On 10/20/2014 at 11:59 AM, David Kalnischkies wrote: > On Sun, Oct 19, 2014 at 09:32:54AM +0200, Matthias Urlichs wrote: > >> David Kalnischkies:
>>> This isn't trying harder, it is trying increasingly incorrect >>> solutions to the problem because aptitude assumes the users is >>> not able to express himself correctly. apt-get is treating its >>> user as its god instead, aka: user is always right, even if it >>> makes no sense in apt's simple mind. >>> >> My main problem is that, whenever I install a "difficult" package, >> the first solution I get presented is always to simply not install >> the package in question. The next 2^n-1 "solutions" transitively >> remove everything that currently conflicts with installing the >> thing in question. Rejecting the removal of a few core packages >> then gets me the correct solution, e.g. upgrading two packages. > > I think aptitude is calling this canceling actions. I would bet you > can use this config setting to discourage it from doing that, but > ultimately its a design choice to allow or forbid them at all. > >>> Selecting one package in an or-group is a grand example of people >>> not understand their tools although the policy is simple and >>> logic: If it isn't impossible to let it win, the first >>> alternative wins. If the package manager would go for any >>> heuristic based on simplicity of installation instead everyone >>> would have lsb-invalid-mta as MTA because that is damn easy to >>> install by any standard. Maintainers are very heavily relying on >>> this property while e.g. building packages. >> >> You don't have to drop that part of its logic. Choosing a different >> package as a dependency should of course be a "last resort" action >> (i.e. be heavily penalized). I'm not talking about changing that. >> I'm talking about the fact that aptitude treats upgrading to a >> slightly-lower-prioritized version of a package as a *way* worse >> solution than removing that package (and/or 500 others). > > Well, "slightly lower" priority means packages from a different > release in general, so that isn't a safe action either. experimental > and backports come to mind. Never upgrading to a security fix is > another. > > Also – but that might be a relatively controversial point – users > are much better at figuring out which packages they don't want > removed compared to e.g. which packages should be held at a lower > version, so I can optimize the other values and let the user decide > along a property he can easily reason about (I am not suggestion that > aptitude or apt-get work that way, but who knows that for sure > anyway, right?). What I think is being asked for (and what I'd certainly like to see, anyway) is a way for the user, having figured out which packages they don't want removed, to tell the aptitude resolver that and have it taken into account in calculating a dependency solution. As it happens, there's an obvious way to do that: specify the package(s) you don't want removed on the aptitude command line. However, one of the behaviors I've observed - which I think, per the quote above, is part of exactly what is being complained about - is that aptitude will often propose a solution which involves "keep package-X-from-command-line at its current version" before proposing a solution which involves "install a new version of that same package". Thus, specifying a package on the command line does not effectively tell the aptitude resolver that you don't want it removed. (I'm pretty sure I've seen a proposed solution, in a package-upgrade scenario, which involved "remove package X and everything that depends on it", as well. But I don't recall any specifics on that one, so it might be my imagination.) My core objection to aptitude is less that it proposes non-optimal solutions first (although that's certainly part of it) than that it frequently, indeed perhaps consistently, proposes solutions which involve *not doing the actual thing which was requested* before proposing ones which do. That does not seem remotely reasonable, to me. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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