Re: [PATCH 1/5] xen/common: introduce a new framework for save/restore of 'domain' context

[Jan Beulich <jbeulich@xxxxxxxx>]

On 01.04.2020 14:16, Julien Grall wrote:
> Hi Jan,
> 
> On 01/04/2020 13:07, Jan Beulich wrote:
>> On 01.04.2020 14:00, Julien Grall wrote:
>>> On 27/03/2020 18:50, Paul Durrant wrote:
>>>> +    if ( (exact ?
>>>> +          (dst_len != c->desc.length) : (dst_len < c->desc.length)) ||
>>>
>>> Using ternary in if is really confusing. How about:
>>>
>>> dst_len < c->desc.length || (exact && dst_len != c->desc.length) ||
>>>
>>> I understand that there would be two check for the exact case but I think 
>>> it is better than a ternary.
>>
>> I'm of the opposite opinion, and hence with Paul. While the alternative
>> you suggest is still reasonable because of the special case here, I
>> find it confusing / more difficult to read / follow
>>
>>      if ( (a && b) || (!a && c) )
>>
>> (and I've seen quite a few instances of such over time) instead of
>>
>>      if ( a ? b : c )
> 
> If the ternary was the only condition and in a single line then it would be 
> okay. However, the if is split over 3 lines...
> 
> The more stuff you put in an if, then more chance you are going to 
> misread/make a mistake (you likely know what I am referring about here ;)).
> 
> So if you prefer the ternary, then we should at least write 2 ifs.

Since it's || that would be fine (albeit not preferred) by me. If
it was &&, would be be suggesting two nested if()-s (which
generally in reviews we ask to be avoided)? I see nothing wrong
with e.g.

      if ( (a ? b : c) &&
           (x ? y : z) )

Nevertheless I agree that very large conditionals often are more
difficult to read.

Jan