[Aptitude-devel] Bug#570377: Fwd: Bug#570377: aptitude chooses to remove packages instead of upgrading

[Chris Tillman]

Thanks very much for your reply and explanation, Daniel. I can appreciate
that fiddling with defaults is a serious consideration. However, the
scoring system replaced the tiered system where removals were considered
less desirable than upgrades. So longtime users perceived a drastic change
in behaviour and in aptitude's "attitude".

I don't know why, with equal scores, aptitude now prefers the removals
option. Even with 3 to remove or 2 to upgrade, it still suggests the
removals first. By adjusting the default just one point, its behaviour was
completely different and it became a pleasure to use rather than seeming a
constant battle. There may not be a philosophical difference between
recommending removal of 3 packages including "gnome", vs. upgrading 2
packages including the one you asked to upgrade, but there is definitely a
psychological difference. So I'd argue that the 1-point advantage given to
upgrades would represent that psychological preference.

I really wonder about even the philosophical difference being 0. Users are
attempting to maintain their system. If a user asks for an install or
upgrade, surely more upgrades would be preferable. If they are doing
removals or downgrades, then perhaps removals would be the direction they
would want to go. Perhaps aptitude could be more sensitive to the requested
operation and adjust priorities accordingly. Would you be open to a patch
for that?

And, in any case, I certainly can't understand why the defaults chosen
should be carved in stone. 10000, 20000, 50000 ... these seem to have been
set nearly arbitrarily. Do we have any data about real-world user actions,
i.e. x choices presented in scored order and score[i] actually chosen, that
would allow us to zero in on truly representative weights which minimise i?

Thanks,
Chris




On Tue, Feb 4, 2014 at 6:29 AM, Daniel Hartwig <mandyke at gmail.com> wrote:

> On 2 February 2014 14:56, Chris Tillman <toff.tillman at gmail.com> wrote:
> >
> > Tags: patch
> >
> > I think the root of the problem (removing being preferential to upgrading
> > in Aptitude's worldview) is that the safe-level and remove-level default
> > scores are the same.
> >
>
> Hi
>
> Thanks for your interest and patch.  Unfortunately, it is not an
> acceptable solution to apply to the _default_ settings.
>
> There is nothing fundamentally better or worse about either removals
> or installs, in some situations you might find this:
>
>  solution 1: upgrade 20 packages
>  solution 2: remove 1
>
> Whichever is more preferable in these situations is up to the
> individual user to decide based on whatever particular packages are
> suggested for upgrade, install, or removal--aptitude can not know how
> the user values those individual actions.  The point of the safety
> cost _levels_ is to broadly class categories of actions, and in that
> sense, installing or upgrading to a package in the target release is
> no better or worse than removing a non-essential package.
>
> Tweaking the default settings as per the patch here is not to be done
> lightly.  Considering the architecture of the problem resolver as a
> whole, it is not an acceptable solution.
>
> I recommend any of Axels suggestions for individual users who are
> bothered by this, especially the comments about guiding the resolver
> by e.g. rejecting particular actions _before_ asking for the next
> solution.  This is also covered in the users manual, _Resolving
> Dependencies Interactively_.  That is the most effective way of
> informing the resolver about your desires.
>
> Regards
>



-- 
Chris Tillman
Developer



-- 
Chris Tillman
Developer
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