[gentoo-dev] Re: use flags -> use options

[gentoo-dev] Re: use flags -> use options

[Christian Faulhammer]

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"Marijn Schouten (hkBst)" <hkBst@gentoo.org>:
> I imagine there are a lot more cases where the simple on/off system
> we have now is suboptimal. I could be wrong of course. Please comment.

 This key=value systems sounds interesting.  Another use could be the
choice between xulrunner, seamonkey, firefox. 

V-Li

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Christian Faulhammer, Gentoo Lisp project
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<URL:http://www.faulhammer.org/>

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Re: [gentoo-dev] Re: use flags -> use options

[Tobias Klausmann]

Hi! 

On Sun, 07 Oct 2007, Christian Faulhammer wrote:

> "Marijn Schouten (hkBst)" <hkBst@gentoo.org>:
> > I imagine there are a lot more cases where the simple on/off system
> > we have now is suboptimal. I could be wrong of course. Please comment.
> 
>  This key=value systems sounds interesting.  Another use could be the
> choice between xulrunner, seamonkey, firefox. 

And maybe it can be alleviated for some of the virtuals problem
space. For those apps that need an editor, one could think of
editor=vim.

That would then of course raise the question of a sensible
default - as it is with virtual/editor right now.

Generally, its prime area of use is where something can be
turned off (foo=off) or turned on with different ways of getting
the functionality (foo=gnufoo, foo=freefoo, foo=foong).

Another thing to keep in mind is though, that gnufoo might not
have all the nifty-but-patent-ridden stuff that freefoo has. Then
again, the user/sysadmin should know which of those fits the
bill. The question would only be how to convey this info to the
admin.

Regards,
Tobias

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Re: [gentoo-dev] Re: use flags -> use options

[Jan Kundrát]

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Tobias Klausmann wrote:
> For those apps that need an editor, one could think of editor=vim.

USE flag change usually triggers a rebuild of the package in question. I
certainly don't want to rebuild packages just because I switch $EDITOR.

Cheers,
-jkt

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Re: [gentoo-dev] Re: use flags -> use options

[Drake Wyrm]

Jan Kundr?t <jkt@gentoo.org> wrote:
> Tobias Klausmann wrote:
> > For those apps that need an editor, one could think of editor=vim.
> 
> USE flag change usually triggers a rebuild of the package in question. I
> certainly don't want to rebuild packages just because I switch $EDITOR.

If there's a compile-time dependency on an editor, usually meaning that
the path to an editor is hardcoded into some binary, then you most
certainly _do_ want to recompile when you switch the system editor.
Otherwise, those packages will fail when you remove the old editor.

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Re: [gentoo-dev] Re: use flags -> use options

[Marius Mauch]

On Sun, 7 Oct 2007 21:12:25 +0200
Tobias Klausmann <klausman@schwarzvogel.de> wrote:

> Hi! 
> 
> On Sun, 07 Oct 2007, Christian Faulhammer wrote:
> 
> > "Marijn Schouten (hkBst)" <hkBst@gentoo.org>:
> > > I imagine there are a lot more cases where the simple on/off
> > > system we have now is suboptimal. I could be wrong of course.
> > > Please comment.
> > 
> >  This key=value systems sounds interesting.  Another use could be
> > the choice between xulrunner, seamonkey, firefox. 

We already have this with USE_EXPAND. Not exactly the same syntax, but
I don't see a terrible problem in that, and we don't have to fix all
three trillion related tools to handle it. Unless you can come up
with a case that can't be handled with USE_EXPAND.

> And maybe it can be alleviated for some of the virtuals problem
> space. For those apps that need an editor, one could think of
> editor=vim.

I don't see how this is related at all, as the packages need an editor,
but don't care which editor. So what would USE="editor=vim" do?

Marius
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Re: [gentoo-dev] Re: use flags -> use options

[Marijn Schouten (hkBst)]

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Marius Mauch wrote:
>>> "Marijn Schouten (hkBst)" <hkBst@gentoo.org>:
>>>> I imagine there are a lot more cases where the simple on/off
>>>> system we have now is suboptimal. I could be wrong of course.
>>>> Please comment.
>>>  This key=value systems sounds interesting.  Another use could be
>>> the choice between xulrunner, seamonkey, firefox. 
> 
> We already have this with USE_EXPAND. Not exactly the same syntax, but
> I don't see a terrible problem in that, and we don't have to fix all
> three trillion related tools to handle it. Unless you can come up
> with a case that can't be handled with USE_EXPAND.

No, USE_EXPAND is only a way to abbreviate use flags with a common substring
in their name, such as "impl_guile impl_sbcl impl_clisp" which could be
encoded interchangeably as either

# without USE_EXPAND
IUSE="impl_guile impl_sbcl impl_clisp"

or

# with USE_EXPAND
for impl in IMPL; do IUSE+="impl_${impl}"; done

but the effect is that there are 3 use flags with a total of 2^3=8
combinations, while really something with exactly 3 combinations is needed:

IUSE="impl"

case ${impl} in
	guile)  #use guile as backend
	 sbcl)  #use sbcl  as backend
	clisp)  #use clisp as backend

or something like that.

Marijn

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Marijn Schouten (hkBst), Gentoo Lisp project
<http://www.gentoo.org/proj/en/lisp/>, #gentoo-lisp on FreeNode
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[gentoo-dev] Re: use flags -> use options

[Ryan Hill]

Marijn Schouten (hkBst) wrote:
> Marius Mauch wrote:

>> We already have this with USE_EXPAND. Not exactly the same syntax, but
>> I don't see a terrible problem in that, and we don't have to fix all
>> three trillion related tools to handle it. Unless you can come up
>> with a case that can't be handled with USE_EXPAND.
 
> No, USE_EXPAND is only a way to abbreviate use flags with a common substring
> in their name, such as "impl_guile impl_sbcl impl_clisp" which could be
> encoded interchangeably as either

You're kidding, right?

> USE EXPAND Defines a list of variables which are to be treated incrementally and who
>       contents are to be expanded into the USE variable as passed to ebuilds. Expansion 
>       done as per Algorithm 2. So, for example, if USE EXPAND contains ‘ALSA CARDS’, an
>       the ALSA CARDS variable contains ‘foo’, ‘alsa_cards_foo’ will be appended to USE.

> Algorithm 2: USE EXPAND logic
>   for each variable V listed in USE EXPAND do
>     for each token T in V do
>         append v_T to USE, where v is the lowercase of V
>     end for
>   end for


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Re: [gentoo-dev] Re: use flags -> use options

[Marijn Schouten (hkBst)]

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Ryan Hill wrote:
> Marijn Schouten (hkBst) wrote:
>> Marius Mauch wrote:
> 
>>> We already have this with USE_EXPAND. Not exactly the same syntax, but
>>> I don't see a terrible problem in that, and we don't have to fix all
>>> three trillion related tools to handle it. Unless you can come up
>>> with a case that can't be handled with USE_EXPAND.
>  
>> No, USE_EXPAND is only a way to abbreviate use flags with a common substring
>> in their name, such as "impl_guile impl_sbcl impl_clisp" which could be
>> encoded interchangeably as either
> 
> You're kidding, right?

No, if what I'm saying makes no sense it is ignorance. Please enlighten me.

Marijn

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Re: [gentoo-dev] Re: use flags -> use options

[Marius Mauch]

On Mon, 08 Oct 2007 13:45:04 +0200
"Marijn Schouten (hkBst)" <hkBst@gentoo.org> wrote:

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> 
> Marius Mauch wrote:
> >>> "Marijn Schouten (hkBst)" <hkBst@gentoo.org>:
> >>>> I imagine there are a lot more cases where the simple on/off
> >>>> system we have now is suboptimal. I could be wrong of course.
> >>>> Please comment.
> >>>  This key=value systems sounds interesting.  Another use could be
> >>> the choice between xulrunner, seamonkey, firefox. 
> > 
> > We already have this with USE_EXPAND. Not exactly the same syntax,
> > but I don't see a terrible problem in that, and we don't have to
> > fix all three trillion related tools to handle it. Unless you can
> > come up with a case that can't be handled with USE_EXPAND.
> 
> No, USE_EXPAND is only a way to abbreviate use flags with a common
> substring in their name, such as "impl_guile impl_sbcl impl_clisp"
> which could be encoded interchangeably as either
> 
> # without USE_EXPAND
> IUSE="impl_guile impl_sbcl impl_clisp"
> 
> or
> 
> # with USE_EXPAND
> for impl in IMPL; do IUSE+="impl_${impl}"; done
> 
> but the effect is that there are 3 use flags with a total of 2^3=8
> combinations, while really something with exactly 3 combinations is
> needed:
> 
> IUSE="impl"
> 
> case ${impl} in
> 	guile)  #use guile as backend
> 	 sbcl)  #use sbcl  as backend
> 	clisp)  #use clisp as backend

So what you want is a USE_EXPAND version that only allows one value
per variable. That wouldn't be terribly difficult to do.
As for your idea (ignoring implementation issues), I'd expect that
sooner or later people will request multivalue functionality as well,
so we'd have the same situation there. Also in the given example, how
would the user/package manager actually know what values were
valid/available for "impl"?

Marius
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Re: [gentoo-dev] Re: use flags -> use options

[Marijn Schouten (hkBst)]

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Marius Mauch wrote:
> So what you want is a USE_EXPAND version that only allows one value
> per variable. That wouldn't be terribly difficult to do.

I extremely dislike that characterization. What I want is use flags with more
than two possible values. I see no reason to warp that to fit USE_EXPAND.
There may even be uses where this could be used in combination with USE_EXPAND.

> As for your idea (ignoring implementation issues), I'd expect that
> sooner or later people will request multivalue functionality as well,
> so we'd have the same situation there.

Right, current use flags are "2 options, pick 1", I am requesting "n options,
pick 1" and you're saying "n options, pick m, (m<n)" might be useful too.

But "n options, pick m, (m<n)" reduces to n times "2 options, pick 1" (you
decide for each possible value whether to include it or not). This is exactly
why our "2 options, pick 1" system works so well most of the time.

> Also in the given example, how
> would the user/package manager actually know what values were
> valid/available for "impl"?

That is a good question. If all possible options need to be specified a syntax
should be developed for that. How about:

IUSE="+default_on_flag normalflag
multiwayflag={option1,option2,+default_option} -default_off_flag",

or

IUSE="+default_on_flag normalflag multiwayflag={option1 option2
+default_option} -default_off_flag",

or

IUSE="+default_on_flag normalflag multiwayflag=(option1 option2
+default_option) -default_off_flag".

In use.[local.]desc the multiwayflag description should explain what each
alternative means.

Marijn

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