[Buildroot] lua interpreter choice?

[Yann E. MORIN]

Danomi, All,

On 2014-07-30 18:34 -0400, Danomi Manchego spake thusly:
> On Wed, Jul 30, 2014 at 5:40 PM, Thomas Petazzoni
> <thomas.petazzoni at free-electrons.com> wrote:
> > Dear Danomi Manchego,
> >
> > On Wed, 30 Jul 2014 14:51:49 -0400, Danomi Manchego wrote:
> >
> >> > this change in the virtual-package behavior was introduced by
> >> > http://git.buildroot.net/buildroot/commit/?id=91169d3346e543be18139e18bdcc52a2345e0d16
> >> > (infra/pkg-virtual: validate only one provider provides an implementation)
> >> >
> >> > François
> >>
> >> But the menuconfig still lets you select both packages, instead of
> >> providing a choice of one or the other (like "jpeg support").  Is this
> >> not undesirable?
> >
> > We discussed this before doing the commit pointed by François.
> > Unfortunately, there's no good solution to solve this problem at the
> > kconfig level. The only solution would be to have each package being a
> > provider of a certain virtual package, have the knowledge of *all*
> > providers of that virtual packages to do a "depends
> > on !BR2_PACKAGE_<foo>". While for lua vs. luajit this seems more or
> > less reasonable, as we probably don't expect to have more providers
> > than just lua and luajit, but in the general case, we have things like
> > libgles or egl (for OpenGL support) which have multiple providers, and
> > we don't want to have to edit all of them whenever we add a new
> > provider.
> >
> > Not speaking about packages in BR2_EXTERNAL, which we cannot control.
> >
> > So our decision was to use a build-time check rather than a
> > kconfig-time check.
> >
> > Hope this clarifies the situation,
> 
> Let me apologize in advance if I'm still missing something obvious but
> - what distinguishes the lua/luajit case from the libjpeg/jpeg-turbo
> case, or the systemd/eudev case?  Is the virtual-package
> infrastructure + kconfig choice not suitable here?

It just occured to me that I only replied to half your questions.

As for libjpeg/jpeg-turbo: the choice was pre-existing before the
virtual package infra was added. It was decide to keep them as-is,
rather than to fully convert them.

As for eudev vs. systemd: they are not really a choice og one _or_ tghe
other, since you can still have none. Besides, they are not the same
thing: systemd is an init system, daemon; eudev is a /dev management
system. So we do really need choices here, because what we're selecting
is not a provider of a virtual package, but an init system or a /dev
management system. It happens that both are also providers of udev.

Hopefully this further clarifies the situation.

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'