Merge pull request #4525 from masterklavi/memcached_instanceof

Use instanceof instead of get_class() in Cache_memcached
diff --git a/system/libraries/Cache/drivers/Cache_memcached.php b/system/libraries/Cache/drivers/Cache_memcached.php
index 56ab5b8..df02ca2 100644
--- a/system/libraries/Cache/drivers/Cache_memcached.php
+++ b/system/libraries/Cache/drivers/Cache_memcached.php
@@ -116,7 +116,7 @@
 			isset($cache_server['port']) OR $cache_server['port'] = $defaults['port'];
 			isset($cache_server['weight']) OR $cache_server['weight'] = $defaults['weight'];
 
-			if (get_class($this->_memcached) === 'Memcache')
+			if ($this->_memcached instanceof Memcache)
 			{
 				// Third parameter is persistance and defaults to TRUE.
 				$this->_memcached->addServer(
@@ -126,7 +126,7 @@
 					$cache_server['weight']
 				);
 			}
-			else
+			elseif ($this->_memcached instanceof Memcached)
 			{
 				$this->_memcached->addServer(
 					$cache_server['hostname'],
@@ -170,11 +170,11 @@
 			$data = array($data, time(), $ttl);
 		}
 
-		if (get_class($this->_memcached) === 'Memcached')
+		if ($this->_memcached instanceof Memcached)
 		{
 			return $this->_memcached->set($id, $data, $ttl);
 		}
-		elseif (get_class($this->_memcached) === 'Memcache')
+		elseif ($this->_memcached instanceof Memcache)
 		{
 			return $this->_memcached->set($id, $data, 0, $ttl);
 		}