
}

$MemCache = new MemCache();
$Client = new Client($MemCache);
$MemCache1 = $Client->getMemCache();

// $MemCache and $MemCache1 are the same object. 
// memcache_connect() has not been called more than once.