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On 12/08/15 01:00 PM, Alexis Ballier wrote:
> On Wed, 12 Aug 2015 12:57:25 -0400 Ian Stakenvicius
> <a...@gentoo.org> wrote:
> 
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>> 
>> On 12/08/15 12:42 PM, Ulrich Mueller wrote:
>>> On Wed, 12 Aug 2015, Ian Stakenvicius wrote:
>>>> 2 - is there a particular reasoning for the - in front of
>>>> qt4 here? I only ask because it would seem that a single 
>>>> default-enable should suffice in lists like this to
>>>> indicate a resolution path, no? That is, '^^ ( +flag1
>>>> -flag2 -flag3 -flag4 )' to me seems like it would be the
>>>> same as '^^ ( +flag1 flag2 flag3 flag4 )'
>>> 
>>> If the user has both "qt4 qt5", then enabling qt5 alone
>>> won't help to resolve "^^ ( qt5 qt4 )".
>>> 
>> 
>> Right, but the PM knows based on a particular REQUIRED_USE
>> operator what it would need to do when a particular flag is set
>> to default. Given '^^' is must-be-one-of, the +flag would be
>> enabled and all the other flags would be disabled, right?
>> 
>> Here's how I'd see it mapping out:
>> 
>> || ( +flag1 flag2 ... ) , PM only forces-on flag1 ^^ ( +flag1
>> flag2 ... ) , PM forces-on flag1, forces-off all others ?? (
>> +flag2 flag2 ... ) , PM forces off all but flag1
>> 
>> I'm not sure if the following make sense though... thoughts?
>> 
>> {,!}flag1? ( +flag2 ) , PM forces-on flag2 {,!}flag1? ( +!flag2
>> ) , PM forces !flag2, meaning forces-off flag2
>> 
>> 
>> I'm just wondering if it's really necessary in terms of syntax
>> to specify the flag-negation that the PM would need to do.
> 
> 
> See my other email: neither + nor - are necessary :)
> 
> 


I'd disagree on that -- technically they aren't necessary, but the
whole reason why these new operators were added in the first place
was so that it's a lot easier for developers to fill in REQUIRED_USE
and get the logic right.  Mapping out a ^^ ( flag1 flag2 flag3 flag4
) into all of its permissible flag-a? ( flagb !flagc !flagd )
variants is a royal pain.  Plus there's
readability/understandability to consider here.



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