Should we allow packages to depend on packages with lower priority values?

[Marc Haber <mh+debian-policy@zugschlus.de>]

Policy 2.5 says that packages must not depend on packages with lower
priority values. From what I tried to research, that rule is meant to
allow CD builders to build "Debian foo standard" CDs containing
required, important and standard packages, guaranteed that all
dependencies are satisfied just from choosing from the Priority.

This must be residue from the times when CD building tools didn't
follow dependency chains. Today, it is trivial to build
dependency-complete "Debian standard" CDs by including required,
important and standard packages and following down the dependency
chain. apt-get is a tool that can solve this, and at least the old CD
building tools used apt-get to resolve the dependencies. This has been
the case at least since slink when I joined the Debian user community.

This being said, I'd like to point out a problem that this policy
requirement poses.

Let A and B both be packages that provide virtual package C. A is the
default C in Debian, and is therefore Priority: important. A depends
on E and F, which must be Priority: important as well, as required by
current Policy.

Now let's look at a system where the local administrator has decided
to use B instead of A. Since E and F are Priority: important, dselect
happily proceeds to install E and F on the system, even if they are
not needed since the system in question uses B instead of A.

To put it short: The last paragraph of Policy 2.5 is cruft that is no
longer needed any more. It should be removed from Policy since we have
had CD builder packages available that can follow dependency chains.

I don't see other reasons behind the requirement, but am of course
open to arguments. Did I overlook something?

Greetings
Marc

-- 
-------------------------------------- !! No courtesy copies, please !! -----
Marc Haber          |   " Questions are the         | Mailadresse im Header
Karlsruhe, Germany  |     Beginning of Wisdom "     | Fon: *49 721 966 32 15
Nordisch by Nature  | Lt. Worf, TNG "Rightful Heir" | Fax: *49 721 966 31 29