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On 12/08/15 11:08 AM, Ulrich Mueller wrote: |
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>>>>>> On Wed, 12 Aug 2015, Alexis Ballier wrote: |
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> |
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>> i.e. something that really tells the PM how to automate the |
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>> choice: - 'qt5 -> !qt4' is rather straightforward to solve and |
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>> tells the PM how (note that it is not equivalent to 'qt4 -> |
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>> !qt5') - '^^ ( qt5 qt4 )' requires the PM to make a choice in |
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>> order to automate it |
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> |
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> I was thinking about some syntax like this: |
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> |
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> REQUIRED_USE="|| ( +foo bar ) ^^ ( +qt5 -qt4 )" |
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> |
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> The package manager would first evaluate each group in |
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> REQUIRED_USE with the original set of USE flags. If that doesn't |
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> evaluate to true, retry with flags changed as indicated by the + |
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> and - signs. |
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> |
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> Ulrich |
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> |
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Having the ability for REQUIRED_USE to provide a default resolution |
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path should definitely help with things; I assume this is meant to |
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do its work via --autounmask-write or similar, ie to help users |
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adjust their config files? Or was the thought to allow PMs to |
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override USE immediately? |
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Questions: |
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1 - how does +foo in REQUIRED_USE relate to use-defaults set in IUSE? |
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2 - is there a particular reasoning for the - in front of qt4 here? |
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I only ask because it would seem that a single default-enable |
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should suffice in lists like this to indicate a resolution path, no? |
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That is, '^^ ( +flag1 -flag2 -flag3 -flag4 )' to me seems like it |
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would be the same as '^^ ( +flag1 flag2 flag3 flag4 )' |
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3 - will having REQUIRED_USE be able to force flags on (and others |
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off) likely result in abuse of profiles and other use defaults? I |
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forsee this being a way, for instance, for a dev to get around users |
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setting USE="-*" in make.conf to ensure a default use flag setting |
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is honoured. |
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4 - Will a change to which flag the '+' is on likely to require a |
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revbump for VDB updates? For something like '^^ ( +qt4 qt5 )' I |
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could see maintainers wanting to switch which flag is default across |
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a bunch of packages at once when, say, the qt team wants qt5 to |
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become the de-facto default. |
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