APC cache improvement

- add cache key prefix
 - use success param at fetch

src/Handlebars/Cache/APC.php

@@ -20,7 +20,7 @@ namespace Handlebars\Cache;
 use Handlebars\Cache;
 
 /**
- * A dummy array cache
+ * A APC cache
  *
  * @category  Xamin
  * @package   Handlebars
@@ -34,6 +34,21 @@ use Handlebars\Cache;
 class APC implements Cache
 {
 
+    /**
+     * @var string
+     */
+    private $_prefix;
+
+    /**
+     * Construct the APC cache.
+     *
+     * @param string|null $prefix optional key prefix, defaults to null
+     */
+    public function __construct( $prefix = null )
+    {
+        $this->_prefix = (string)$prefix;
+    }
+
     /**
      * Get cache for $name if exist.
      *
@@ -43,10 +58,11 @@ class APC implements Cache
      */
     public function get($name)
     {
-        if (apc_exists($name)) {
+        $success = null;
-            return apc_fetch($name);
+        $result = apc_fetch($this->_getKey($name), $success);
-        }
+
-        return false;
+        return $success ? $result : false;
+
     }
 
     /**
@@ -59,7 +75,7 @@ class APC implements Cache
      */
     public function set($name, $value)
     {
-        apc_store($name, $value);
+        apc_store($this->_getKey($name), $value);
     }
 
     /**
@@ -71,7 +87,19 @@ class APC implements Cache
      */
     public function remove($name)
     {
-        apc_delete($name);
+        apc_delete($this->_getKey($name));
+    }
+
+    /**
+     * Gets the full cache key for a given cache item's
+     *
+     * @param string $name Name of the cache item
+     *
+     * @return string full cache key of cached item
+     */
+    private function _getKey($name)
+    {
+        return $this->_prefix . ':' . $name;
     }
 
 }