[gentoo-dev] ebuild USE priority

[gentoo-dev] ebuild USE priority

[Erik Grinaker]

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Hi all

I'm making an ebuild here, and have run into a small "problem".

The ebuild is for the Unix Amiga Emulator, or uae for short. uae allows
you to select which backend to compile against during ./configure, and
you can choose *either* x, svgalib, ncurses or sdl.

If a user has, say, both X and svga in his USE variable, how do I
determine whether to use X or svgalib for backend?

According to what I believe is common sense I would prioritize them as
X, sdl, svga, ncurses - but is there a better way to do this, or do I
just go by feeling?


-- 

Erik Grinaker
Freelance UNIX/Linux systems consultant

"Perfection is acheived not when there is nothing more to add, but
rather when there is nothing more to take away"
- Antoine de Saint-Exupéry


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Re: [gentoo-dev] ebuild USE priority

[Per Wigren]

I'd say that you should go for this order: SDL, X11, SVGA..
And don't forget to --enable-penguins! :) It doesn't make UAE slower (more 
than maybe 0.5%) on singleprocessor-systems, but it is noticably faster on 
SMP!

Hmm... Maybe there is a USE-variable for SMP? Or some other way to check it?

// Wigren

Wednesday 15 May 2002 00.23 skrev Erik Grinaker:
> Hi all
>
> I'm making an ebuild here, and have run into a small "problem".
>
> The ebuild is for the Unix Amiga Emulator, or uae for short. uae allows
> you to select which backend to compile against during ./configure, and
> you can choose *either* x, svgalib, ncurses or sdl.
>
> If a user has, say, both X and svga in his USE variable, how do I
> determine whether to use X or svgalib for backend?
>
> According to what I believe is common sense I would prioritize them as
> X, sdl, svga, ncurses - but is there a better way to do this, or do I
> just go by feeling?

Re: [gentoo-dev] ebuild USE priority

[Spider]

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begin  quote
On 15 May 2002 00:23:18 +0200
Erik Grinaker <erikg@wired-networks.net> wrote:
> 
> According to what I believe is common sense I would prioritize them as
> X, sdl, svga, ncurses - but is there a better way to do this, or do I
> just go by feeling?



I'd actually say: 
sdl, X, svga, ncurses ...   

mostly based on the fact that SDL is a layer over X 

//Spider

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Re: [gentoo-dev] ebuild USE priority

[Erik Grinaker]

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On Wed, 2002-05-15 at 01:53, Spider wrote:

> On 15 May 2002 00:23:18 +0200
> Erik Grinaker <erikg@wired-networks.net> wrote:
> > According to what I believe is common sense I would prioritize them as
> > X, sdl, svga, ncurses - but is there a better way to do this, or do I
> > just go by feeling?
> 
> I'd actually say: 
> sdl, X, svga, ncurses ...   
> 
> mostly based on the fact that SDL is a layer over X 

true - but when i tested it sdl was waaaaay slower than x - and as many
users most probably have sdl enabled, perhaps without even knowing, i
thought x would be a sensible default.


-- 

Erik Grinaker
Freelance UNIX/Linux systems consultant

"Perfection is acheived not when there is nothing more to add, but
rather when there is nothing more to take away"
- Antoine de Saint-Exupéry


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Re: [gentoo-dev] ebuild USE priority

[Spider]

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begin  quote
On 15 May 2002 02:44:28 +0200
Erik Grinaker <erikg@wired-networks.net> wrote:

> true - but when i tested it sdl was waaaaay slower than x - and as
> many users most probably have sdl enabled, perhaps without even
> knowing, i thought x would be a sensible default.


then go for that :) 

//Spider
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Re: [gentoo-dev] ebuild USE priority

[Matthew Kennedy]

On Tue, 2002-05-14 at 17:23, Erik Grinaker wrote:
> The ebuild is for the Unix Amiga Emulator, or uae for short. uae allows
> you to select which backend to compile against during ./configure, and
> you can choose *either* x, svgalib, ncurses or sdl.

When creating the xemacs-gamma ebuild I encountered the same dillema.
When you say "*either*", I assume you mean that X, svga, ncurse and sdl
are optional, but mutually exclusive.

> If a user has, say, both X and svga in his USE variable, how do I
> determine whether to use X or svgalib for backend?

XEmacs gamma supports gtk OR motif OR lucid interfaces (each of which
can be considered a use flag) in mutual exclusion. Of course, I don't
want to dictate one of those three to the user, since my preference may
not be theirs.

I thought of a priority scheme, but couldn't see clearly how that would
be done. How did you do it, BTW?

What I ended up doing was checking for an env. var. named USE_PREF which
is localized to xemacs-gamma. It allows the user to merge xemacs-gamma
like this:

   USE_PREF=gtk app-editors/xemacs-gamma

Inside the ebuild, I have a case statement which set the ./configure
flags based on the value of USE_PREF. If no USE_PREF is given, then it
defaults to a reasonable choice ("lucid" in xemacs-gamma's case).

*** Note: USE_PREF is undocumented of course, unused by any other
package AFAIK, and not an official Gentoo thing. ***

Personally, I think my USE_PREF implementation sucks still because it
really messes up RDEPEND/DEPEND. ie. RDEPEND/DEPEND become a function of
USE_PREF.

Perhaps I should have created the following?

   app-editors/xemacs-gamma-gtk
   app-editors/xemacs-gamma-lucid
   app-editors/xemacs-gamma-motif

Ugh. What if you have two sets of mutually exclusive USE flags -- just
multiply out the number of ebuilds you create.

Perhaps I could have one app-editors/xemacs-gamma and build xemacs
several times (one build for every use flag in gtk, motif, lucid),
renaming the final binaries to /usr/bin/xemacs-21.4.8-{gtk,motif,lucid}.
Even provide an xemacs-update script in the spirit of
opengl-update/java-config just to complete my madness :)

(ie. It's not possible to build a gtk, motif AND lucid based xemacs in a
single ./configure)

> According to what I believe is common sense I would prioritize them as
> X, sdl, svga, ncurses - but is there a better way to do this, or do I

Are you using the order in which X, sdl and svga appear in USE? What if
I have X and svga in USE, but I want an svga amiga emulator? That's kind
dillema I'm talking about.

Matt

Re: [gentoo-dev] ebuild USE priority

[Erik Grinaker]

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On Wed, 2002-05-15 at 06:55, Matthew Kennedy wrote:

> On Tue, 2002-05-14 at 17:23, Erik Grinaker wrote:
> > The ebuild is for the Unix Amiga Emulator, or uae for short. uae allows
> > you to select which backend to compile against during ./configure, and
> > you can choose *either* x, svgalib, ncurses or sdl.
> 
> When creating the xemacs-gamma ebuild I encountered the same dillema.
> When you say "*either*", I assume you mean that X, svga, ncurse and sdl
> are optional, but mutually exclusive.

Yep, that's right.


> > If a user has, say, both X and svga in his USE variable, how do I
> > determine whether to use X or svgalib for backend?
> 
> XEmacs gamma supports gtk OR motif OR lucid interfaces (each of which
> can be considered a use flag) in mutual exclusion. Of course, I don't
> want to dictate one of those three to the user, since my preference may
> not be theirs.
> 
> I thought of a priority scheme, but couldn't see clearly how that would
> be done. How did you do it, BTW?

Well, I haven't completed the ebuild yet, but I decided to go for my own
priorities ;

    use ncurses &&  backend="--with-asciiart"
    use svga &&     backend="--with-svgalib"
    use sdl &&      backend="--with-sdl --with-sdl-sound --with-sdl-gfx"
    use X &&        backend="--with-x"

These are set in reverse so that the last one that matches will be
active. But I'm really not satisfied with this, because if a user would
like to have, as you say later in your mail, an svga emulator while
having both x and svga in his USE then his only option would be to
manually change USE before emerging.


> What I ended up doing was checking for an env. var. named USE_PREF which
> is localized to xemacs-gamma. It allows the user to merge xemacs-gamma
> like this:
> 
>    USE_PREF=gtk app-editors/xemacs-gamma

This seems to be quite sensible, even though it creates it's share of
troubles when checking DEPENDs. Does any of the Gentoo developers have
any thoughts on this?


-- 

Erik Grinaker
Freelance UNIX/Linux systems consultant

"Perfection is acheived not when there is nothing more to add, but
rather when there is nothing more to take away"
- Antoine de Saint-Exupéry


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