Interface ValueStore

A contract for a class which provides simple get/set/clear access to a single string value. Dropbox\ArrayEntryStore provides an implementation of this for storing a value in a single array element.

Example implementation for a Memcache-based backing store:

class MemcacheValueStore implements ValueStore
{
    private $key;
    private $memcache;

    function __construct($memcache, $key)
    {
        $this->memcache = $memcache;
        $this->key = $key;
    }

    function get()
    {
        $value = $this->memcache->get($this->getKey());
        return $value === false ? null : base64_decode($value);
    }

    function set($value)
    {
        $this->memcache->set($this->key, base64_encode($value));
    }

    function clear()
    {
        $this->memcache->delete($this->key);
    }
}