Re: [gentoo-dev] useflag policies

[Daniel Campbell (zlg)]

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On 08/02/2015 10:33 AM, Andrew Savchenko wrote:
> On Mon, 3 Aug 2015 00:34:51 +0800 Ben de Groot wrote:
>> Recently some team members of the Qt project have adopted these
>> ebuild policies:
>> https://wiki.gentoo.org/wiki/Project:Qt/Policies
>>
>> I have an issue with the policy adopted under "Requires one of
>> two Qt versions". In my opinion, in the case where a package
>> offers a choice between qt4 or qt5, we should express this in
>> explicit useflags
>
> This is what the policy does: "Implement both qt4 and qt5 USE
> flags"
>
>> and a REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the
>> clearest choice.
>
> This will create insane amount of blockers if users have both
> flags in make.conf (and this is a common scenario).
>
>> Other developers state that users are not interested in such
>> implementation details, or that forced choice through
>> REQUIRED_USE is too much of a hassle. This results in current
>> ebuilds such as quassel to not make it clear that qt4 is an
>> option.
>>
>> This goes against the principle of least surprise, as well as
>> against QA recommendations. I would like to hear specifically
>> from QA about how we should proceed, but comments from the wider
>> developer community are also welcome.
>
> As far as I understand this is done to simplify user's experiense:
> usually people set both USE="qt4 qt5" in global make.conf, because
> they want qt in the first place.
>
> This policy will allow to USE both qt versions whichever is
> available preferring newer one. Quite reasonable approach.
> Alternatives (^^() and ??()) will require micromanagement (e.g.
> pagkage.use.conf) for dozens if not hundreds of packages for no
> good reason. If someone still needs to override such policy (e.g.
> to use qt4 when both are available), this can be done by
> per-package configuration.
>
> My idea is that packages should be fully controllable, but choises
> of default behaviour should be done so, that in most cases
> micromanagement will not be necessary.
>
> I like this qt policy and I'm not sure if it violates any current
> rule. But even in such case this rule should be fixed. Moreover,
> this problem is not limited for qt: we have exactly the same issue
> with gtk2 vs gtk3 and probably some other technologies.
>
> Of course in theory it is possible to build package with two sets
> of binaries supporting both qt4 and qt5, but I see little
> practical need for that.
>
> So I propose to add somewhere to devmanual/policies the following
> recommendation: "If package supports several versions of the same
> technology (e.g. qt4 and qt5) and more than one is enabled by USE
> flags, ebuild should prefer the later one (in terms of technology
> generation).".
>
> Best regards, Andrew Savchenko
>
+1
- -- 
Daniel Campbell - Gentoo Developer
OpenPGP Key: 0x1EA055D6 @ hkp://keys.gnupg.net
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