Hello

Please see attached news item for reviewing as part of the fix for
http://bugs.gentoo.org/show_bug.cgi?id=346491

Thanks

Title: Change on CAMERAS handling in libgphoto2-2.4.10
Author: Pacho Ramos <pacho@gentoo.org>
Content-Type: text/plain
Posted: 2011-02-13
Revision: 1
News-Item-Format: 1.0
Display-If-Installed: <media-libs/libgphoto2-2.4.10

In order to not violate package manager handling (http://bugs.gentoo.org/346491),
selective cameras build logic has been modified in libgphoto2-2.4.10 to build all
when CAMERAS is set to "*", nothing if empty and only the ones specified otherwise.

On Sun, 13 Feb 2011 18:03:41 +0100
Pacho Ramos <pacho@gentoo.org> wrote:
> Please see attached news item for reviewing as part of the fix for
> http://bugs.gentoo.org/show_bug.cgi?id=346491

CAMERAS=* shouldn't be legal. Since the strict IUSE stuff was dropped
from EAPI 4, and since IUSE isn't complete in any EAPI, there's no way
of implementing it correctly.

If you want to default to enabling a whole load of stuff, but allowing
users to override that, then you do it by listing things explicitly in
profiles.

--
Ciaran McCreesh

El dom, 13-02-2011 a las 17:09 +0000, Ciaran McCreesh escribió:
> On Sun, 13 Feb 2011 18:03:41 +0100
> Pacho Ramos <pacho@gentoo.org> wrote:
> > Please see attached news item for reviewing as part of the fix for
> > http://bugs.gentoo.org/show_bug.cgi?id=346491
>
> CAMERAS=* shouldn't be legal. Since the strict IUSE stuff was dropped
> from EAPI 4, and since IUSE isn't complete in any EAPI, there's no way
> of implementing it correctly.
>
> If you want to default to enabling a whole load of stuff, but allowing
> users to override that, then you do it by listing things explicitly in
> profiles.
>

Will CC the rest of the team for thinking about this then

On Sun, 2011-02-13 at 17:09 +0000, Ciaran McCreesh wrote:
> On Sun, 13 Feb 2011 18:03:41 +0100
> Pacho Ramos <pacho@gentoo.org> wrote:
> > Please see attached news item for reviewing as part of the fix for
> > http://bugs.gentoo.org/show_bug.cgi?id=346491
>
> CAMERAS=* shouldn't be legal. Since the strict IUSE stuff was dropped
> from EAPI 4, and since IUSE isn't complete in any EAPI, there's no way
> of implementing it correctly.
>
> If you want to default to enabling a whole load of stuff, but allowing
> users to override that, then you do it by listing things explicitly in
> profiles.
>

Wouldn't be any shorter way to build all CAMERAS? We don't want to
default to enabling all, with the new way of handling this, if CAMERAS
is not set or is empty, nothing will be built but, if CAMERAS="*"
shouldn't be used, what should we use instead of having to manually add
all of them to make.conf (from a user point of view)

Thanks

On Sun, 13 Feb 2011 20:31:23 +0100
Pacho Ramos <pacho@gentoo.org> wrote:
> Wouldn't be any shorter way to build all CAMERAS? We don't want to
> default to enabling all, with the new way of handling this, if CAMERAS
> is not set or is empty, nothing will be built but, if CAMERAS="*"
> shouldn't be used, what should we use instead of having to manually
> add all of them to make.conf (from a user point of view)

Why not specify all the CAMERAS you know about as being on by default in
the profile? Users who care enough can override this with an explicit
subset.

--
Ciaran McCreesh

On Sun, 2011-02-13 at 19:34 +0000, Ciaran McCreesh wrote:
> On Sun, 13 Feb 2011 20:31:23 +0100
> Pacho Ramos <pacho@gentoo.org> wrote:
> > Wouldn't be any shorter way to build all CAMERAS? We don't want to
> > default to enabling all, with the new way of handling this, if CAMERAS
> > is not set or is empty, nothing will be built but, if CAMERAS="*"
> > shouldn't be used, what should we use instead of having to manually
> > add all of them to make.conf (from a user point of view)
>
> Why not specify all the CAMERAS you know about as being on by default in
> the profile? Users who care enough can override this with an explicit
> subset.
>

If rest of gnome team agrees, I think we could go with, but I still fail
to see what is the "technical" problem on allowing CAMERAS="*" to be
used :-|

On Sun, Feb 13, 2011 at 1:34 PM, Ciaran McCreesh
<ciaran.mccreesh@googlemail.com> wrote:
> Why not specify all the CAMERAS you know about as being on by default in
> the profile? Users who care enough can override this with an explicit
> subset.
> --
> Ciaran McCreesh

This is how ALSA_CARDS and LCD_DEVICES are handled now. Its likely
that there are other examples too. It does provide for nice defaults
and easy user choice by override.

How many CAMERAs are we talking here, like 20 or 200?

--
Matthew W. Summers

On Sun, 2011-02-13 at 14:00 -0600, Matthew Summers wrote:
> On Sun, Feb 13, 2011 at 1:34 PM, Ciaran McCreesh
> <ciaran.mccreesh@googlemail.com> wrote:
> > Why not specify all the CAMERAS you know about as being on by default in
> > the profile? Users who care enough can override this with an explicit
> > subset.
> > --
> > Ciaran McCreesh
>
> This is how ALSA_CARDS and LCD_DEVICES are handled now. Its likely
> that there are other examples too. It does provide for nice defaults
> and easy user choice by override.
>
> How many CAMERAs are we talking here, like 20 or 200?
>

Around 60

On Sun, 13 Feb 2011 21:00:31 +0100
Pacho Ramos <pacho@gentoo.org> wrote:
> If rest of gnome team agrees, I think we could go with, but I still
> fail to see what is the "technical" problem on allowing CAMERAS="*"
> to be used :-|

'cameras_*' isn't a valid use flag name, so the package mangler can't
just pass the * through to the ebuild, which means it has to expand the
value itself. But there's no complete list of every CAMERA value
anywhere, so it can't.

There were plans to fix this in EAPI 4 by requiring that IUSE be
accurate. That would have allowed the package mangler to use IUSE to
get a complete list of known CAMERAS and be able to expand * that way.
Unfortunately, that feature got dropped, and so in EAPI 4 you're still
allowed to make use of USE_EXPAND variables without making sure IUSE is
complete.

--
Ciaran McCreesh

Ciaran McCreesh posted on Sun, 13 Feb 2011 20:17:09 +0000 as excerpted:

> On Sun, 13 Feb 2011 21:00:31 +0100
> Pacho Ramos <pacho@gentoo.org> wrote:
>> If rest of gnome team agrees, I think we could go with, but I still
>> fail to see what is the "technical" problem on allowing CAMERAS="*" to
>> be used :-|
>
> 'cameras_*' isn't a valid use flag name, so the package mangler can't
> just pass the * through to the ebuild, which means it has to expand the
> value itself. But there's no complete list of every CAMERA value
> anywhere, so it can't.

For sake of argument, what about the individuals, plus one called allknown,
or majorcams, or some such?

Meanwhile, most USE_EXPAND work by expanding to all if the flag is unset.
All or none, I believe it's worthwhile to keep USE_EXPAND behavior
consistent, so unless we're going to change all the others to build none
if they're unset, I'd say the package should build all possible if CAMERAS
isn't set.

--
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