Re: Bug 23935 - Proposal: New syntax for constraints

On 12/06/2013 07:27 AM, Jan-Ivar Bruaroey wrote:
> I spoke too soon. Our proposals are not the same. :-( See below.
>
> .: Jan-Ivar :.
>
> On 12/5/13 10:11 AM, Jan-Ivar Bruaroey wrote:
>> On 12/4/13 5:13 AM, Harald Alvestrand wrote:
>>> On 12/03/2013 10:47 PM, Jan-Ivar Bruaroey wrote:
>>>> If expressiveness is a problem, we should address this directly,
>>>> which is what I believe my syntax proposal does. I can say:
>>>>
>>>> [ { width: 4096, height: 2160 },
>>>>   { width: 3840, height: 2160 },
>>>>   { width: 2880, height: 1800 },
>>>>   { width: { min: 1024, max: 4096 }, height: { min: 768, max: 2160
>>>> }, aspect: { min: 1.6, max: 1.9 } ]
>>>>
>>>> In this example, I prefer certain resolutions I have tested with
>>>> (even when higher ones are available), and only if I cannot get one
>>>> of those exact ones will I accept a range, but no less than
>>>> 1024x768. How would you express that today?
>>>
>>> Actually, this is ALMOST legal current syntax.
>>>
>>> { optional: [ { width: 4096, height: 2160 },
>>>   { width: 3840, height: 2160 },
>>>   { width: 2880, height: 1800 },
>>>   { width: { min: 1024, max: 4096 }, height: { min: 768, max: 2160
>>> }, aspect: { min: 1.6, max: 1.9 } ]
>>> }
>
> Your example looked so much like mine it threw me. But it will NOT do
> what you intended (or at least what was clear in mine), since the
> optional algorithm is to try to satisfy ALL non-overconstraining
> entries. I.e. a camera that supports both 4096x2160 and 2880x1800 will
> get selected, but always set to the lower resolution, because both
> constraints #0 and #2 will be applied to it.

Nope. The camera will be selected, AND its 4096x2160 configuration will
be selected. The 2880x1800 configuration is then impossible - no
configuration can satisfy both at the same time.

There is a difference, but it is not this one: in the classical
constraint model, you can later add "{flash: on}" and it will be
satisfied no matter which constraints were picked earlier - in your
"pick one" model, it has to be a part of every constraint set.

>
> In contrast, mine bails at the first constraint that applies, which I
> think adheres to POLA. So they are truly different.

They are truly different, but not for this example.

>
> Sorry for not catching that sooner.
>
> .: Jan-Ivar :.
>


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