[PATCH 9/9] domain_conf: rewrite variable setting to ternary operator

Martin Kletzander mkletzan at redhat.com
Thu Jul 21 08:44:45 UTC 2022


On Wed, Jul 20, 2022 at 04:28:30PM +0200, Michal Prívozník wrote:
>On 7/20/22 15:40, Peter Krempa wrote:
>> On Wed, Jul 20, 2022 at 15:11:12 +0200, Kristina Hanicova wrote:
>>> Signed-off-by: Kristina Hanicova <khanicov at redhat.com>
>>> ---
>>>  src/conf/domain_conf.c | 8 ++------
>>>  1 file changed, 2 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>>> index e52f39c809..b600bfec31 100644
>>> --- a/src/conf/domain_conf.c
>>> +++ b/src/conf/domain_conf.c
>>> @@ -4206,12 +4206,8 @@ virDomainObjGetOneDefState(virDomainObj *vm,
>>>      if (virDomainObjUpdateModificationImpact(vm, &flags) < 0)
>>>          return NULL;
>>>
>>> -    if (live) {
>>> -        if (flags & VIR_DOMAIN_AFFECT_LIVE)
>>> -            *live = true;
>>> -        else
>>> -            *live = false;
>>> -    }
>>> +    if (live)
>>> +        *live = (flags & VIR_DOMAIN_AFFECT_LIVE) ? true : false;
>>>
>>
>> https://libvirt.org/coding-style.html#conditional-expressions
>>
>> We suggest that new code avoids ternary operators.
>>
>> I'd prefer if this patch is dropped.
>>
>
>And what about:
>
>if (live)
>  *live = !!(flags & VIR_DOMAIN_AFFECT_LIVE);
>
>? I agree that current version of the code is more verbose than it needs
>to be. And while ternary operators might look bad, in fact I've
>suggested them here:
>
>
>https://gitlab.com/MichalPrivoznik/libvirt/-/commit/d2894d9f07ff2dde77bea53bb39dc8d0176eac85#f6109f17d3eb7394abb620a27ec56d76dd5220b0_4892_4878
>
>Is there any better way?
>

I'll jump in as well, since this seems to be a very heated topic.

How about just:

if (live)
     *live = flags & VIR_DOMAIN_AFFECT_LIVE;

??

If you are worried about the value, then be aware that according to C11
[0] and even C99 [1] (could not find reliable source for C89) section
"6.3.1.2 Boolean type", point 1:

     When any scalar value is converted to _Bool, the result is 0 if the
     value compares equal to 0; otherwise, the result is 1.

[0] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
[1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

>Michal
>
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