Gentoo Linux developer list

Kent Fredric | 29 Jun 2012 03:41

Feature Request/RFC : "Elective" virtuals

I was doing a fresh Gentoo install today, following the manual, and it
appeared to me that the manual suggests to install a "logger" and a
"cron", and gives some defacto suggestions.

However, the available packages that provide this facility(s) are not
overly obvious from a portage standpoint.

The best index I can find presently for a list of things that provide
these facilities are virtual/cron , and virtual/logger , and only then
by perusing the source.

And if you tell somebody to install "virtual/cron", you'll get the
first thing in the ||( ) list, not an elective choice of which to
install.

It makes sense to me that there are some circumstances, where it makes
sense to, instead of simply picking the first match, present the user
with the option of one of them ( somehow ).

ie:   emerge -pv virtual/cron  could, instead of the current behaviour
of installing vixie-cron,show a list with the non-chosen alternatives:

What we presently get is this:

[ebuild  N     ] sys-process/vixie-cron-4.1-r12  USE="pam -debug
(-selinux)" 0 kB
[ebuild  N     ]  virtual/cron-0  0 kB

Where it might be nice to instead give:

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Ian Stakenvicius | 29 Jun 2012 14:30

Re: Feature Request/RFC : "Elective" virtuals


On 28/06/12 09:41 PM, Kent Fredric wrote:
> I was doing a fresh Gentoo install today, following the manual, and
> it appeared to me that the manual suggests to install a "logger"
> and a "cron", and gives some defacto suggestions.
> 
> However, the available packages that provide this facility(s) are
> not overly obvious from a portage standpoint.
> 
> The best index I can find presently for a list of things that
> provide these facilities are virtual/cron , and virtual/logger ,
> and only then by perusing the source.
> 
> And if you tell somebody to install "virtual/cron", you'll get the 
> first thing in the ||( ) list, not an elective choice of which to 
> install.
> 
> It makes sense to me that there are some circumstances, where it
> makes sense to, instead of simply picking the first match, present
> the user with the option of one of them ( somehow ).
> 
> ie:   emerge -pv virtual/cron  could, instead of the current
> behaviour of installing vixie-cron,show a list with the non-chosen
> alternatives:
> 
> What we presently get is this:
> 
> [ebuild  N     ] sys-process/vixie-cron-4.1-r12  USE="pam -debug 
> (-selinux)" 0 kB [ebuild  N     ]  virtual/cron-0  0 kB
>

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Kent Fredric | 29 Jun 2012 19:33

Re: Feature Request/RFC : "Elective" virtuals

>
> Perhaps it would be best to tell users that if they'd like to see the
> possible choices they can run ie 'qdepends -r virtual/cron'
>

Quite, perhaps it could be a seperate mechanism, it would just seem
that for virtuals that just provide a list of alternatives, having a
seperate package that gives the *choice* of one of those alternatives
seems like redundant code. ( Most virtuals are simple non-exclusive
ors, so the packages that satisfy them can all be installed
simultaneously,  however, there are a few virtuals that are inherently
exclusive-ors, as all the dependents exclude each other )

Perhaps it could be an additional metafield, upon which the choice of
one of several choices could be presented to the user by using a
different tool.

All packages which have an "alternatives" mechanism like this could
then also be indexed and the user could then only enter the selection
process with a  separate tool which is a wrapper for portage.

I'm not sure if it makes sense or not to make it as an eselect
submodule that lets the user make choices and then have something else
apply them, or a dedicated tool; ie:

eselect alternatives list  # list all the "things" that have
dependents that are mutually exclusive choices
eselect alternatives set cron --auto # selects vixie-cron
eselect alternatives set cron cronie
emerge -uvatDN  <at> changed_alternatives

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