http://bugzilla.wpkg.org/show_bug.cgi?id=117 --- Comment #9 from Frank Lee <rl201 at cam.ac.uk> 2008-05-09 18:47:33 --- > I clearly have to state here that a dependency clearly means to me that a > package really does not work at all if the package it depends upon is not > installed. Aha, this is where the problem is then: we understand different things by the same term. > For example I use dependencies on a package called "shortcut" which itself has > very low priority as it is not a user program important to be on the system for > users. However the applications which depend on it will fail to install (or at > least to create the shortcuts) if this program is not installed. So for me this > is a dependency. I would also call this a dependency. But I would say a tool which is used to install programs ought to have a higher priority than the programs which use it! > Each time an application which depends on "shortcut" is installed it makes sure > "shortcut" is actually installed properly (before). So WPKG might end up doing lots of checks it didn't need to do? (Not a huge problem I guess...) > If it wouldn't do that then I could also simply omit the dependency. However I > would have to add both packages to the profile then. > In my eyes you're not talking about real dependencies. You're talking about > includes! So you say that if a package is installed another one is > automatically pulled to the profile (regarding its priority). Okay, I'm happy to call them "includes". > There is anyway an ongoing discussion for "chained installations" (see Bug > 111). > To me it looks like your goal would simply be to "pull" some packages to the > profile which are not actually add to the profile. Each package should be able > to pull some other packages while the install order completely depends on the > package priorities. > To allow this I would clearly add a new XML node like <include... />. I'm happy to do that (again) - but perhaps I should be much clearer about what I intend it for this time! > I am absolutely against re-defining the meaning of dependencies as I totally > disagree that dependencies should be related in any way to priorities. So was I, but the meaning of dependencies has already changed from the original meaning. > In general I don't like priorities at all (almost all my packages have priority > 50). Why? It's quite simple - if one uses a proper dependency management it > would even be possible to install all packages in parallel. But this only works > if you know all the dependencies between them because some of them have to wait > until others are finished (no matter what their priority is). I'm not so sure - none of my packages depend (in my meaning or yours!) on the virus scanner. But I want the virus scanner to be installed first, so it has a high priority. > Hava a look at Unix init scripts. Older systems are based on priorities which > are controlled by the file name. This does not allow to start multiple scripts > in paralle. All newer systems (look at Gentoo or BSD) define dependencies > between modules and allow to run them independently. This works perfectly if > dependencies are inserted properly. OK, I have to admit that parallel package > installation is not so easy (Windows installer does not work in parallel) but > you get the idea. I get the idea - it's a nice analogy. > Bug 111 goes into a slightly different directory. It asks for chained > installation. Therefore the algorithm using dependencies, includes and chained > installations would be as follows (simplified): > > - add included packages of all applying packages to the profile > - sort packages > - start installation > - check for dependencies, install them if required > - install actual package > - run chained packages in order > > Again, cheined packages will not regard priorities as a package with very high > priority will also install a chained package even with lowest priority before > proceeding to the next package. I could find a use for what I think of as 'depends for installation', I'm sure! > Again, dependencies are called dependencies since the package specifying the > dependency really needs the specified package to run or even to install. So I > will not change that as it will potentially break a lot of systems. They're not! They're called dependencies because the debian package management system uses the same syntax and at the time I wanted what the debian package management provided. In fact, the first implementation of it even had a comma-separated list of packageIDs, rather than XML entities, just as the debian syntax! The debian equivalent of what they have become is 'Pre-Depends'. (The terminology is unhelpful: I don't suggest we adopt it!) Yours, Frank -- Configure bugmail: http://bugzilla.wpkg.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the QA contact for the bug. |