[gentoo-dev] useflag policies

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Ben de Groot

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Aug 2, 2015, 12:40:03 PM8/2/15
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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 and a REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the clearest choice.

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.

--
Cheers,

Ben | yngwin
Gentoo developer

Michał Górny

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Aug 2, 2015, 1:30:02 PM8/2/15
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Dnia 2015-08-03, o godz. 00:34:51
Ben de Groot <yng...@gentoo.org> napisał(a):
Long story short, this is USE=gtk once again. GNOME team had a
policy that handled the case cleanly and QA outvoted it in favor of
Qt-like policy. Then Qt team figured out their policy was unfriendly,
and 'fixed' it with this ugly hack...

As I see it, this is a major failure of using toolkit-version oriented
flags rather than feature-oriented flags. Possibilities compared:

USE='qt4 qt5' without ^^ is easy to set since it is free of REQUIRED_USE
issues. However, it's ugly: USE='qt4 qt5' may now mean either both
toolkits or one of them. In the latter case, we have two flag
combinations (= two different binary packages) that mean the same.
Additionally, USE='-qt4 -qt5' may mean both none of them or one of
them. If the latter, yet another case of redundant binary package.

USE='qt4 qt5' with ^^/?? is cleaner from user perspective and better
for binary packages. However, it may mean that user will have to
randomly adjust flags per-package. Which may end up sucking even more
with new Qt versions being introduced and package.use being full of
random '-qt4' and stuff.

What would be really clean is USE='qt qt5' (or 'qt qt4'), alike GNOME
team policy. USE=qt would mean 'any version of Qt, if optional', and
qt4/qt5 would be used to switch between Qt4/Qt5. If Qt would be
obligatory, no USE=qt would apply. If only one Qt version would be
supported, no USE=qt4/qt5 would apply. Clean, sane and limited
package.use cruft.

However, as you can see QA has previously outvoted the clean policy for
USE=gtk. I don't see why it would decide otherwise for USE=qt*.

--
Best regards,
Michał Górny

Andrew Savchenko

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Aug 2, 2015, 1:40:03 PM8/2/15
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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

"Paweł Hajdan, Jr."

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Aug 2, 2015, 1:40:03 PM8/2/15
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On 8/2/15 7:27 PM, Michał Górny wrote:
> What would be really clean is USE='qt qt5' (or 'qt qt4'), alike GNOME
> team policy. USE=qt would mean 'any version of Qt, if optional', and
> qt4/qt5 would be used to switch between Qt4/Qt5. If Qt would be
> obligatory, no USE=qt would apply. If only one Qt version would be
> supported, no USE=qt4/qt5 would apply. Clean, sane and limited
> package.use cruft.

+1

> However, as you can see QA has previously outvoted the clean policy for
> USE=gtk. I don't see why it would decide otherwise for USE=qt*.

I wonder what was the reasoning for the QA decision you refer to. Do you
have more details or archive references?

FWIW I think decisions like that can be revisited. Now could be a good
moment for that.

Paweł

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Ulrich Mueller

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Aug 2, 2015, 2:00:02 PM8/2/15
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>>>>> On Mon, 3 Aug 2015, 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 and a REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user
> the clearest choice.

> 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.

The general policy is outlined here:
https://devmanual.gentoo.org/general-concepts/use-flags/index.html#conflicting-use-flags

# Note: In order to avoid forcing users to micro-manage flags too
# much, REQUIRED_USE should be used sparingly. Follow the normal
# policy whenever it is possible to do a build that will presumably
# suit the user's needs.

So I think the Qt team's policy (i.e. *no* REQUIRED_USE, prefer qt5 in
case of conflicting flags) is perfectly fine.

> 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.

Maybe output an ewarn message if both qt[45] flags are set, and
therefore the qt5 default is taken?

Ulrich

Andrew Savchenko

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Aug 2, 2015, 2:30:02 PM8/2/15
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On Sun, 2 Aug 2015 19:27:02 +0200 Michał Górny wrote:
> Long story short, this is USE=gtk once again. GNOME team had a
> policy that handled the case cleanly and QA outvoted it in favor of
> Qt-like policy. Then Qt team figured out their policy was unfriendly,
> and 'fixed' it with this ugly hack...
>
> As I see it, this is a major failure of using toolkit-version oriented
> flags rather than feature-oriented flags. Possibilities compared:
>
> USE='qt4 qt5' without ^^ is easy to set since it is free of REQUIRED_USE
> issues. However, it's ugly: USE='qt4 qt5' may now mean either both
> toolkits or one of them. In the latter case, we have two flag
> combinations (= two different binary packages) that mean the same.
> Additionally, USE='-qt4 -qt5' may mean both none of them or one of
> them. If the latter, yet another case of redundant binary package.
>
> USE='qt4 qt5' with ^^/?? is cleaner from user perspective and better
> for binary packages. However, it may mean that user will have to
> randomly adjust flags per-package. Which may end up sucking even more
> with new Qt versions being introduced and package.use being full of
> random '-qt4' and stuff.
>
> What would be really clean is USE='qt qt5' (or 'qt qt4'), alike GNOME
> team policy. USE=qt would mean 'any version of Qt, if optional', and
> qt4/qt5 would be used to switch between Qt4/Qt5. If Qt would be
> obligatory, no USE=qt would apply. If only one Qt version would be
> supported, no USE=qt4/qt5 would apply. Clean, sane and limited
> package.use cruft.

This is a clean solution for developers and maintainers, but not
for ordinary users — they will confused by "qt qt4 qt5": "what is
'qt', how is it different from 'qt4' and 'qt5'. What you are really
doing is implementing second-level USE flags, while they were
supposed to be linear.

> However, as you can see QA has previously outvoted the clean policy for
> USE=gtk. I don't see why it would decide otherwise for USE=qt*.
>
> --
> Best regards,
> Michał Górny


Best regards,
Andrew Savchenko

Michał Górny

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Aug 2, 2015, 2:40:02 PM8/2/15
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Dnia 2015-08-02, o godz. 21:21:03
Andrew Savchenko <bir...@gentoo.org> napisał(a):
This can be easily fixed via USE flag descriptions. And unlike with
your solution, the descriptions can be globally consistent.

> What you are really
> doing is implementing second-level USE flags, while they were
> supposed to be linear.

Please support such claims with references.

Andrew Savchenko

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Aug 2, 2015, 3:00:02 PM8/2/15
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A reference from your previous e-mail:
> > On Sun, 2 Aug 2015 19:27:02 +0200 Michał Górny wrote:
[...]
> > > What would be really clean is USE='qt qt5' (or 'qt qt4'), alike GNOME
> > > team policy. USE=qt would mean 'any version of Qt, if optional', and
> > > qt4/qt5 would be used to switch between Qt4/Qt5. If Qt would be
> > > obligatory, no USE=qt would apply. If only one Qt version would be
> > > supported, no USE=qt4/qt5 would apply. Clean, sane and limited
> > > package.use cruft.

You're proposing "qt" as a top level USE flag, while "qt4/qt5" will
be in your opinion optional clarifying USE flags. This way we have
second-level hierarchy.

Best regards,
Andrew Savchenko

Rich Freeman

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Aug 2, 2015, 3:20:02 PM8/2/15
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On Sun, Aug 2, 2015 at 2:21 PM, Andrew Savchenko <bir...@gentoo.org> wrote:
>
> This is a clean solution for developers and maintainers, but not
> for ordinary users — they will confused by "qt qt4 qt5": "what is
> 'qt', how is it different from 'qt4' and 'qt5'. What you are really
> doing is implementing second-level USE flags, while they were
> supposed to be linear.

No argument that it isn't intuitive, but setting USE=qt and forgetting
about it certainly seems more user-friendly than setting qt4/qt5 on
individual packages and worrying about which is better where. To some
extent the current qt policy accomplishes this, but it sacrifices
control when users actually do want it.

I'm a bit torn on the issue myself, but just telling users to set
USE=qt and forget about it unless you really care seems pretty simple
to me. The documentation for USE=qt4/qt5 could say "this is an
advanced setting for users who want to prefer the qt4 implementation
over others - set USE=qt if all you care about is qt support."

--
Rich

Michał Górny

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Aug 2, 2015, 3:30:03 PM8/2/15
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Dnia 2015-08-02, o godz. 21:50:25
I meant the claim that USE flags are supposed to be linear.

Davide Pesavento

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Aug 2, 2015, 3:40:02 PM8/2/15
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On Sun, Aug 2, 2015 at 10:27 AM, Michał Górny <mgo...@gentoo.org> wrote:
> Dnia 2015-08-03, o godz. 00:34:51
> Ben de Groot <yng...@gentoo.org> napisał(a):
>
>> 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 and a
>> REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the clearest choice.
>>
>> 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.
>
> Long story short, this is USE=gtk once again. GNOME team had a
> policy that handled the case cleanly and QA outvoted it in favor of
> Qt-like policy. Then Qt team figured out their policy was unfriendly,
> and 'fixed' it with this ugly hack...

Except that it's not a "ugly hack", but it's in fact recommended by
the devmanual (ulm already quoted the relevant text). I'd agree that
it's not ideal either (but so far I haven't seen any ideal solution
being proposed).

> As I see it, this is a major failure of using toolkit-version oriented
> flags rather than feature-oriented flags. Possibilities compared:

I could agree with this. So, back to USE=gui? A USE_EXPAND maybe?

> What would be really clean is USE='qt qt5' (or 'qt qt4'), alike GNOME
> team policy. USE=qt would mean 'any version of Qt, if optional', and
> qt4/qt5 would be used to switch between Qt4/Qt5. If Qt would be
> obligatory, no USE=qt would apply. If only one Qt version would be
> supported, no USE=qt4/qt5 would apply. Clean, sane and limited
> package.use cruft.
>

I could agree in principle. However this would be a major tree-wide
change, and should happen as quickly as possible to avoid creating
even more confusion for users. Plus, who is willing to do all the
work? (hint: I'm not) ...so, I don't think this solution is practical.

Davide Pesavento

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Aug 2, 2015, 3:50:03 PM8/2/15
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On Sun, Aug 2, 2015 at 12:12 PM, Rich Freeman <ri...@gentoo.org> wrote:
> On Sun, Aug 2, 2015 at 2:21 PM, Andrew Savchenko <bir...@gentoo.org> wrote:
>>
>> This is a clean solution for developers and maintainers, but not
>> for ordinary users — they will confused by "qt qt4 qt5": "what is
>> 'qt', how is it different from 'qt4' and 'qt5'. What you are really
>> doing is implementing second-level USE flags, while they were
>> supposed to be linear.
>
> No argument that it isn't intuitive, but setting USE=qt and forgetting
> about it certainly seems more user-friendly than setting qt4/qt5 on
> individual packages and worrying about which is better where. To some
> extent the current qt policy accomplishes this, but it sacrifices
> control when users actually do want it.

No, it does not. You can still control whether you want qt4 or qt5 on
a per-package basis. The difference is that users that don't care
about this level of control are not forced to make a choice for every
package due to REQUIRED_USE conflicts. Unless I'm missing something...

NP-Hardass

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Aug 2, 2015, 5:20:03 PM8/2/15
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^^ has the pleasant side effect of being easier to read, as a user. The user receives a message saying "at-most-one-of" instead of some convoluted other expression that they don't understand.

I am all for the use of ^^ add the default for this reason.

Additionally, ?? has the same effect of being easy to understand as the description in the error message is in plain English.

--
NP-Hardass
--
NP-Hardass

Ciaran McCreesh

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Aug 2, 2015, 5:30:02 PM8/2/15
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On Sun, 02 Aug 2015 17:14:47 -0400
NP-Hardass <NP-Ha...@gentoo.org> wrote:
> ^^ has the pleasant side effect of being easier to read, as a user.
> The user receives a message saying "at-most-one-of" instead of some
> convoluted other expression that they don't understand.
>
> I am all for the use of ^^ add the default for this reason.
>
> Additionally, ?? has the same effect of being easy to understand as
> the description in the error message is in plain English.

If you cared about readability, you'd use pkg_pretend.

--
Ciaran McCreesh
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Patrick Lauer

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Aug 2, 2015, 8:40:02 PM8/2/15
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No.

Patrick Lauer

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Aug 2, 2015, 9:10:02 PM8/2/15
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On Monday 03 August 2015 00:34:51 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 and a
> REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the clearest choice.

Since qt4 and qt5 are both relatively 'heavy' dependencies and quite different
in many ways (including differences in default styles) many users will want to
stick with only one of those.

The gtk 'solution' forced some ugly things like masking gtk+:3, gconf:3, ...
and then selecting packages based on specific -r200 / -r300 revisions. So much
work to avoid regressing into gtk3!

(Which is especially frustrating because *dbus* has wrong dependencies just so
that gtk/gnome apps using dconf can save config ... )
>
> 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.

I find setting USE="qt4 -qt5" a lot more obvious than having USE="qt" (why not
USE="X" ?) which then does different things based on another useflag,
sometimes. Maybe. It's horribly inconsistent and even might change result over
time, which is not very user-friendly.
>
> 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.

I would prefer having qt4 and qt5 useflags independent, and no generic qt
useflag.

Rich Freeman

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Aug 2, 2015, 9:40:02 PM8/2/15
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On Sun, Aug 2, 2015 at 9:03 PM, Patrick Lauer <pat...@gentoo.org> wrote:
> I find setting USE="qt4 -qt5" a lot more obvious than having USE="qt" (why not
> USE="X" ?) which then does different things based on another useflag,
> sometimes. Maybe. It's horribly inconsistent and even might change result over
> time, which is not very user-friendly.

The problem is that this approach breaks down with scenarios which are
likely to be commonplace.

I want to use fooplayer and bargrapher which are two qt-based
applications. fooplayer only supports qt4, and bargrapher only
supports qt5. What USE flags should I set, without restorting to
per-package flags? Then I also install klunkybrowser which supports
both qt4 and qt5 but not at the same time, so how should I manage my
flags for that?

The current qt policy just has each package support only one version
using USE=qt and while it denies user choice for klunkybrowser it is
at least simple. The alternative of "qt means I don't care what
version" is also simple - the klunkybrowser maintainer would pick the
best default and those who care can override it. The approach qt4=qt4
and qt5=qt5 seems simpler on the surface, but it means that users end
up having to set tons of per-package configurations when they don't
actually care which one they use, and it also doesn't necessarily hint
to users which will give them the best experience on each package.

Right now you can get away with just USE="qt4 -qt5" because we don't
have many qt5-only packages in the tree (I actually have one I've been
holding off on introducing due to qt5 not being in the tree until
recently). When that changes the mutually-exclusive flags approach
will be very painful.

--
Rich

Ben de Groot

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Aug 2, 2015, 11:30:03 PM8/2/15
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On 3 August 2015 at 09:37, Rich Freeman <ri...@gentoo.org> wrote:
> On Sun, Aug 2, 2015 at 9:03 PM, Patrick Lauer <pat...@gentoo.org> wrote:
>> I find setting USE="qt4 -qt5" a lot more obvious than having USE="qt" (why not
>> USE="X" ?) which then does different things based on another useflag,
>> sometimes. Maybe. It's horribly inconsistent and even might change result over
>> time, which is not very user-friendly.
>
> The problem is that this approach breaks down with scenarios which are
> likely to be commonplace.
>
> I want to use fooplayer and bargrapher which are two qt-based
> applications. fooplayer only supports qt4, and bargrapher only
> supports qt5. What USE flags should I set, without restorting to
> per-package flags?

These packages would not have useflags, as they only use one toolkit.

> Then I also install klunkybrowser which supports
> both qt4 and qt5 but not at the same time, so how should I manage my
> flags for that?

Set your global default in make.conf as either qt4 or qt5. If you want
to deviate from that for some package, you can set per package use
flags. Easy peasy. Clear and straightforward. Principle of least
surprise.

> The current qt policy just has each package support only one version
> using USE=qt

No, that is not at all the case. We have banned a simple qt useflag
since many years (which is also the QA policy). We have been using
versioned qt3, qt4, qt5 useflags.

> and while it denies user choice for klunkybrowser it is
> at least simple. The alternative of "qt means I don't care what
> version" is also simple

Except many users do care. I don't see the benefit in changing the way
we used to do this.

> The approach qt4=qt4
> and qt5=qt5 seems simpler on the surface, but it means that users end
> up having to set tons of per-package configurations when they don't
> actually care which one they use, and it also doesn't necessarily hint
> to users which will give them the best experience on each package.

If they don't care, they can simply follow the defaults and not set
any qt4 or qt5 useflags in make.conf.

> Right now you can get away with just USE="qt4 -qt5" because we don't
> have many qt5-only packages in the tree

As I said before, this is of no consequence, as there would be no
mutually exclusive qt4 and qt5 useflags anyway for those packages.

The problem only appears with packages that force a choice between qt4
and qt5, and users that have enabled both useflags globally.

Rich Freeman

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Aug 2, 2015, 11:40:03 PM8/2/15
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On Sun, Aug 2, 2015 at 11:24 PM, Ben de Groot <yng...@gentoo.org> wrote:
>> I want to use fooplayer and bargrapher which are two qt-based
>> applications. fooplayer only supports qt4, and bargrapher only
>> supports qt5. What USE flags should I set, without restorting to
>> per-package flags?
>
> These packages would not have useflags, as they only use one toolkit.
>

What if qt support is optional, and I do/don't want it enabled?

--
Rich

Ben de Groot

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Aug 2, 2015, 11:40:03 PM8/2/15
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On 3 August 2015 at 01:33, Andrew Savchenko <bir...@gentoo.org> wrote:
> On Mon, 3 Aug 2015 00:34:51 +0800 Ben de Groot wrote:
> [...]
> 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.

See https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Policies
under 1.4 and 1.5.

QA has spoken out pretty clearly against unversioned gtk or qt
useflags, and in favour of explicit versioned useflags. Dropping the
explicit qt4 useflag in these cases goes against (at least the spirit
of) this.

> [...]
> 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).".

If we adopt this, we should make sure the users understand this
policy, because it hides certain details from the user.

Ben de Groot

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Aug 2, 2015, 11:40:04 PM8/2/15
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Users who don't care, simply follow the defaults as set by the package
maintainer or profile. Users who do care wouldn't mind adding a rule
to their package.use.

Daniel Campbell (zlg)

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Aug 3, 2015, 3:40:02 AM8/3/15
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256
I like this idea. USE=qt for all apps that optionally support or need
it, qt4/qt5 for apps that support both. We can default to qt5 and
users can still choose qt4 if they prefer it.

- --
Daniel Campbell - Gentoo Developer
OpenPGP Key: 0x1EA055D6 @ hkp://keys.gnupg.net
fpr: AE03 9064 AE00 053C 270C 1DE4 6F7A 9091 1EA0 55D6
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Daniel Campbell (zlg)

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Aug 3, 2015, 3:40:02 AM8/3/15
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+1
- --
Daniel Campbell - Gentoo Developer
OpenPGP Key: 0x1EA055D6 @ hkp://keys.gnupg.net
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Michael Palimaka

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Aug 3, 2015, 7:30:03 AM8/3/15
to
On 03/08/15 07:14, NP-Hardass wrote:
> ^^ has the pleasant side effect of being easier to read, as a user. The
> user receives a message saying "at-most-one-of" instead of some
> convoluted other expression that they don't understand.
>
> I am all for the use of ^^ add the default for this reason.

This introduces a usability nightmare for anyone with both qt4 and qt5
in their global USE flags (a common configuration).

James Le Cuirot

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Aug 3, 2015, 7:40:02 AM8/3/15
to
What if we had something like this?

REQUIRED_IUSE="^^qt ( qt5 qt4 )"

Users who don't care would set just qt rather than qt4 or qt5 and this
mechanism would automatically enable whichever one appears first in the
brackets. If qt4 or qt5 (or both) are set then the behaviour would
remain as it is now. Or perhaps some variation on this?

I'm not declaring this to be a great idea, just throwing it out there
for consideration. :)

--
James Le Cuirot (chewi)
Gentoo Linux Developer

Dale

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Aug 3, 2015, 9:10:04 AM8/3/15
to
As a Gentoo user. This is what I have set and what I hope to get
because of the settings. I have both qt4 and qt5 set in make.conf for
my USE flags. I expect qt5 for whatever packages can work with qt5 and
qt4 for whatever isn't ready for qt5 but requires qt. If for some
reason a package isn't quite ready for qt5 and won't function correctly
for me, I can always set that in package.use until it is. My current
entries for this:

media-libs/phonon-vlc qt5
media-video/mkvtoolnix -qt5

I don't have notes on that so not sure what was ran into to require
those. I may comment those out and give them another try.

Point of this post, provide a little user info about expectations and
settings. Y'all sort out the best way forward and let us know if we
need to change something. :-)

Dale

:-) :-)

Alan McKinnon

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Aug 3, 2015, 10:20:03 AM8/3/15
to
Dale and I think alike.

I also have Qt4 and Qt5 installed, and I expect packages that use them
to link to the version that works better (understanding that "better" is
usually the opinion of upstream and the devs). If I decide I care about
which one works better for a given package, then I'm happy to
package.use but mostly I like that file to be as empty as I can get it.

What I don't want is for the machinery to give the impression that I
can't just go with whatever the dev put in the ebuild for the general
case. I also don't want to have to keep going back to use.desc because
it's not obvious what the flag probably does.

--
Alan McKinnon
alan.m...@gmail.com

Maciej Mrozowski

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Aug 3, 2015, 3:10:03 PM8/3/15
to
On Sunday 02 of August 2015 21:37:36 Rich Freeman wrote:
| The approach qt4=qt4
| and qt5=qt5 seems simpler on the surface, but it means that users end
| up having to set tons of per-package configurations when they don't
| actually care which one they use,

I will risk a thesis that if they didn't care, they wouldn't have chosen
Gentoo...

regards
MM

Dale

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Aug 3, 2015, 4:20:03 PM8/3/15
to
You may lose that one if I'm seeing your point correctly. See Alan and
my earlier replies. I have both qt4 and qt5 set and I leave which is
best to use to the devs to control in the ebuild. If for example qt5
does not work well for a package, let the ebuild pick qt4 for that
package. If qt5 works reliably, then build with qt5. If I have a
problem with it, then I can set it in package.use if needed, doesn't
build or function correctly or I want qt5 even if it isn't stable. As
things switch to qt5 more, I don't have to do anything except let the
updates roll out as they become stable and the dev sets that in the
ebuild.

Keep in mind, devs already do a LOT of the selection process.
Otherwise, we could set any and every USE flag and package combination
there is without any restrictions. In other words, we could have USE
flag soup even if it is known that two or more USE flags clash. As it
is, if a dev knows two flags clash, we get a nifty error message and
then we get to figure out how to get it to work right, sometimes
portage's error message is cryptic to say the least.

If I took your point wrong, my apologies.

Lowly user.

Dale

:-) :-)

Rich Freeman

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Aug 3, 2015, 4:30:03 PM8/3/15
to
Obviously there are many reasons people use Gentoo, but here is my
perspective on this.

The value of Gentoo is that it gives you a LOT of power to tweak
individual package configurations, without the requirement to do this
for everything. There are packages that I carefully configure USE
flags for, CFLAGS for, epatch_user, and so on. Heck, some packages I
run in containers where I can carefully control almost all aspects of
their environment. Then on the same host I'll have screen and bash
and a million other packages installed where exact configuration is
not critical, and so I want it to "just work." If I wanted to
micromanage everything I might as well run Linux From Scratch.

Gentoo should be the best of both worlds. We should give users the
power to tweak things, but we shouldn't force them to play with config
files all day long just to have a functional system. If users want to
care we let them care instead of telling them "don't touch" like most
other distros, but if they don't care we still provide reasonable
defaults.

--
Rich

Alan McKinnon

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Aug 3, 2015, 6:30:02 PM8/3/15
to
+1

One of the most powerful aspects of ebuilds is the ability to not have
to control something the user does not want to. I use Gentoo because I
can control what I wish and like Rich the bits I want to control are a
small fraction of the whole.

When a dev says "I will risk a thesis that if they didn't care, they
wouldn't have chosen Gentoo", there is a place for that but it is by no
means the general case. We DO accommodate the control freaks, we let
them USE="-*" and let them keep all the tiny shards.

But the truth is far more subtle than a care-all/care-none scenario.

I say stick with reasonable defaults, and for better or worse, that
includes "use highest version in ACCEPT_KEYWORDS unless user says otherwise"


--
Alan McKinnon
alan.m...@gmail.com

Ben de Groot

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Aug 4, 2015, 12:00:03 AM8/4/15
to
On 4 August 2015 at 04:20, Rich Freeman <ri...@gentoo.org> wrote:
> [...]
> Gentoo should be the best of both worlds. We should give users the
> power to tweak things, but we shouldn't force them to play with config
> files all day long just to have a functional system. If users want to
> care we let them care instead of telling them "don't touch" like most
> other distros, but if they don't care we still provide reasonable
> defaults.

And that is exactly what we do. The kde profile enables qt4, the
plasma profile enables qt5, the other profiles have no qt* useflags
enabled. These are reasonable defaults.

Of course some users will proceed to enable both qt4 and qt5 globally
in their make.conf, but I don't think it is unreasonable to expect
them to then deal with adding exceptions to package.use for those
packages where exactly-one-of is required.

In my opinion, this is the way Gentoo has always worked, and we should
simply recommend users to only set one of the qt* useflags as globally
enabled, if they want to prevent such micro-management. Hiding the qt4
option is in my opinion the wrong solution around people complaining
after they have consciously enabled both flags.

If this is not acceptable (or "absolutely unusable" as one dev put
it), then we need a proper solution, which a) will not hide the qt4
option, and b) will prevent triggering required_use blockage by
choosing qt5 over qt4 in case both are enabled, while c) informing the
user about this. This probably requires new eclass or even EAPI
functionality.

In the meantime, we should stick with the policies adopted at the qt3
to qt4 transition (explicit versioned useflags) and let the user deal
with per-package management if they enable both flags.

Alexandre Rostovtsev

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Aug 4, 2015, 1:20:02 AM8/4/15
to
On Tue, 2015-08-04 at 11:59 +0800, Ben de Groot wrote:
> On 4 August 2015 at 04:20, Rich Freeman <ri...@gentoo.org> wrote:
> > [...]
> > Gentoo should be the best of both worlds. We should give users the
> > power to tweak things, but we shouldn't force them to play with config
> > files all day long just to have a functional system. If users want to
> > care we let them care instead of telling them "don't touch" like most
> > other distros, but if they don't care we still provide reasonable
> > defaults.
>
> And that is exactly what we do. The kde profile enables qt4, the
> plasma profile enables qt5, the other profiles have no qt* useflags
> enabled. These are reasonable defaults.

That is not correct. The desktop profile enables qt4, because it is a
reasonable default (for qt-only packages, USE=-qt4 means "don't build
any gui", but desktop users always expect some kind of a gui by
default, whether it's gtk or qt*.)

The result is that qt4 is enabled in child profiles of desktop - gnome
and kde and plasma. Since plasma enables qt5 and does nothing with qt4,
you have all qt versions enabled there.

And when popular qt5-only, gui-optional packages appear in the tree, we
will need to enable qt5 in desktop profile too.
signature.asc

Duncan

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Aug 4, 2015, 2:10:02 AM8/4/15
to
Ben de Groot posted on Tue, 04 Aug 2015 11:59:40 +0800 as excerpted:

> In my opinion, this is the way Gentoo has always worked, and we should
> simply recommend users to only set one of the qt* useflags as globally
> enabled, if they want to prevent such micro-management. Hiding the qt4
> option is in my opinion the wrong solution around people complaining
> after they have consciously enabled both flags.
>
> If this is not acceptable (or "absolutely unusable" as one dev put it),
> then we need a proper solution, which a) will not hide the qt4 option,
> and b) will prevent triggering required_use blockage by choosing qt5
> over qt4 in case both are enabled, while c) informing the user about
> this. This probably requires new eclass or even EAPI functionality.

What about a solution such as that used by python, USE=qt, for turning on
qt support at all if it's optional, with QT_TARGETS for people to set to
the versions they want if more than one can be enabled at once, and
QT_SINGLE_TARGET for people to set to their preferred if a package can
build against only one at a time, but that one can be chosen?

And of course, just as with python, people can setup an /etc/portage/env/
* file for exceptions, and point as many packages at that file as desired
using package.env.[1]

But this would be dramatically simpler with qt than it is with python,
since there will normally only be two (with a theoretical but unlikely
possibility of three) choices at the same time, and the time between qt
slot upgrades and slot-effective times as well is much /much/ longer than
between python slot upgrades.

Of course it'd require a whole new set of eclasses, but it's not as if
that hasn't been done before.

[1] FWIW, that's the python solution I've been using for awhile, with
PYTHON_SINGLE_TARGET set to 3.3 and then 3.4 in make.conf, with an
/etc/portage/env/python.starget.27 file that does what the name suggests,
and formerly quite a few package entries in /etc/portage/package.env
pointing to it that couldn't handle python3 yet, but now only one, app-
text/asciidoc.

--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman

Ian Stakenvicius

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Aug 4, 2015, 11:00:06 AM8/4/15
to
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On 03/08/15 03:34 AM, Daniel Campbell (zlg) wrote:
> 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).
>

Why exactly do we need to force-off the use flag for the one that
won't be used, anyways? Yes, there are qt4 deps in VDB that likely
won't be necessary, which causes --depclean to not necessarily be able
to make -as clean- a system, but realistically this is pretty minor.
Also, i don't see why end-users are going to care; if they specify
USE="qt4 qt5" then they should expect the package to depend on both
sets of the qt deps.

As for the ambiguity of which one the package will use, I think we can
satisfy that the same way we do slots -- that is, the one with the
larger ${PV} (ie qt5) is the one that will be used when both are
available. Intuitive, simple, and the system "just works".

Are there any cases where things actually break if a package has both
flags enabled? IE, is three a package with IUSE="qt4 qt5" that when
both flags are enabled would build for qt5 only, and happens to be a
dependency atom of something else that needs it to have qt4 support?
That to me is the only case where a REQUIRED_USE needs to be set on a
package.




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Davide Pesavento

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Aug 4, 2015, 3:10:03 PM8/4/15
to
Exactly, +1.

Davide Pesavento

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Aug 4, 2015, 3:20:02 PM8/4/15
to
On Mon, Aug 3, 2015 at 8:59 PM, Ben de Groot <yng...@gentoo.org> wrote:
> On 4 August 2015 at 04:20, Rich Freeman <ri...@gentoo.org> wrote:
>> [...]
>> Gentoo should be the best of both worlds. We should give users the
>> power to tweak things, but we shouldn't force them to play with config
>> files all day long just to have a functional system. If users want to
>> care we let them care instead of telling them "don't touch" like most
>> other distros, but if they don't care we still provide reasonable
>> defaults.
>
> And that is exactly what we do. The kde profile enables qt4, the
> plasma profile enables qt5, the other profiles have no qt* useflags
> enabled. These are reasonable defaults.
>

As tetromino pointed out, this is very far from the real current situation.

> Of course some users will proceed to enable both qt4 and qt5 globally
> in their make.conf, but I don't think it is unreasonable to expect
> them to then deal with adding exceptions to package.use for those
> packages where exactly-one-of is required.
>
> In my opinion, this is the way Gentoo has always worked, and we should
> simply recommend users to only set one of the qt* useflags as globally
> enabled, if they want to prevent such micro-management. Hiding the qt4
> option is in my opinion the wrong solution around people complaining
> after they have consciously enabled both flags.
>
> If this is not acceptable (or "absolutely unusable" as one dev put
> it), then we need a proper solution, which a) will not hide the qt4
> option, and b) will prevent triggering required_use blockage by
> choosing qt5 over qt4 in case both are enabled, while c) informing the
> user about this. This probably requires new eclass or even EAPI
> functionality.
>

Please go ahead and design and implement such functionality (a sort of
REQUIRED_USE defaults). In the meantime, we will apply the policies
written in the Qt project wiki page.

> In the meantime, we should stick with the policies adopted at the qt3
> to qt4 transition (explicit versioned useflags) and let the user deal
> with per-package management if they enable both flags.
>

We didn't have REQUIRED_USE at the time of the qt3->qt4 transition, so
this point is completely moot.

Ben de Groot

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Aug 5, 2015, 2:40:03 AM8/5/15
to
On 4 August 2015 at 22:56, Ian Stakenvicius <a...@gentoo.org> wrote:
> Are there any cases where things actually break if a package has both
> flags enabled? IE, is three a package with IUSE="qt4 qt5" that when
> both flags are enabled would build for qt5 only, and happens to be a
> dependency atom of something else that needs it to have qt4 support?
> That to me is the only case where a REQUIRED_USE needs to be set on a
> package.

I'm not aware we have such a package, but I may be overlooking
something. Either way, I think it is a dangerous road to go down that
way.

Ben de Groot

unread,
Aug 5, 2015, 2:50:02 AM8/5/15
to
On 5 August 2015 at 03:09, Davide Pesavento <pe...@gentoo.org> wrote:
> On Mon, Aug 3, 2015 at 8:59 PM, Ben de Groot <yng...@gentoo.org> wrote:
>> On 4 August 2015 at 04:20, Rich Freeman <ri...@gentoo.org> wrote:
>>> [...]
>>> Gentoo should be the best of both worlds. We should give users the
>>> power to tweak things, but we shouldn't force them to play with config
>>> files all day long just to have a functional system. If users want to
>>> care we let them care instead of telling them "don't touch" like most
>>> other distros, but if they don't care we still provide reasonable
>>> defaults.
>>
>> And that is exactly what we do. The kde profile enables qt4, the
>> plasma profile enables qt5, the other profiles have no qt* useflags
>> enabled. These are reasonable defaults.
>>
>
> As tetromino pointed out, this is very far from the real current situation.

Indeed, I was wrong here. We will need another solution.

>> Of course some users will proceed to enable both qt4 and qt5 globally
>> in their make.conf, but I don't think it is unreasonable to expect
>> them to then deal with adding exceptions to package.use for those
>> packages where exactly-one-of is required.
>>
>> In my opinion, this is the way Gentoo has always worked, and we should
>> simply recommend users to only set one of the qt* useflags as globally
>> enabled, if they want to prevent such micro-management. Hiding the qt4
>> option is in my opinion the wrong solution around people complaining
>> after they have consciously enabled both flags.
>>
>> If this is not acceptable (or "absolutely unusable" as one dev put
>> it), then we need a proper solution, which a) will not hide the qt4
>> option, and b) will prevent triggering required_use blockage by
>> choosing qt5 over qt4 in case both are enabled, while c) informing the
>> user about this. This probably requires new eclass or even EAPI
>> functionality.
>>
>
> Please go ahead and design and implement such functionality (a sort of
> REQUIRED_USE defaults).

Something along the lines of PYTHON_TARGETS could work. But
personally, I'm happy with REQUIRED_USE.

> In the meantime, we will apply the policies
> written in the Qt project wiki page.

Except for the one that is wrong.

>> In the meantime, we should stick with the policies adopted at the qt3
>> to qt4 transition (explicit versioned useflags) and let the user deal
>> with per-package management if they enable both flags.
>>
>
> We didn't have REQUIRED_USE at the time of the qt3->qt4 transition, so
> this point is completely moot.

We had something worse. That didn't prevent us from using it tho.

Ian Stakenvicius

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Aug 5, 2015, 5:30:02 PM8/5/15
to
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

I'm not aware of any either, although I haven't done a comprehensive
audit of the tree to find out. I would find it unlikely that any such
package exists.

The thing is, we're already travelling that road (have been for a long
while), and IMO there is very little "cost" to travelling this road
compared to the so-called "proper" solution of forcing off one flag or
the other, ESPECIALLY when we are likely to have both flags default-on
soon in the generic desktop profile as was posted earlier.

If we do go the REQUIRED_USE="^^" route on packages, then I think it
would be best that we change the 'desktop' and other profiles s.t.
maintainers need to add their package with whichever flag should be
enabled (qt4 or qt5) to package.use, rather than having the qt*
flag(s) globally enabled in the profile -- otherwise we end up with
end-users having to deal with it.

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Sergey Popov

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Aug 9, 2015, 3:40:02 PM8/9/15
to
<qa team lead hat>

In short - apropriate REQUIRED_USE with setting recommended
USE-flag(e.g. USE="+qt4 qt5" or USE="qt4 +qt5")

</qa team lead hat>

That's most painless decision for both developers and users. Developers
do not need to maintain ugly dependencies like

DEPEND="qt4 ? (
qt5 ( dev-qt/qtcore:5 )
!qt5 ( dev-qt/qtcore:4 )
)
...
"
and other mess.

</qa team lead hat>

Users will have default behaviour for empty make.conf. If they adjust
they make.conf to globally include/exclude some Qt-related USEs - they
are already moving from default and that's why - they can add apropriate
options to package.use


02.08.2015 19:34, Ben de Groot пишет:
> 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 and a
> REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the clearest choice.
>
> 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.
>
> --
> Cheers,
>
> Ben | yngwin
> Gentoo developer
>


--
Best regards, Sergey Popov
Gentoo developer
Gentoo Desktop-effects project lead
Gentoo Quality Assurance project lead
Gentoo Proxy maintainers project lead

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Alexandre Rostovtsev

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Aug 9, 2015, 4:10:03 PM8/9/15
to
On Sun, 2015-08-09 at 22:38 +0300, Sergey Popov wrote:
> <qa team lead hat>
>
> In short - apropriate REQUIRED_USE with setting recommended
> USE-flag(e.g. USE="+qt4 qt5" or USE="qt4 +qt5")
>
> </qa team lead hat>

If a package has optional guis, why should users of the default profile get any
gui enabled by default? The default profile usually means "headless server". It
means users who specifically don't need gtk, don't need qt4, don't need qt5,
don't need X.

So please don't + desktop-oriented USE flags in an ebuild's IUSE by default
unless the whole ebuild is intended mainly for desktop users.

> Users will have default behaviour for empty make.conf. If they adjust
> they make.conf to globally include/exclude some Qt-related USEs - they
> are already moving from default and that's why - they can add apropriate
> options to package.use

There is more than one "default" from which to move away. Different profiles
globally enable different flags. Desktop, gnome, and kde profiles already enable
qt4 globally. Plasma already enables qt4 and qt5 globally. And the desktop
profile will probably end up enabling qt4 and qt5 at some point.
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Davide Pesavento

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Aug 9, 2015, 4:10:03 PM8/9/15
to
On Sun, Aug 9, 2015 at 12:38 PM, Sergey Popov <pink...@gentoo.org> wrote:
> <qa team lead hat>
>
> In short - apropriate REQUIRED_USE with setting recommended
> USE-flag(e.g. USE="+qt4 qt5" or USE="qt4 +qt5")
>
> </qa team lead hat>
>
> That's most painless decision for both developers and users. Developers
> do not need to maintain ugly dependencies like
>
> DEPEND="qt4 ? (
> qt5 ( dev-qt/qtcore:5 )
> !qt5 ( dev-qt/qtcore:4 )
> )
> ...
> "
> and other mess.
>
> </qa team lead hat>
>
> Users will have default behaviour for empty make.conf. If they adjust
> they make.conf to globally include/exclude some Qt-related USEs - they
> are already moving from default and that's why - they can add apropriate
> options to package.use
>

Sergey,

It seems you completely ignored the discussion that took place in this
thread (and I also think you misunderstood the scenario judging from
the example you gave). Therefore I'm sorry but I will ignore your
opinion as QA team lead.

Thanks,
Davide

Ulrich Mueller

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Aug 9, 2015, 4:30:02 PM8/9/15
to
>>>>> On Sun, 09 Aug 2015, Sergey Popov wrote:

> <qa team lead hat>
> In short - apropriate REQUIRED_USE with setting recommended
> USE-flag(e.g. USE="+qt4 qt5" or USE="qt4 +qt5")

> </qa team lead hat>

> That's most painless decision for both developers and users. Developers
> do not need to maintain ugly dependencies like

> DEPEND="qt4 ? (
> qt5 ( dev-qt/qtcore:5 )
> !qt5 ( dev-qt/qtcore:4 )
> )
> ...
> "
> and other mess.

> </qa team lead hat>

I disagree with this. Really, REQUIRED_USE should be used sparingly,
and IMHO the above is not a legitimate usage case for it.

Ulrich

Alexander Berntsen

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Aug 10, 2015, 3:30:03 AM8/10/15
to
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On 09/08/15 21:38, Sergey Popov wrote:
> <qa team lead hat>
>
> In short - apropriate REQUIRED_USE with setting recommended
> USE-flag(e.g. USE="+qt4 qt5" or USE="qt4 +qt5")
>
> </qa team lead hat>
Strong -1.
- --
Alexander
bern...@gentoo.org
https://secure.plaimi.net/~alexander
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Sergey Popov

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Aug 11, 2015, 6:10:03 AM8/11/15
to
What's not clear with 'apropriate' word in my sentence?

Let me clarify - if package depend either on Qt4 or Qt5 and CAN not be
built with Qt at all - force this behaviour with REQUIRED_USE.

I think that it was obvious that i have meant exactly this case, cause
other cases are unreasonable here.

09.08.2015 23:07, Alexandre Rostovtsev пишет:
--
Best regards, Sergey Popov
Gentoo developer
Gentoo Desktop Effects project lead
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Sergey Popov

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Aug 11, 2015, 6:20:03 AM8/11/15
to
09.08.2015 23:28, Ulrich Mueller пишет:
> I disagree with this. Really, REQUIRED_USE should be used sparingly,
> and IMHO the above is not a legitimate usage case for it.

So, you prefer to make ugly mess of deps here like i posted before or
introduce some really unneded USE-flag like 'gui', 'qt', etc. to make
users even more confused?

Really, look at man-db ebuild. Especially on berkdb and gdbm USE flags.
And dependency string like this:

!berkdb? ( !gdbm? ( sys-libs/gdbm ) )

One sentence: "WHAT THE HELL?"

Imagine that it would be dozen of flags. Is it fun to mess with deps
like this for you?

--
Best regards, Sergey Popov
Gentoo developer
Gentoo Desktop Effects project lead
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Sergey Popov

unread,
Aug 11, 2015, 6:20:04 AM8/11/15
to
Err, i have read the whole thread and still does not get a point, why i
am wrong.

It's old battle like we have beforce with "gtk" meaning "any versions of
GTK flag". This behaviour should be killed with fire.

Let's me reiterate some of the cases:

1. Package can be build without Qt GUI at all, but either Qt4 or Qt5 can
be chosen, but not both.

Fix this with REQUIRED_USE, do not enable any of Qt flags by default

2. Package can not be build without Qt GUI - either Qt4 or Qt5 is
required, but not both

Same thing here, different REQUIRED_USE operator. But - enable one of
the flags by default to ease life of users.

3. Package can be build with Qt4 or Qt5 or both AT THE SAME TIME(if such
package even exists?)

Do not use REQUIRED_USE here, not needed.

Now, please tell me, where am i wrong?

09.08.2015 23:08, Davide Pesavento пишет:
--
Best regards, Sergey Popov
Gentoo developer
Gentoo Desktop Effects project lead
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Georg Rudoy

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Aug 11, 2015, 6:20:04 AM8/11/15
to
2015-08-11 11:10 GMT+01:00 Sergey Popov <pink...@gentoo.org>:
3. Package can be build with Qt4 or Qt5 or both AT THE SAME TIME(if such
package even exists?)

Take app-text/poppler as an "officially supported" example.

Take x11-libs/qwt as an example of a library that gets a patched library name to avoid collisions (at least, last time I looked into it).

I would argue this is a very desirably property for libraries in general. I even keep my own small overlay with Qt5-enabled versions of libraries like qxmpp, qtermwidget or liblastfm.
 
Do not use REQUIRED_USE here, not needed.

You missed the fourth option: the package can not be built without Qt GUI, but it supports building with either Qt version at the same time.

--
  Georg Rudoy

Sergey Popov

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Aug 11, 2015, 6:30:03 AM8/11/15
to
11.08.2015 13:18, Georg Rudoy пишет:
>
> You missed the fourth option: the package can not be built without Qt
> GUI, but it supports building with either Qt version at the same time.
>

Not a problem.

REQUIRED_USE="|| ( qt4 qt5 )"

At least one of flags should be enabled, but both can be enabled too(if
i understand your example correctly)
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Sergey Popov

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Aug 11, 2015, 6:50:03 AM8/11/15
to
I'd suggest to make a QA team meeting to override this policies with
more correct and rationale.

Qt team members are greatly appreciated on this meeting. Even more, i
think that we should not take any decision on this without at least Qt
team lead(or half of Qt team devs)

So, let's arrange some time and talk about this, cause it is really
confusing. Qt team point is understandable, but it's still wrong. Let's
make some consensus here.

02.08.2015 19:34, Ben de Groot пишет:
> 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 and a
> REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user the clearest choice.
>
> 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.
>
> --
> Cheers,
>
> Ben | yngwin
> Gentoo developer
>


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Michael Palimaka

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Aug 11, 2015, 8:40:03 AM8/11/15
to
On 11/08/15 20:17, Sergey Popov wrote:
> 09.08.2015 23:28, Ulrich Mueller пишет:
>> I disagree with this. Really, REQUIRED_USE should be used sparingly,
>> and IMHO the above is not a legitimate usage case for it.
>
> So, you prefer to make ugly mess of deps here like i posted before or
> introduce some really unneded USE-flag like 'gui', 'qt', etc. to make
> users even more confused?
>
> Really, look at man-db ebuild. Especially on berkdb and gdbm USE flags.
> And dependency string like this:
>
> !berkdb? ( !gdbm? ( sys-libs/gdbm ) )
>
> One sentence: "WHAT THE HELL?"
>
> Imagine that it would be dozen of flags. Is it fun to mess with deps
> like this for you?

Shall we ban this too?

ffmpeg? (
libav? ( media-video/libav:= )
!libav? ( media-video/ffmpeg:0= )
)

Michael Palimaka

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Aug 11, 2015, 8:40:04 AM8/11/15
to
On 11/08/15 20:10, Sergey Popov wrote:
> Err, i have read the whole thread and still does not get a point, why i
> am wrong.

You clearly have not. The reasoning behind Qt team's policy is described
on the page and has been reiterated on this list. You are undermining
what little confidence there is in the QA team by making decisions with
no consultation about problems you do not understand.

> It's old battle like we have beforce with "gtk" meaning "any versions of
> GTK flag". This behaviour should be killed with fire.
>
> Let's me reiterate some of the cases:
>
> 1. Package can be build without Qt GUI at all, but either Qt4 or Qt5 can
> be chosen, but not both.
>
> Fix this with REQUIRED_USE, do not enable any of Qt flags by default

Problem: this requires manual intervention if the user has both qt4 and
qt5 USE flags enabled.

>
> 2. Package can not be build without Qt GUI - either Qt4 or Qt5 is
> required, but not both
>
> Same thing here, different REQUIRED_USE operator. But - enable one of
> the flags by default to ease life of users.

Problem: this requires manual intervention if the user has both qt4 and
qt5 USE flags enabled.

>
> 3. Package can be build with Qt4 or Qt5 or both AT THE SAME TIME(if such
> package even exists?)
>
> Do not use REQUIRED_USE here, not needed.
>
> Now, please tell me, where am i wrong?
>

The problem is manual intervention is required if the user has both qt4
and qt5 USE flags enabled - and this is a common configuration. It is
not acceptable to make a user manually add numerous package.use entries
when all they want to do is install KDE.

I agree Qt's policy is not a perfect solution, but in the absence of
some feature allowing a preference to be set when there is a conflict
it's the best we've got.

Sergey Popov

unread,
Aug 11, 2015, 9:00:03 AM8/11/15
to
11.08.2015 15:30, Michael Palimaka пишет:
> On 11/08/15 20:10, Sergey Popov wrote:
>> Err, i have read the whole thread and still does not get a point, why i
>> am wrong.
>
> You clearly have not. The reasoning behind Qt team's policy is described
> on the page and has been reiterated on this list. You are undermining
> what little confidence there is in the QA team by making decisions with
> no consultation about problems you do not understand.
>
>> It's old battle like we have beforce with "gtk" meaning "any versions of
>> GTK flag". This behaviour should be killed with fire.
>>
>> Let's me reiterate some of the cases:
>>
>> 1. Package can be build without Qt GUI at all, but either Qt4 or Qt5 can
>> be chosen, but not both.
>>
>> Fix this with REQUIRED_USE, do not enable any of Qt flags by default
>
> Problem: this requires manual intervention if the user has both qt4 and
> qt5 USE flags enabled.
>

User choice of using USE flags is NOT a problem

>>
>> 2. Package can not be build without Qt GUI - either Qt4 or Qt5 is
>> required, but not both
>>
>> Same thing here, different REQUIRED_USE operator. But - enable one of
>> the flags by default to ease life of users.
>
> Problem: this requires manual intervention if the user has both qt4 and
> qt5 USE flags enabled.

Same here

>>
>> 3. Package can be build with Qt4 or Qt5 or both AT THE SAME TIME(if such
>> package even exists?)
>>
>> Do not use REQUIRED_USE here, not needed.
>>
>> Now, please tell me, where am i wrong?
>>
>
> The problem is manual intervention is required if the user has both qt4
> and qt5 USE flags enabled - and this is a common configuration. It is
> not acceptable to make a user manually add numerous package.use entries
> when all they want to do is install KDE.

And here

> I agree Qt's policy is not a perfect solution, but in the absence of
> some feature allowing a preference to be set when there is a conflict
> it's the best we've got.
>

If you want to go this way, then please provide helper functions in
eclasses to set dependencies properly for all common use cases. That
will ease life both of developers and users.

Leaving constructing of dependencies to developers in all cases will
cause only pain in your solution.

Look at the example with berkdb/gdbm, that i have posted recently.

If both of flags are not set - we stick to default.
Should this be set in EVERY ebuild explicitly?

Maybe provide some sugar like $(qt_use_default qtgui 5), where
qt_use_default is the name of function, qtgui is the package and 5 is
the slot for default choice, where either BOTH of flags(qt4, qt5) are
enabled or disabled
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Sergey Popov

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Aug 11, 2015, 9:10:02 AM8/11/15
to
11.08.2015 15:32, Michael Palimaka пишет:
No, because ffmpeg here is a feature AND name of concrete realization.
Not ideal case as i would said, but it is acceptable.

You want to migrate to such decision? Like:

qt? (
qt5? ( dev-lang/qtcore:5 )
!qt5? ( dev-lang/qtcore:4 )
)

Fine by me, if you would ask.

As i said one message earlier: Something like $(qt_use_default qtgui 5)

which will generate something like this:

qt4? (
qt5? ( dev-lang/qtcore:5 )
!qt5? ( dev-lang/qtcore:4 )
)
!qt5? ( !qt4? ( dev-lang/qtcore:5 ) )

would help too.

If you are doing complicated things(and please, do not tell me that
provided dependency string is simple and understandable by every
developer in just a second without wanting to "improve" or "simplify"
it) - do it through eclass. And provide nice API.

Thanks for listening and sorry if i was too harsh
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Sergey Popov

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Aug 11, 2015, 9:10:02 AM8/11/15
to
11.08.2015 16:04, Sergey Popov пишет:
Oops, sorry dev-qt/qtgui inside the brackets, of course.
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Sergey Popov

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Aug 11, 2015, 9:20:03 AM8/11/15
to
11.08.2015 16:11, James Le Cuirot пишет:
> On Tue, 11 Aug 2015 15:58:49 +0300
> Sergey Popov <pink...@gentoo.org> wrote:
>
>> If both of flags are not set - we stick to default.
>> Should this be set in EVERY ebuild explicitly?
>>
>> Maybe provide some sugar like $(qt_use_default qtgui 5), where
>> qt_use_default is the name of function, qtgui is the package and 5 is
>> the slot for default choice, where either BOTH of flags(qt4, qt5) are
>> enabled or disabled
>
> That sounds a little bit like what I suggested earlier.
>
> https://archives.gentoo.org/gentoo-dev/message/884257a2d924a51851d629b1dc9b30df
>

But without introducing brand new useless USE flag. Which makes huge
difference to me :-)
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