From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45599) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dW4YO-0004wX-TH for qemu-devel@nongnu.org; Fri, 14 Jul 2017 13:39:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dW4YN-0002iS-U7 for qemu-devel@nongnu.org; Fri, 14 Jul 2017 13:39:00 -0400 References: <87379zhrhn.fsf@dusky.pond.sub.org> From: Eric Blake Message-ID: <1229e9b6-d675-ee15-ce98-6ee85a4f421b@redhat.com> Date: Fri, 14 Jul 2017 12:38:50 -0500 MIME-Version: 1.0 In-Reply-To: <87379zhrhn.fsf@dusky.pond.sub.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="wDa2N0xQMRNsToHlRAgXHqrEwNEXR8HNp" Subject: Re: [Qemu-devel] qapi: Stop abusing "special" values for something entirely different List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster , qemu-devel@nongnu.org Cc: "Daniel P. Berrange" , Kevin Wolf , qemu-block@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --wDa2N0xQMRNsToHlRAgXHqrEwNEXR8HNp From: Eric Blake To: Markus Armbruster , qemu-devel@nongnu.org Cc: "Daniel P. Berrange" , Kevin Wolf , qemu-block@nongnu.org Message-ID: <1229e9b6-d675-ee15-ce98-6ee85a4f421b@redhat.com> Subject: Re: qapi: Stop abusing "special" values for something entirely different References: <87379zhrhn.fsf@dusky.pond.sub.org> In-Reply-To: <87379zhrhn.fsf@dusky.pond.sub.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 07/14/2017 12:12 PM, Markus Armbruster wrote: >=20 > Instead of the last part, I prefer either >=20 > * so we add a *new* value, such as JSON null. I like that idea. >=20 > 1. Stop abusing values the schema accepts, but are invalid to mean "do > something else entirely". >=20 > 2. Add a first class null type to QAPI. >=20 > 3. Turn MigrationParameters members tls-creds and tls-hostname into > alternate of str and null. Deprecate "". >=20 > 4. Add a null member to alternate BlockdefRef. Deprecate "". Back-compat concerns: would we still accept "" in place of null for a release or two? Is it time to figure out how to add deprecation notices/events to QMP? Or would this be a clean break-over point (since introspection exists), where if introspection shows there is an alternate between string and null, then libvirt MUST use null instead of "" to get the desired semantics? >=20 > I got patches for 2., and I intend to work on 3. and 4. >=20 > Since this is "only" about "less than general and ugly", we may decide > to leave things as they are if my patches turn out even uglier. >=20 > Meanwhile, opinions? Not much time left for soft freeze (which kind of echoes the dilemma we had at 2.9). Is this something you are aiming for in 2.10, or will it be all the harder to worry about back-compat (because we'll have two releases rather than one before we introduce the alternate-with-null semantics)? --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --wDa2N0xQMRNsToHlRAgXHqrEwNEXR8HNp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJZaQGqAAoJEKeha0olJ0NqRHEH/R3qNDNGumxGaPosClnxnd48 AlaGerLkzh2Sl3uvQGuHUNwSCv/iGZ05sfubpqebNWHkbFweCLwa9TCzA/SYsyvR u5/axKxLBDq1O6BqUr0qdWemz6d+LfGuof4CdlwsN2QSoLVAh1XxofWK/1LJC6GT /ZxyfnBgp2JqfenXSEjPaDqMuVx6TZZ24vPZ2m31jR9SRPothnAdPkjeLE0pnTge XKWSgftEjdJLPeSiH6acHpKDJ347UxCHZ7HWAZlvVOySMrJdNKnAeUwnfGCVkokh icVYv2Y5gAyYhWg8RTd3tFRrTslx2HvmKuUHcia/+ffuEBvxSQ4iiQEMKFSjkeU= =7QQe -----END PGP SIGNATURE----- --wDa2N0xQMRNsToHlRAgXHqrEwNEXR8HNp--