Re: [Libguestfs] [libnbd PATCH 2/4] api: Rearrange flags argument to block_status

Patches 1 & 2 are fine, ACK. I have a separate comment about patch 4 coming up. In libguestfs we handle optional args by putting them in a separate list (so instead of { args; ret } we have we have { args; optargs; ret }). This gets translated into a language like Python in the natural way. However for C it's translated into a varargs list with a rather complex system of flags, see: http://libguestfs.org/guestfs.3.html#calls-with-optional-arguments This has the advantage of supporting optional arguments that can be nullable (or non-zero default value for ints) vs. not present. On the other hand this may be overkill for libnbd. If the only optional argument we support we care about is a non-zero int (or say a non-nullable string where NULL = not present) then mixing the optional args into the same list could be fine. Do we have a good idea about what optional arguments apart from non-zero ints we might need in future? Also, does Python really require optional arguments to be last in the list? (OCaml can have them anywhere in the list) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org