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Re: [Qemu-block] [PATCH v1 4/6] qapi: add a text output visitor for pret
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-block] [PATCH v1 4/6] qapi: add a text output visitor for pretty printing types |
Date: |
Tue, 7 Jun 2016 17:45:17 +0100 |
User-agent: |
Mutt/1.6.0 (2016-04-01) |
On Tue, Jun 07, 2016 at 10:40:36AM -0600, Eric Blake wrote:
> On 06/07/2016 10:20 AM, Daniel P. Berrange wrote:
> > On Tue, Jun 07, 2016 at 10:09:48AM -0600, Eric Blake wrote:
> >> On 06/07/2016 04:11 AM, Daniel P. Berrange wrote:
> >>> The current approach for pretty-printing QAPI types is to
> >>> convert them to JSON using the QMP output visitor and then
> >>> pretty-print the JSON document. This has an unfixable problem
> >>> that structs get their keys printed out in random order, since
> >>> JSON dicts do not contain any key ordering information.
> >>>
> >>> To address this, introduce a text output visitor that can
> >>> directly pretty print a QAPI type into a string.
> >>>
> >>> Signed-off-by: Daniel P. Berrange <address@hidden>
> >>> ---
> >>> include/qapi/text-output-visitor.h | 73 ++++++++++++
> >>> include/qapi/visitor-impl.h | 5 +-
> >>> include/qapi/visitor.h | 5 +-
> >>> qapi/Makefile.objs | 1 +
> >>> qapi/opts-visitor.c | 5 +-
> >>> qapi/qapi-dealloc-visitor.c | 4 +-
> >>> qapi/qapi-visit-core.c | 9 +-
> >>> qapi/qmp-input-visitor.c | 5 +-
> >>> qapi/qmp-output-visitor.c | 4 +-
> >>> qapi/string-input-visitor.c | 5 +-
> >>> qapi/string-output-visitor.c | 5 +-
> >>
> >> Why can't we enhance the existing string-output-visitor to handle structs?
> >
> > string-output-visitor seems to be doing something very
> > different from this. In particular it only ever seems
> > to output the values, never the field names. So if we
> > did enhance string-output-visitor, we'd basically have
> > to make all of its code conditional to output in one
> > style or the other style, at which point I didn't think
> > it was really buying us anything vs a new visitor.
>
> That is, it was always doing a top-level visit of a scalar or array of
> scalars, and nothing else. It may still be something that can be merged.
> Maybe I should take a rough shot at it, since I have ideas on how to use
> a common handler for name/list index (and do nothing at the top level),
> then the rest of each callback is independent from what name prefix, if
> any, was output. On the other hand, I guess the way intList is handled
> (compacting it into a single list, instead of each element of the list),
> may indeed be a reason to keep it as two visitors.
If you want to have a shot, go ahead. I put this patch at the end of my
series, since it wasn't a blocking issue to resolve the struct field
ordering, just a "nice to have", so no rush.
Regards,
Daniel
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[Qemu-block] [PATCH v1 2/6] block: export LUKS specific data to qemu-img info, Daniel P. Berrange, 2016/06/07
[Qemu-block] [PATCH v1 6/6] block: convert to use qapi_stringify_ImageInfoSpecific, Daniel P. Berrange, 2016/06/07
[Qemu-block] [PATCH v1 5/6] qapi: generate a qapi_stringify_TYPENAME method for all types, Daniel P. Berrange, 2016/06/07
Re: [Qemu-block] [PATCH v1 0/6] Report format specific info for LUKS block driver, Eric Blake, 2016/06/07