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From: Eric Blake <eblake@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	"Peter Maydell" <peter.maydell@linaro.org>,
	"open list:Block layer core" <qemu-block@nongnu.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Jason Wang" <jasowang@redhat.com>,
	qemu-devel@nongnu.org, "Michael Roth" <mdroth@linux.vnet.ibm.com>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	"Amit Shah" <amit.shah@redhat.com>,
	"Luiz Capitulino" <lcapitulino@redhat.com>,
	"Andreas Färber" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [PATCH v11 19/28] qapi: Change munging of CamelCase enum values
Date: Wed, 11 Nov 2015 09:03:23 -0700	[thread overview]
Message-ID: <564366CB.6000804@redhat.com> (raw)
In-Reply-To: <87egfwbnfc.fsf@blackfin.pond.sub.org>

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[hmm, wonder why scripts/get-maintainer.pl didn't loop in Gerd to the
patch itself]

On 11/11/2015 07:50 AM, Markus Armbruster wrote:
> Eric Blake <eblake@redhat.com> writes:
> 
>> When munging enum values, the fact that we were passing the entire
>> prefix + value through camel_to_upper() meant that enum values
>> spelled with CamelCase could be turned into CAMEL_CASE.  However,
>> this provides a potential collision (both OneTwo and One-Two would
>> munge into ONE_TWO).  By changing the generation of enum constants
>> to always be prefix + '_' + c_name(value).upper(), we can avoid
>> any risk of collisions (if we can also ensure no case collisions,
>> in the next patch) without having to think about what the
>> heuristics in camel_to_upper() will actually do to the value.
> 
> This is the good part: the rules for clashes become much simpler.
> 
> Bonus: the implementation for detecting them will be simple, too.
> 
>> Thankfully, only two enums are affected: ErrorClass and InputButton.

Visiting just InputButton in this email.

> 
> By convention (see CODING_STYLE), we use CamelCase for type names, and
> nothing else.
> 
> Only enums violating this naming convention can be affected.  The bad
> part: they exist.
> 
> InputButton has two camels: WheelUp and WheelDown.  The C enumeration
> constants change from INPUT_BUTTON_WHEEL_UP/WHEEL_DOWN to
> INPUT_BUTTON_WHEELUP/WHEELDOWN.  Not exactly an improvement, but one,
> there are just 21 occurences in 11 files, and two, I think we can still
> fix the enumeration to "lower case with dash", as it's only used by
> x-input-send-event.

The InputButton type has existed since 2.0; which is then part of the
'InputBtnEvent' struct, then the 'InputEvent' union, also since 2.0.  I
can't easily tell if it was only used internally at that point, or if we
exposed it through the command line (even if we didn't expose it through
QMP); but I concur with your reading that in QMP it is only used via
'x-input-send-event' (since 2.2, but the x- prefix gives us freedom).
[Oh, and I just spotted a typo; 'InputAxis' has a copy-and-paste doc
typo calling it 'InputButton']

If desired, I can prepare an alternate patch that adds the dash to the
qapi enum definition, to see what we think.

But meanwhile, look at some of the lines in the patch:

> diff --git a/ui/sdl.c b/ui/sdl.c
> index 570cb99..2678611 100644
> --- a/ui/sdl.c
> +++ b/ui/sdl.c
> @@ -469,8 +469,8 @@ static void sdl_send_mouse_event(int dx, int dy, int x, int y, int state)
>          [INPUT_BUTTON_LEFT] = SDL_BUTTON(SDL_BUTTON_LEFT),
>          [INPUT_BUTTON_MIDDLE] = SDL_BUTTON(SDL_BUTTON_MIDDLE),
>          [INPUT_BUTTON_RIGHT] = SDL_BUTTON(SDL_BUTTON_RIGHT),
> -        [INPUT_BUTTON_WHEEL_UP] = SDL_BUTTON(SDL_BUTTON_WHEELUP),
> -        [INPUT_BUTTON_WHEEL_DOWN] = SDL_BUTTON(SDL_BUTTON_WHEELDOWN),
> +        [INPUT_BUTTON_WHEELUP] = SDL_BUTTON(SDL_BUTTON_WHEELUP),
> +        [INPUT_BUTTON_WHEELDOWN] = SDL_BUTTON(SDL_BUTTON_WHEELDOWN),

Since SDL already spells the names without space, it's not the end of
the world if we do likewise.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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  reply	other threads:[~2015-11-11 16:06 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-11  6:51 [Qemu-devel] [PATCH v11 00/28] qapi member collision, alternate layout (post-introspection cleanups, subset D) Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 01/28] qapi: Track simple union tag in object.local_members Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 02/28] qapi-types: Consolidate gen_struct() and gen_union() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 03/28] qapi-types: Simplify gen_struct_field[s] Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 04/28] qapi: Drop obsolete tag value collision assertions Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 05/28] qapi: Simplify QAPISchemaObjectTypeMember.check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 06/28] qapi: Clean up after previous commit Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 07/28] qapi: Fix up commit 7618b91's clash sanity checking change Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 08/28] qapi: Eliminate QAPISchemaObjectType.check() variable members Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 09/28] qapi: Factor out QAPISchemaObjectTypeMember.check_clash() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 10/28] qapi: Simplify QAPISchemaObjectTypeVariants.check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 11/28] qapi: Check for qapi collisions of flat union branches Eric Blake
2015-11-11 13:42   ` Markus Armbruster
2015-11-11 15:49     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 12/28] qapi: Factor out QAPISchemaObjectType.check_clash() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 13/28] qapi: Hoist tag collision check to Variants.check() Eric Blake
2015-11-11 13:56   ` Markus Armbruster
2015-11-11 16:11     ` Eric Blake
2015-11-11 17:03       ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 14/28] qapi: Remove outdated tests related to QMP/branch collisions Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 15/28] qapi: Track owner of each object member Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 16/28] qapi: Detect collisions in C member names Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 17/28] cpu: Convert CpuInfo into flat union Eric Blake
2015-11-11 14:13   ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 18/28] qerror: more error_setg() usage Eric Blake
2015-11-11 13:26   ` Andreas Färber
2015-11-11 14:21   ` Markus Armbruster
2015-11-11 14:23     ` Andreas Färber
2015-11-11 15:51       ` Eric Blake
2015-11-11 16:19     ` Eric Blake
2015-11-11 17:31       ` Markus Armbruster
2015-11-11 17:44         ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 19/28] qapi: Change munging of CamelCase enum values Eric Blake
2015-11-11 13:29   ` Andreas Färber
2015-11-11 14:50   ` Markus Armbruster
2015-11-11 16:03     ` Eric Blake [this message]
2015-11-11 17:11       ` Markus Armbruster
2015-11-12  8:34         ` Gerd Hoffmann
2015-11-12 11:16           ` Markus Armbruster
2015-11-12  8:29       ` Gerd Hoffmann
2015-11-11 16:06     ` Eric Blake
2015-11-13 17:46   ` Eric Blake
2015-11-13 18:13     ` Markus Armbruster
2015-11-13 21:37       ` Eric Blake
2015-11-16 14:30         ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 20/28] qapi: Forbid case-insensitive clashes Eric Blake
2015-11-11 14:53   ` Markus Armbruster
2015-11-13  5:32     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 21/28] qapi: Convert qtype_code into qapi enum type Eric Blake
2015-11-11 16:42   ` Markus Armbruster
2015-11-11 17:03     ` Eric Blake
2015-11-12 13:16       ` Markus Armbruster
2015-11-18  6:27         ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 22/28] qapi: Simplify visiting of alternate types Eric Blake
2015-11-12 14:21   ` Markus Armbruster
2015-11-12 15:54   ` Markus Armbruster
2015-11-13 23:54   ` Eric Blake
2015-11-16 14:31     ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 23/28] qapi: Fix alternates that accept 'number' but not 'int' Eric Blake
2015-11-12 15:01   ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 24/28] qapi: Add positive tests to qapi-schema-test Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 25/28] qapi: Simplify visits of optional fields Eric Blake
2015-11-12 15:11   ` Markus Armbruster
2015-11-12 15:30     ` Eric Blake
2015-11-12 16:20       ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 26/28] qapi: Move duplicate member checks to schema check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 27/28] qapi: Move duplicate enum value " Eric Blake
2015-11-12 15:46   ` Markus Armbruster
2015-11-12 16:08     ` Eric Blake
2015-11-18  6:48     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 28/28] qapi: Detect base class loops Eric Blake
2015-11-12 16:06   ` Markus Armbruster

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