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On Mon, Jul 28, 2014 at 12:02 PM, Ian Stakenvicius <axs@g.o> wrote: |
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> On 28/07/14 07:21 AM, Michał Górny wrote: |
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>> Dnia 2014-07-25, o godz. 14:49:44 Ian Stakenvicius <axs@g.o> |
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>> napisał(a): |
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>> |
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>>> Hey all.. So, putting aside for now how much of a mess this |
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>>> would be to implement in the virtuals' ebuilds themselves, what |
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>>> do people think of changing the virtuals so that they contain an |
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>>> entry in IUSE for each provider that can satisfy it? |
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>>> |
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>>> The idea here is that the package satisfying a virtual could be |
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>>> optionally explicitly-chosen through package.use (or USE= in |
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>>> make.conf, perhaps) instead of having an entry in @world, that |
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>>> way if nothing depends on the virtual then it and the provider |
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>>> can be - --depclean'ed from the system. The idea is specifically |
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>>> NOT to have rdeps depend on these flags, that would undermine the |
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>>> whole purpose of the virtual; it would just be for end-users to |
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>>> set if they so chose. |
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>> |
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>> I think I don't get this argument. |
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>> |
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>> If you really want to have a particular provider for the virtual |
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>> for external purposes, it's fully purposeful to put it in @world |
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>> or otherwise in a custom set. In this case, USE flags aren't |
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>> helpful. |
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> |
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> The argument I was trying to make is that USE flags would allow |
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> end-users to accomplish the same thing, while not having an entry in |
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> @world and therefore allowing the package to be --depclean'ed if the |
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> virtual is --depcleaned. |
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> |
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> I personally don't use sets so i've no idea if the exact same thing |
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> could be accomplished in sets; for some reason i don't think so. |
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> |
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> |
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>> |
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>> If you only prefer a particular provider, you can tip portage |
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>> easily to use it without resorting to USE flags. This also allows |
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>> portage to semi-transparently switch to other provider if |
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>> dependencies need it. In this case, USE flags only make this |
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>> auto-switching harder. |
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> |
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> That is the other part of this idea, to make auto-switching harder, |
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> because right now portage likes to auto-switch even when it seems like |
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> it shouldn't. |
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> |
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> I figure this idea would also help with Ciaran's wishlist item of ||() |
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> deps becoming more strictly-controlled and readily deterministic. |
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> |
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> |
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Also, what about the case where multiple providers for the same |
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virtual are installed but the first doesn't satisfy the dependency? |
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Currently, portage only looks at the installed state of the providers, |
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in order, and will use the first installed provider it finds even if |
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it doesn't actually satisfy the dependency (e.g. due to use deps) and |
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the dependency is already satisfied by a different installed provider. |
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Paludis has an elegant solution for this situation (-F/-A), but afaik |
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portage doesn't. Use flags in virtuals would solve this without |
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having to hack around in portage and have it check all possible deps |
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before choosing one. |
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--James |
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