[gentoo-dev] GLEP 29 (USE groups) and negatives

[gentoo-dev] GLEP 29 (USE groups) and negatives

[Ciaran McCreesh]

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http://www.gentoo.org/proj/en/glep/glep-0029.html

We need to decide upon a solution to the -flags problem. The proposed
solutions are:

1) Disallow all negatives. Disadvantages: we don't tend to disallow
things just because users could shoot themselves in the foot with them.

2) Allow negatives, and document how to use them correctly.
Disadvantages: sooner or later, some developer isn't going to read the
docs, and will really really screw things up with a misunderstanding.

3) Reorder USE flags. Disadvantages: can't disable flags set by a group.
Breaks existing USE lines.

4) Have portage warn on dodgy USE flag lines. Disadvantages: tricky,
hard for the end user to figure out.

5) Use some weird tristate notation. Disadvantages: not everyone has the
slightest clue what set theory is.

I'm in favour of 2) personally, but others disagree. I'd like a proper
discussion on this before trying to get the GLEP through.

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, shell tools)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Maurice van der Pot]

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On Sun, Mar 06, 2005 at 04:28:49PM +0000, Ciaran McCreesh wrote:
> http://www.gentoo.org/proj/en/glep/glep-0029.html
> 
> We need to decide upon a solution to the -flags problem. The proposed
> solutions are:
> 
> 1) Disallow all negatives. Disadvantages: we don't tend to disallow
> things just because users could shoot themselves in the foot with them.
> 
> 2) Allow negatives, and document how to use them correctly.
> Disadvantages: sooner or later, some developer isn't going to read the
> docs, and will really really screw things up with a misunderstanding.
> 
...
>
> 5) Use some weird tristate notation. Disadvantages: not everyone has the
> slightest clue what set theory is.

'some weird tristate notation' must be what I proposed previously. =)

I'm still convinced that the use of it would be easy, both for
developers and for users, but I do acknowledge some (minor) issues like
finding another usable character for the new notation.

The last time I tried to explain my proposal, everybody except myself
seemed to think it was complicated, so I will not try to promote it
anymore, it's in the archives already.

> I'm in favour of 2) personally, but others disagree. I'd like a proper
> discussion on this before trying to get the GLEP through.

What I am still missing is a good argument _FOR_ negatives. We are
talking about negatives within groups, right? I agree with you that if
we choose 2, sooner or later it's going to get screwed up. We must have
a better reason for allowing them than just the off chance that negatives 
might be useful in a way we cannot forsee yet.

If there is such a reason, I'd also pick 2.

Maurice.

-- 
Maurice van der Pot

Gentoo Linux Developer   griffon26@gentoo.org     http://www.gentoo.org
Creator of BiteMe!       griffon26@kfk4ever.com   http://www.kfk4ever.com


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Ciaran McCreesh]

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On Mon, 7 Mar 2005 20:24:15 +0100 Maurice van der Pot
<griffon26@gentoo.org> wrote:

| > I'm in favour of 2) personally, but others disagree. I'd like a
| > proper discussion on this before trying to get the GLEP through.
| 
| What I am still missing is a good argument _FOR_ negatives. We are
| talking about negatives within groups, right? I agree with you that if
| we choose 2, sooner or later it's going to get screwed up. We must
| have a better reason for allowing them than just the off chance that
| negatives  might be useful in a way we cannot forsee yet.

Reasons we want to allow negatives:
* They are useful in certain situations.
* They could reasonably be expected to work -- negatives work in other
places.
* Not supporting negatives simply because they cause complications is
basically admitting that we suck.

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, shell tools)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Maurice van der Pot]

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On Tue, Mar 08, 2005 at 03:21:17PM +0000, Ciaran McCreesh wrote:
> On Mon, 7 Mar 2005 20:24:15 +0100 Maurice van der Pot
> <griffon26@gentoo.org> wrote:
> 
> Reasons we want to allow negatives:
> * They are useful in certain situations.

Can you give an example?

> * They could reasonably be expected to work -- negatives work in other
> places.

I don't doubt that it will work.

> * Not supporting negatives simply because they cause complications is
> basically admitting that we suck.

Only if we are the reason this particular implementation of negatives is
chosen. You won't catch me saying either one of these is an optimal
solution. In this case I think we're trying to select the lesser evil.

Regards,
Maurice.

-- 
Maurice van der Pot

Gentoo Linux Developer   griffon26@gentoo.org     http://www.gentoo.org
Creator of BiteMe!       griffon26@kfk4ever.com   http://www.kfk4ever.com


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Ciaran McCreesh]

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On Tue, 8 Mar 2005 18:35:03 +0100 Maurice van der Pot
<griffon26@gentoo.org> wrote:
| On Tue, Mar 08, 2005 at 03:21:17PM +0000, Ciaran McCreesh wrote:
| > On Mon, 7 Mar 2005 20:24:15 +0100 Maurice van der Pot
| > <griffon26@gentoo.org> wrote:
| > 
| > Reasons we want to allow negatives:
| > * They are useful in certain situations.
| 
| Can you give an example?

No, but klieber probably can, since he was the main proponent of not
disallowing negatives.

Having said that, "I can't think of one" is by no means equal to "there
are none". I can't think of any reason why anyone would ever possibly
want to use XML for anything, for example, but I'm sure *someone*
somewhere out there has a legit use for it.

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, shell tools)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Olivier Crête]

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On Tue, 2005-08-03 at 22:41 +0000, Ciaran McCreesh wrote:
> On Tue, 8 Mar 2005 18:35:03 +0100 Maurice van der Pot <griffon26@gentoo.org> wrote:
> | On Tue, Mar 08, 2005 at 03:21:17PM +0000, Ciaran McCreesh wrote:
> | > On Mon, 7 Mar 2005 20:24:15 +0100 Maurice van der Pot <griffon26@gentoo.org> wrote:
> | > 
> | > Reasons we want to allow negatives:
> | > * They are useful in certain situations.
> | 
> | Can you give an example?
> 
> No, but klieber probably can, since he was the main proponent of not
> disallowing negatives.
> 
> Having said that, "I can't think of one" is by no means equal to "there
> are none". I can't think of any reason why anyone would ever possibly
> want to use XML for anything, for example, but I'm sure *someone*
> somewhere out there has a legit use for it.

But when no one on gentoo-dev can give one, that might be a hint that's
its not worth taking time to do.

-- 
Olivier Crête
tester@gentoo.org
Gentoo Developer
x86 Security Liaison

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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Jason Wever]

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On Tue, 8 Mar 2005, Ciaran McCreesh wrote:

> On Tue, 8 Mar 2005 18:35:03 +0100 Maurice van der Pot
> | Can you give an example?
>
> No, but klieber probably can, since he was the main proponent of not
> disallowing negatives.

All of these double negatives to express a positive is making me go (more) 
cross-eyed. :)

- -- 
Jason Wever
Gentoo/Sparc Co-Team Lead
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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Philip Webb]

050306 Ciaran McCreesh wrote:
> We need to decide upon a solution to the -flags problem.
> The proposed solutions are:
> 1) Disallow all negatives. Disadvantages: we don't tend to disallow things
> just because users could shoot themselves in the foot with them.

that's not a disadvantage, let alone a plural of them (smile):
it's a tradition or merely a long-standing practice.

is there an actual disadvantage to disallowing all negatives ?
if not, that seems to be the simplest & least troublesome alternative.

-- 
========================,,============================================
SUPPORT     ___________//___,  Philip Webb : purslow@chass.utoronto.ca
ELECTRIC   /] [] [] [] [] []|  Centre for Urban & Community Studies
TRANSIT    `-O----------O---'  University of Toronto
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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Jerome Brown]

Ciaran McCreesh wrote:
> http://www.gentoo.org/proj/en/glep/glep-0029.html
> 
> We need to decide upon a solution to the -flags problem. The proposed
> solutions are:
> 
> 1) Disallow all negatives. Disadvantages: we don't tend to disallow
> things just because users could shoot themselves in the foot with them.
> 
> 2) Allow negatives, and document how to use them correctly.
> Disadvantages: sooner or later, some developer isn't going to read the
> docs, and will really really screw things up with a misunderstanding.
> 
> 3) Reorder USE flags. Disadvantages: can't disable flags set by a group.
> Breaks existing USE lines.
> 
> 4) Have portage warn on dodgy USE flag lines. Disadvantages: tricky,
> hard for the end user to figure out.
> 
> 5) Use some weird tristate notation. Disadvantages: not everyone has the
> slightest clue what set theory is.
> 
> I'm in favour of 2) personally, but others disagree. I'd like a proper
> discussion on this before trying to get the GLEP through.
> 
How about another option?

6) Disallow -USE within groups, but allow -@GROUP

Looking through the GLEP, I notice that the examples of where problems
of allowing -USE flags in a group could be resolved by not allowing the
-USE but allowing -@GROUP. For example, the usage of @KDE and @GNOME
groups in the glep looks like this:

<quote glep>
If, for example, the KDE group turned off GNOME things and the GNOME
group turned off KDE things:

KDE X kde qt -gtk -gnome
GNOME X gtk gtk2 gnome -kde -qt

And a user wished to use both KDE and GNOME on a system, and so had USE
flags as follows:

USE="@KDE @GNOME"

They would end up with:

USE="X kde qt -gtk -gnome X gtk gtk2 gnome -kde -qt"

Which simplifies:

USE="X gtk gtk2 gnome -kde -qt"

This is clearly not the desired effect.
</quote>

If, however we disallowed negatives in the group, you would define them as:

KDE X kde qt
GNOME X gtk gtk2 gnome

Therefore to get the desired effect of the originally suggested @KDE or
@GNOME the user would put:

USE="@KDE -@GNOME" or
USE="@GNOME -@KDE"

and to get both would have

USE="@KDE @GNOME"

which would resolve correctly.

The issue comes with resolving the individual (@KDE -@GNOME or vice
versa) as both define X, and a -X comes from the other. I guess that
this could be resolved by defining that if a USE flag is defined in a
group, and another group negates it, that portage ignores the negation,
however if the negation is specified by the user in their USE line then
the negation is allowed: Therefore

USE="@GNOME -@KDE"

would resolve to

USE="X gtk gtk2 gnome -kde -qt"

and

USE="@GNOME -X"

would resolve to

USE="gtk gtk2 gnome -X"

Just my 0.02 Universal Currency
-- 
Jerome Brown
Technology Architect
Hub.Net

P: +64  3 961-5116
M: +64 29 453 7663
F: +64  3 961-5129
E: jerome@hub.net.nz
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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Chris Gianelloni]

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On Wed, 2005-03-09 at 08:14 +1300, Jerome Brown wrote:
> How about another option?
> 
> 6) Disallow -USE within groups, but allow -@GROUP

I like this option.

> The issue comes with resolving the individual (@KDE -@GNOME or vice
> versa) as both define X, and a -X comes from the other. I guess that
> this could be resolved by defining that if a USE flag is defined in a
> group, and another group negates it, that portage ignores the negation,
> however if the negation is specified by the user in their USE line then
> the negation is allowed: Therefore

Why is X in either GNOME or KDE anyway?  It is separate from either, and
should probably have its own group, if necessary.

When I think of KDE stuff, I don't think of X + KDE, I think of KDE and
arts and Qt.  I think of X as a separate beast entirely.

Then again, I don't think that flags should be specified in more than
one group.

If it doesn't fit into a group, then don't group it.  If it fits into
multiple groups, then either pick one and stick with it, or don't group
it.

Groups are supposed to simplify using large numbers of USE flags, it
isn't supposed to completely replace them.

-- 
Chris Gianelloni
Release Engineering - Strategic Lead/QA Manager
Games - Developer
Gentoo Linux

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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Jerome Brown]

Chris Gianelloni wrote:
> On Wed, 2005-03-09 at 08:14 +1300, Jerome Brown wrote:
> 
>>How about another option?
>>
>>6) Disallow -USE within groups, but allow -@GROUP
> 
> 
<snip>
> Then again, I don't think that flags should be specified in more than
> one group.
> 
> If it doesn't fit into a group, then don't group it.  If it fits into
> multiple groups, then either pick one and stick with it, or don't group
> it.

I agree on this point, but wonder if it will be too restrictive to
enforce. Also, with to proposal to allow users to create their own
groups, they may want a unique combination of flags which they setup in
their overlay, which would violate the only in one group idea.

The other place that a flag may need to be in multiple groups could be
where local use flags are concerned, and they are related differently.
(I know this is an unlikely situation, but then we are Gentoo Users and
want to push the environs of what is possible/reasonable :) )

-- 
Jerome Brown
Technology Architect
Hub.Net

P: +64  3 961-5116
M: +64 29 453 7663
F: +64  3 961-5129
E: jerome@hub.net.nz
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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Ciaran McCreesh]

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On Tue, 08 Mar 2005 14:51:04 -0500 Chris Gianelloni
<wolf31o2@gentoo.org> wrote:
| On Wed, 2005-03-09 at 08:14 +1300, Jerome Brown wrote:
| > How about another option?
| > 
| > 6) Disallow -USE within groups, but allow -@GROUP
| 
| I like this option.

Ok, yeah, I'll buy that as a definite possibility.

| Why is X in either GNOME or KDE anyway?  It is separate from either,
| and should probably have its own group, if necessary.

Because in general, if a user wants a typical GNOME desktop, they'll
want the X USE flag enabled. Or at least, I assume they will...

| Then again, I don't think that flags should be specified in more than
| one group.

Way too limiting. Some flags are entirely worthwhile in more than one
context. Groups aren't primarily for categorisation, they're there for
quick USE selection.

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, shell tools)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Maurice van der Pot]

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On Tue, Mar 08, 2005 at 10:43:14PM +0000, Ciaran McCreesh wrote:
> On Tue, 08 Mar 2005 14:51:04 -0500 Chris Gianelloni
> <wolf31o2@gentoo.org> wrote:
> | On Wed, 2005-03-09 at 08:14 +1300, Jerome Brown wrote:
> | > How about another option?
> | > 
> | > 6) Disallow -USE within groups, but allow -@GROUP
> | 
> | I like this option.
> 
> Ok, yeah, I'll buy that as a definite possibility.

As I said earlier:
> We are talking about negatives within groups, right? 

Was my assumption incorrect?

Maurice.


P.S.: Ciaran, have you had enough caffeine yet for another look 
at your GLEP? I think there's an error in the example in the section 
named "Using Groups": the expansion of @GROUP2 in the third line from
the bottom.

-- 
Maurice van der Pot

Gentoo Linux Developer   griffon26@gentoo.org     http://www.gentoo.org
Creator of BiteMe!       griffon26@kfk4ever.com   http://www.kfk4ever.com


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Ciaran McCreesh]

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On Wed, 9 Mar 2005 13:54:12 +0100 Maurice van der Pot
<griffon26@gentoo.org> wrote:
| As I said earlier:
| > We are talking about negatives within groups, right? 
| 
| Was my assumption incorrect?

There are issues with both negatives *inside* groups and *outside*
groups. The ideal solution would solve both.

| P.S.: Ciaran, have you had enough caffeine yet for another look 
| at your GLEP? I think there's an error in the example in the section 
| named "Using Groups": the expansion of @GROUP2 in the third line from
| the bottom.

Entirely possible. Those examples will be redone to use sane names and
examples once the actual rules are decided upon.

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, shell tools)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm


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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Luca Barbato]

Jerome Brown wrote:
> 
> 6) Disallow -USE within groups, but allow -@GROUP
> 

I like it

as fallback, I'm not against 2

 > 2) Allow negatives, and document how to use them correctly.

lu

-- 

Luca Barbato

Gentoo/linux Developer		Gentoo/PPC Operational Manager
http://dev.gentoo.org/~lu_zero

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Re: [gentoo-dev] GLEP 29 (USE groups) and negatives

[Marius Mauch]

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On Sun, 6 Mar 2005 16:28:49 +0000
Ciaran McCreesh <ciaranm@gentoo.org> wrote:

> http://www.gentoo.org/proj/en/glep/glep-0029.html
> 
> We need to decide upon a solution to the -flags problem. The proposed
> solutions are:
> 
> 1) Disallow all negatives. Disadvantages: we don't tend to disallow
> things just because users could shoot themselves in the foot with
> them.
> 
> 2) Allow negatives, and document how to use them correctly.
> Disadvantages: sooner or later, some developer isn't going to read the
> docs, and will really really screw things up with a misunderstanding.
> 
> 3) Reorder USE flags. Disadvantages: can't disable flags set by a
> group. Breaks existing USE lines.
> 
> 4) Have portage warn on dodgy USE flag lines. Disadvantages: tricky,
> hard for the end user to figure out.
> 
> 5) Use some weird tristate notation. Disadvantages: not everyone has
> the slightest clue what set theory is.
> 
> I'm in favour of 2) personally, but others disagree. I'd like a proper
> discussion on this before trying to get the GLEP through.

Hmm, are talking about what should be technically possible or what
should be supported? Personally I'd like to have negatives available
but label them as unsupported ("if you play with this it's all your
fault"), that would also mean that predefined groups don't use them.

Marius

-- 
Public Key at http://www.genone.de/info/gpg-key.pub

In the beginning, there was nothing. And God said, 'Let there be
Light.' And there was still nothing, but you could see a bit better.

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