-#define memcached_success(X) (X) == MEMCACHED_SUCCESS ? true : false
-#define memcached_failed(A) (A) != MEMCACHED_SUCCESS ? true : false
+#define memcached_success(__memcached_return_t) ((__memcached_return_t) == MEMCACHED_SUCCESS or (__memcached_return_t) == MEMCACHED_END)
+#define memcached_failed(__memcached_return_t) ((__memcached_return_t) != MEMCACHED_SUCCESS and (__memcached_return_t) != MEMCACHED_END)
+#define memcached_continue(__memcached_return_t) ((__memcached_return_t) == MEMCACHED_IN_PROGRESS)