+ :param ptr: pointer to an initialized `memcached_st` struct
+ :param mem_malloc: pointer to a `memcached_malloc_fn` callback
+ :param mem_free: pointer to a `memcached_free_fn` callback
+ :param mem_realloc: pointer to a `memcached_realloc_fn` callback
+ :param mem_calloc: pointer to a `memcached_calloc_fn` callback
+ :param context: pointer to a user supplied context
+ :returns: `memcached_return_t` indicating success
+