Re: Detecting dependency cycles and conflict dependency problems in packages
On Sat, 22 Dec 2001 01:38:44 +0100
"Nicolas Chauvat" <chauvat@nerim.net> wrote:
> Anyhow, my pet project for tonight was to write such a graph checker.
I (and others i know of) have thought about this problem, it is an
intersting problem, i dont think anybody has come up with a good
solution yet.
Most cycles arent bad, some package depend on themselves (their virtual
package).
> What I call a dependency cycle is something like (A depends on B and B
> depends on A) which basically implies that A and B *have*to* be
> installed and removed together. It may not be a mistake for some
closely
> related packages, but chances are that it will be with cycles of
lenght
> longer than 2.
>
These types of cycles arent a problem, as you say they can be installed
together.
A bad cycle which would make a package uninstallable would be if A
Pre-Depends on B and B Depends or Pr-Depends on A (and visa versa)
> What I call a conflict dependency problem is something like (A
conflicts
> with B and B depends on A). I saw at least one case where this was on
> purpose to facilitate upgrade, but I would say that it is an actual
> problem in most cases.
>
Some of these will be false alarms as you have to take into account
virtual packages (Provides: field).
e.g.
gaim **> gaim-gnome --> gaim-common --> gaim
gaim-gnome provides the virtual package gaim which satisfies gaim-common
Best of luck
Glenn
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