Hello. After working with mixed stable/testing/unstable systems for several years, it seems for me that I know what apt-get needs to support more or less painless administration of such systems.
1. Currently, it seems that apt's problem-solver consideres exactly one candidate for each package. On a mixed system, too often the following happens: - package A is installed from one branch (e.g. unstable), - package B is installed from another branch (e.g. testing), - A is being upgraded, - newer A versioned-depends on B, and version of B in testing can't satisfy this dependency. Currently this causes apt to report an error. So manual "B/unstable" is needed in the command line. It's not a problem (just somewhat annoying) if the dependency chain is one-package-long, but when playing with large packages like KDE it takes too long time to manually find ann individual packages that need to be "switched to other branch". Using "-t unstable" (or other way to change branch priorities) is not convenient, because this will "switch to unstable" also packages for which such switch is not required. This breaks the "upgrade only if what is needed to upgrade" policy that I try to follow. A good solution will be if apt (when a command-line switch is given), if failes to find an upgrade path, will try different versions of packages. Seems that dependency information may give hints on which packages to try non-default versions, so complete enumeration of possibilities will not be needed. 2. When doing massive operation (dist-upgrade), sometimes apt's solution is not perfect. It will be good if apt will accept some hints from the command line (e.g. which pakcages to add, and which to remove). 3. When there are several binary packages built from the same source package, and one of binary packages is being upgraded, if will be good if apt (with some additional command-line switch) also upgrades the other installed binary packages from the same source package. This will help to avoid unwanted situations like documentation (or support binaries) for a version of library that differs from installed one. Such cases can't be handled by dependences: documentation should not depend on the library because one cat want to install it without installing the loibrary; documentation should not conflict with other versions of the library because this will beat people on slow links who prefer to accept a mismatch. I am thinking about trying to implement the above. Is there any documentation on apt internals available?
