On Tue, 24 Oct 2006, Frank Küster wrote: > Don Armstrong <[EMAIL PROTECTED]> wrote: > > On Tue, 24 Oct 2006, Petter Reinholdtsen wrote: > >> [Ian Jackson] > >> > The only argument I've heard against circular dependencies as a > >> > general rule is that they can trigger a particularly stupid (and > >> > probably not very hard to fix) bug in apt, > >> > >> You seem to have missed the argument that packages with circular > >> dependencies are impossible to install and configure in the correct > >> (dependency) order, and thus will end up being installed and > >> configured in a nondeterministic order instead. It is documented > >> that dpkg try its best to find a sensible order for the packages, > >> but it is bound to fail one way or another if two packages really do > >> need each other to be configured before they are configured. > > > > Packages which have circular dependencies and depend on the other > > package being configured are buggy; at most they can depend on the > > other package being unpacked. Since there is no way to specify this > > kind of dependency, Depends: is as close as you can get. > > It seems to me that the solution in such situation shouldn't be a > circular dependency with its "nondeterministic" behavior,
The end behavoir is only nondeterministic if the packages in the set care what order they are configured in. If they do, that's a bug. > but instead to separate one of the packages into two. For example if > package b needs package a unpacked, but not configured, separate > package a in a-data and a-therest, where a-data provides all that > package b needs: Now b can depend on a-data, and a-therest can > depend on b. This is inherently fragile and requires a and b to be closely cooperating packages; it also makes it difficult to define an 'a-therest' requires 'a-data' >> someversion dependency. (You'd have to release a new version of b to do so.) I'm all for removing unecessary circular dependencies, but hacking around necessary circular dependencies is ugly. Far better to fix the tools if they're unable to handle them properly. Don Armstrong -- Taxes are not levied for the benefit of the taxed. -- Robert Heinlein _Time Enough For Love_ p250 http://www.donarmstrong.com http://rzlab.ucr.edu
