Re: [Qemu-devel] [PATCH 2/2] qapi: deprecate implicit filters

[Christophe de Dinechin <dinechin@redhat.com>]

John Snow writes:
[...]
>
> This might be OK to do right away, though.
>
> I asked Markus this not too long ago; do we want to amend the QAPI
> schema specification to allow commands to return with "Warning" strings,
> or "Deprecated" stings to allow in-band deprecation notices for cases
> like these?
>
> example:
>
> { "return": {},
>   "deprecated": True,
>   "warning": "Omitting filter-node-name parameter is deprecated, it will
> be required in the future"
> }
>
> There's no "error" key, so this should be recognized as success by
> compatible clients, but they'll definitely see the extra information.
>
> Part of my motivation is to facilitate a more aggressive deprecation of
> legacy features by ensuring that we are able to rigorously notify users
> through any means that they need to adjust their scripts.

I like this approach even if there is no consumer today. It does not
hurt, and it is indeed a motivation to develop consumers that care.

I personally find this much easier to swallow than any kind of crash on
deprecation, which already at the BoF seemed like a really big hammer to
kill a fly.

CC'ing Andrea as well, because we discussed recently about how to deal
with error checking in general, and if a new error checking framework is
being put in place, adding deprecation to the thinking could be a good
idea.

--
Cheers,
Christophe de Dinechin (IRC c3d)