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On 07/25/2014 05:23 PM, William Hubbs wrote: |
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> On Fri, Jul 25, 2014 at 03:54:53PM -0400, Ian Stakenvicius wrote: |
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>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 |
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>> |
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>> On 25/07/14 03:51 PM, Pacho Ramos wrote: |
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>>> El vie, 25-07-2014 a las 20:46 +0100, Ciaran McCreesh |
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>>> escribió: |
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>>>> On Fri, 25 Jul 2014 21:44:02 +0200 Luis Ressel |
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>>>> <aranea@×××××.de> wrote: |
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>>>>> Okay, I didn't think of that. I'm not sure if the blocker |
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>>>>> deps or the REQUIRED_USE would be more helpful for Portage, |
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>>>>> but generally I think that the REQUIRED_USE error message |
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>>>>> is quite hard to understand for unexperienced users -- much |
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>>>>> more so than the error generated by a blocker dep. |
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>>>> |
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>>>> ...and the fix for that is to scrap REQUIRED_USE and use |
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>>>> pkg_pretend instead. |
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>>>> |
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>>> |
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>>> Could you give an example to let us see how pkg_pretend could |
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>>> be used to achieve the same as REQUIRED_USE? |
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>>> |
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>>> Thanks |
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>>> |
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>>> |
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>> |
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>> pkg_pretend() { if use heimdal && use mit-krb5; then eerror |
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>> "Please set only one of the use following flags:" eerror |
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>> "heimdal, mit-krb5" die "conflicting use flags set" fi } |
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> |
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> I think this could get complicated really quick though. For |
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> example, if I have an ebuild with three use flags, |
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> flag1/flag2/flag3 with the requirement that one and only one of |
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> them must be set, unless bash has an xor operator I don't know |
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> about, that is going to need a lot of nesting etc to get right. |
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> |
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> William |
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> |
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|
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If you want to say "At most one of the flags 'foo', 'bar', and 'baz' |
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may be selected", then you say it like so (requires EAPI=5): |
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|
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REQUIRED_USE="?? ( foo bar baz )" |
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|
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If you want to say "Exactly one of the flags ...", then you use: |
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|
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REQUIRED_USE="^^ ( foo bar baz )" |
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|
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And, as always, you can say "At least one of the flags ..." with: |
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REQUIRED_USE="|| ( foo bar baz )" |
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|
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While each of these can be written using the "foo? ( !bar )"-type |
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primitives, the messages portage outputs are generally better with |
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'??', '^^', and '||', as you might see something like: |
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|
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" |
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The following REQUIRED_USE flag constraints are unsatisfied: |
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at-most-one-of ( foo bar baz ) |
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" |
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|
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Which is, in my opinion, more readable. |
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|
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- -- |
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Jonathan Callen |
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